Quantum Symposium
International Symposium on
“Single Photon based Quantum Technologies”
May 30June 1, 2018 in Berlin, Germany
Join our symposium by giving a talk, presenting a poster, or without any presentation. We especially encourage young scientists to present their work with an oral presentation. A special prize will be awarded for the “Best Student Talk”.
Aim and purpose
About a century ago, the theory of quantum mechanics was born. By virtue of its extraordinary explanatory power this theory has not only dramatically changed to the way we see the world, but also led to a first quantum revolution that has brought us groundbreaking new technologies such as the transistor, solidstate lighting, lasers, and GPS.
Today, we are paving the way for a second revolution. With quantum theory now fully established, we are beginning to look at the world in a fundamentally new way: objects can be in different states at the same time ("superposition") and can be deeply connected without any direct physical interaction ("entanglement"). By way of breathtaking advances in creating and manipulating dedicated entangled and/or superimposed quantum states, new technologies will emerge that promise to change our society in the next 520 years through revolutionary methods in imaging, sensing, communication, simulation and computation. However, in many of the related research fields, we are still at the beginning of transferring theory into technology.
The purpose of this symposium is therefore to provide an interdisciplinary platform for the exchange of experience and information as well as sharing recent findings in the field of single photon based quantum technologies. The symposium will cover a rather broad range of topics, since “single photons” are one important basis for many quantum technologies, such as singlephoton detectors and sources, metrology and sensing, correlations and entanglement, communication and QKD, information processing, or integrated photonic quantum circuits.
Student award
As nurturing young scientists is important to PicoQuant, we host a competition for the “Best Student Talk” with an award worth 750 Euro. Undergraduate and graduate students are encouraged to participate in this best presentation competition.
The submission of abstracts for oral presentations is now closed. The winner of the "Best Student Talk" will be announced on June 1.
Undergraduate and graduate students are invited to submit their contributions until May 31, 2017. Please indicate during the registration/abstract submission if you wish to participate in the contest.
Important dates
 The registration is already open
 Deadline for submission of abstracts: February 5, 2018
 Deadline for early bird registration: February 5, 2018
 Final deadline for symposium registration: April 30, 2018
 Notification on acceptance of abstracts: early March 2018
 Program available: mid/end March 2018
 Deadline for submission of abstracts for postdeadline posters: August 15, 2017
Contact
Symposium coordinator: Kerstin Wicht
Tel: +4930120882087
Fax: +4930120882090
Email: events@picoquant.com
Please note: schedule and content of this event is subject to change without notice.
Invited speakers and their titles
 Ivo P.Degiovanni
INRIM, Italy
"Quantum metrology vs. quantum enhanced measurements (with photons)"  Mark Fox
University of Sheffield, UK
"Onchip quantum photonics with integrated quantumdot singlephoton sources"  David Gershoni
Technion Israel Institute of Technology, Israel
"Deterministic generation of a cluster state of entangled photons, using semiconductor quantum dots"  Ronald Hanson
TU Delft, The Netherlands
„Quantum networks“  Wolfram Pernice
University Münster, Germany
"Waveguide integrated single photon detectors"  Jürgen Mlynek
Former president of the Helmholtz Foundation, Germany
"The second quantum revolution  The EU flagship on quantum technologies"
 Andrew Shields
Toshiba Research Europe Ltd., UK
"Quantum communications based on semiconductor devices"  Christine Silberhorn
University Paderborn, Germany
"Integrated quantum optics"  Varun Verma
NIST, USA
"Progress in single photon imaging from the UV to the mid infrared using superconducting nanowire detectors"  Ian Walmsley
University of Oxford, UK
"Photonic quantum networks: a ubiquitous platform for quantum technologies"  Ronald Walsworth
Harvard University, USA
"Nanoscale magnetic imaging using quantum defects in diamond"
Program committee
Symposium Topics
Since “single photons” are one important basis for many quantum technologies, the symposium will cover a rather broad range of topics, such as:
 Singlephoton detectors
 Singlephoton sources
 Quantum metrology
 Quantum correlations and entanglement
 Quantum information processing
 Quantum communication and QKD
 Quantum sensing
 Integrated photonic quantum circuits
 ...
Abstract submission
Abstract submission for both oral and poster presentations is now closed.
The deadline for abstract submission is May 31, 2017. Post deadline abstracts may not be considered.
Abstract submission is open. The deadline for abstract submission is February 5, 2018. Post deadline abstracts may not be considered.
 Abstracts can be submitted for oral or poster presentation. Depending on the number of received abstracts, some oral presentations may be changed to a poster presentation.
 Abstracts can only be submitted along with the registration for the workshop.
 Abstracts must be submitted in English containing not more than 200 words (body text) and no graphics.
Abstract submission for oral presentations is closed. Abstracts for post deadline poster presentations can still be submitted.
 Abstracts can only be submitted along with the registration for the workshop.
 Abstracts must be submitted in English containing not more than 200 words and no graphics.
 Notification on acceptance of abstracts: early March 2018
 Program available: mid/end March 2018
Program (as of May 25)
08:00  09:00  Registration and collection of symposium material 
09:00  09:15  Andreas Bülter, Berlin, Germany Opening Remarks 
09:15  09:45  Jürgen Mlynek, Berlin, Germany (Opening Talk, Invited Speaker) The second quantum revolution  The EU flagship on quantum technologies 
Session: Quantum Information ProcessingChair: Jürgen Mlynek  
09:45  10:15  Photonic quantum networks: a ubiquitous platform for quantum technologies Ian Walmsley Oxford University Light has the remarkable capacity to exhibit quantum features under ambient conditions, making exploration of the quantum world feasible in the laboratory and in the field. Further, the availability of highquality integrated optical components makes it possible to conceive of largescale photonics quantum states by bringing together the outputs of many different quantum light sources, coherently mixing them and counting the output photon number. We can envisage a scalable photonic quantum network that will facilitate the preparation of distributed quantum correlations among many light beams, thereby enabling a new regime of state complexity to be accessed  one for which it is impossible using classical computers to determine the structure and dynamics of the system. This is a new regime not only for scientific discovery, but also fro applications: it is possible to perform tasks that are impossible using known future information processing technologies. For instance, ideal universal quantum computers may be exponentially more efficiently than classical machines for certain classes of problems, and communications may be completely secure. Photonic quantum technologies will open new frontiers in quantum science and technology. 
10:15  10:35  Spectral manipulation of quantum light by complex temporal phase modulation Filip Sośnicki, Maciej Gałka, Michał Mikołajczyk, Ali Golestani, Michał Karpiński Faculty of Physics, University of Warsaw, Pasteura 5, 02093 Warszawa, Poland The spectraltemporal degree of freedom of light is a promising platform for integrated photonic quantum information processing. The intrinsically deterministic electrooptic methods, allowing imprinting temporal phase profiles onto optical pulses in a noisefree manner, show great promise for spectral manipulation of quantum pulses. To date, using singletone electrooptic phase modulation we demonstrated 6fold spectral compression of heralded single photon pulses [1], as well as deterministic spectral shifting of singlephoton wavepackets [2]. Here we discuss spectral manipulation of light by more complex temporal phase modulation patterns. We show that the use of phase modulation patterns akin to spatial holograms for diffractive shaping of transverse beam profiles may enable truly largescale bandwidth compression. Our numerical simulations indicate the feasibility of reaching compression factors of the order of 103, enabling interfacing GHz and MHzbandwidth quantum systems. Further we experimentally demonstrate an ondemand, nonperiodic electrooptic temporal phase modulation system, based on direct driving of electrooptic phase modulators with output signals from photodiode receivers. The nonperiodicity of the scheme is particularily relevant for nondeterministic events prevalent in photonic quantum information processing. Our results demonstrate the added value for spectral manipulation of quantum light stemming from nonsinusoidal electrooptic temporal phase modulation patterns. [1] M. Karpiński, M. Jachura, L. J. Wright, B. J. Smith, Nature Photon. 11, 53 (2017). [2] L. J. Wright, M. Karpiński, C. Söller, B. J. Smith, Phys. Rev. Lett. 118, 023601 (2017). 
10:35  10:55  Single and twophoton switching in 1D waveguides with Fano interference Kristoffer Joanesarson^{1}, Jake IlesSmith^{1,2}, Mikkel Heuck^{1}, Yi Yu^{1}, Jesper Mørk^{1} ^{1}Department of Photonics Engineering, Technical University of Denmark, Ørsteds Plads, 2800 Kgs. Lyngby, Denmark Single photon switches have potential for future applications within optical quantum information processing and communication [1]. A potential realisation of a scalable onchip singlephoton switch is a single quantum scatterer with discrete energy levels inside a onedimensional photonic crystal waveguide [2]. Incident photons onresonance with the scatterer will completely reflect, whereas faroff resonant photons will transmit. [1] D. E. Chang, V. Vuletić, and M. D. Lukin, Nature Photonics, 8, 685 (2014). 
10:55  11:30  COFFEE BREAK 
Session: Single Photon Detection & ManipulationChair: Ian Walmsley  
11:30  12:00  Waveguide integrated single photon detectors Wolfram Pernice University of Münster, Institute of Physics, Münster, Germany Nanophotonic circuits employ waveguiding devices to route light across quasiplanar integrated optical chips in analogy to electrical wires in integrated electrical circuits. Using materials with high refractive index allows for confining light into subwavelength optical wires. Interaction with the environment is possible through nearfield coupling to the evanescent tail of propagating optical modes. This approach is particularly interesting for designing highly sensitive detectors which are able to register individual photons and constitute fundamental building blocks for emerging quantum photonics. I will present recent progress on realizing waveguide integrated single photon detectors, with a focus on superconducting nanowire single photon counters (SNSPDs). SNSPDs provide high efficiency and good timing performance, as well as broad optical detection bandwidth. To move towards applications in high bandwidth quantum communication, ultrafast detectors with high efficiency are needed. We realize compact SNSPDs with submicrometer effective length by embedding them in photonic crystal cavities to recover high absorption efficiency. These detectors possess subnanosecond recovery times and ultralow noise equivalent power. Being made by scalable fabrication techniques, waveguide SNSPDs hold promise for photonic integrated quantum technologies. 
12:00  12:20  Highfidelity photonnumberresolving detector and photonstatistics measurement Josef Hloušek, Ivo Straka, Michal Dudka, Martina Miková, Miroslav Ježek Department of Optics, Palacký University, 17. listopadu 1192/12, 77146 Olomouc, Czech Republic Accurate characterization of statistics of light is a crucial requirement of many applications in the field of quantum technology such as nonclassical light preparation and characterization, quantum sensing and metrology, and quantum simulation. Photonnumberresolving measurements also represent enabling technology for many emerging biomedical imaging techniques. We present a photonnumberresolving detector consisting of a tunable freespace optical multiport network and a number of independent singlephoton avalanche diodes. The spatial multiplexing scheme features precise balancing with no crosstalk between the individual detection ports and other systematic errors. Subsequent data processing is based on a realtime measurement of all the possible coincidence events between the ports. To estimate photon statistics of the input light, we apply a novel expectationmaximizationentropy algorithm based on entropy regularization of maximumlikelihood approach and expectationmaximization iteration technique [1]. We demonstrate highfidelity photon statistics measurement of various sources of light, including laser, single and fewmode thermal sources, photonsubtracted thermal light, and a set of several singlephoton emitters [2]. The accurate photonstatistics measurement is also utilized for experimental verification of quantumthermodynamics concepts [3]. [1] J. Hloušek and M. Ježek, in preparation. [2] I. Straka, L. Lachman, J. Hloušek, M. Miková, M. Mičuda, M. Ježek, and R. Filip, npj Quant. Inf. 4, 4 (2018). [3] J. Hloušek, M. Ježek, and R. Filip, Sci. Rep. 7, 13046, (2017). 
12:20  12:40  Towards HighTc Superconducting Nanowire Single Photon Detectors Martin A. Wolff^{1,2}, Matvey Lyatti^{1}, Simone Ferrari^{1,2}, Wolfram H. P. Pernice^{1,2}, Carsten Schuck^{1,2} ^{1}University of Münster, Physics Institute, WilhelmKlemmStr. 10, 48149 Münster, Germany The idea of exploiting the optical response of superconductors in bolometers, transition edge sensors and singlephoton detectors is an active and rapidly growing field of research. In particular integrated quantum technology will benefit from embedding superconducting nanowire singlephoton detectors (SNSPDs) with nanophotonic circuits. The vast majority of superconducting detectors however is rather demanding in terms of cryogenic environments requiring temperatures below 4 K. Hence, there is a growing interest in exploring the potential of highcritical temperature (highTc) superconductors for singlephoton detection, which could allow for operation under significantly relaxed (liquid nitrogen) cooling requirements. Such highTc SNSPDs will further benefit from faster intrinsic electronphonon interaction times thus resulting in detectors operating at higher speeds. Here we show progress towards the realization of highTcSNSPDs fabricated from ultrathin yttrium barium copper oxide (YBCO) films. We employ focused ion beam milling for the fabrication of highquality YBCO nanowires on strontium titanate (STO) substrates, which is well suited as a waveguiding material. First optical experiments at liquid nitrogen temperatures show a bolometric response and reveal complex vortex dynamics at 4 K, resulting in voltage switching, which is the basis for singlephoton detection. In future work we will integrate YBCO nanowires with STO waveguides for integrated onchip photodetection applications. 
12:40  13:00  Optical Tweezers for Neutral Atoms: The Key to a Reliable AtomPhoton Quantum Interface Naomi Holland, Dustin Stuart, Klara Theophilo, Axel Kuhn University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK A deterministic and coherent interface between atomic excitations and photonic states is a fundamental building block for hybrid quantum computation in a scalable quantum network. We aim to implement a novel singleatom singlephoton interface via a highfinesse optical cavity [1]. To make the process deterministic, the atoms are trapped in microscopic dipole traps (optical tweezers), which may be dynamically reconfigured using a spatial light modulator (SLM) [2]. The optical tweezers are holographically generated  we discuss the physical setup used to realise this, along with a number of algorithms that may be used to calculate the holograms required to be displayed on the SLM [3]. We present our results in trapping arrays of single atoms in arbitrary configurations, and our current work towards moving these trapped single atoms to arbitrary locations. Finally, we discuss the possible integration of these techniques with the fibretip cavities also under construction in our group, and the significance of this to the field of quantum computation. [1] A. Kuhn, Cavity Induced Interfacing of Atoms and Light. Ch.1 in: Engineering the AtomPhoton Interaction. Springer (2015). [2] D. Stuart and A. Kuhn, New Journal of Physics, 20, 023013 (2018). [3] N. Holland et al., preprint, arXiv:1711.07845 (2017). 
13:00  14:30  LUNCH BREAK 
Session: Quantum MetrologyChair: Wolfram Pernice  
14:30  15:00  Quantum Metrology vs. Quantum Enhanced Measurements (with Photons) Ivo Degiovanni I.N.RI.M. Istituto Nazionale di Ricerca Metrologica, Torino, Italy For quantum physicist Quantum Metrology means highresolution and highly sensitive measurements of physical parameters strictly exploiting “purequantum” features, such as e.g. quantum entanglement and/or quantum squeezing. For metrologists Quantum Metrology represents the novel field of metrology developing measurement techniques necessary for the market success of quantum technologies. These measurement techniques are not limited to measurements of enhanced precision by exploitation of “pure quantum” features. Quantum metrology also contributes to the revised International System of Units (SI) based also on specific quantum effects allowing the “miseenpratique” of units directly from the fundamental constants. This talk will discuss """quantum metrology""" from the perspective of metrologists, and from the one of quantum physicists, presenting some paradigmatic example of the two approaches based on photons. 
15:00  15:20  Quantum enhanced absorption measurement with twin beams Elena Losero^{1,2}, Alice Meda^{1}, Ivano RuoBerchera^{1}, Alessio Avella^{1}, Marco Genovese^{1,3} ^{1}INRIM, Strada delle Cacce 91, I10135 Torino, Italy The use of quantum states of light can lead to significant improvements in absorption measurements respect to the limits imposed by their classical counterpart. Indeed, classical measurements are unavoidably limited by the intrinsic photon number fluctuations (i.e. shot noise) which scale as 1/ sqrt(n) and which can become the main source of uncertainty when low level of light is used. After a brief introduction to quantum imaging and to the advantages of exploiting photon number correlation in spatially multimode twin beams (see Ref .[1,2]), we present recent results on the estimation of transmission/absorption coefficient with true and significant quantum enhancement. We investigate different estimators in terms of sensitivity, discussing on one side their relation with the best known strategy (i.e. using Fock states probe , see Ref. [3,4,5]), but also practical issues related to their implementation (e.g. the requirement on the stability of the system). It turns out that for very small absorption some of them are better suited to provide an unbiased and absolute estimation in an experimental measurement. We demonstrate that in ideal conditions twin beams can reach the ultimate sensitivity for all energy regimes, moreover, we propose a model to take into account for experimental imperfections and we perform the experiment reporting the best sensitivity per photon ever achieved in loss estimation experiments. [1] A. Meda, E. Losero, N. Samantaray, S. Pradyumna, A. Avella, I. RuoBerchera, M. Genovese, Journal of Optics 19, 094002 (2017) [2] G. Brida, M. Genovese & I. Ruo Berchera, Nature Photonics 4, 227 (2010); G. Brida, M. Genovese, A. Meda, & I. Ruo Berchera, Phys. Rev. A 83, 033811 (2011). [3]G. Adesso, F. Dell’Anno, S. De Siena, F. Illuminati, and L. A. M. Souza, Phys. Rev. A 79, 040305(R) (2009) [4]Alex Monras and Matteo G. A. Paris, Phys. Rev. L 98, 160401 (2007) [5]R. Whittaker, C. Erven, A. Neville, M. Berry, J. L. O’Brien, H. Cable and J.C.F. Matthews, New J. Phys. 19 023013, (2017) 
15:20  15:40  The absolute photon flux of a nitrogen vacancy center based singlephoton Marco Lopez PhysikalischTechnische Bundesanstalt, Bundesallee 100, D38116, Braunschweig, Germany Singlephoton sources are considered being one of the key components in several quantumbased technologies, such as quantum communication and quantum key distribution. Furthermore, singlephoton sources are of highest interest for application as standard sources also in radiometry. Here, they have the potential to be applied for the calibration of singlephoton detectors or as noisereduced sources. For the characterization of a singlephoton source, besides emission wavelength and single photon purity (i.e. the g(2)(0)value), the absolute emitted photon flux is an important parameter. At PTB, the spectral photon flux and the spectral radiant flux of a nitrogenvacancy center based singlephoton source was determined traceable to national standards, i.e. to the cryogenic radiometer (for the absolute photon flux) and to the blackbody radiator (for the spectral power distribution). A complete metrological characterization of the source was carried out, including a detailed measurement analysis for the spectral photon flux. The relative standard uncertainty is determined to be 4 %, dominated by the determination of the relative spectral power distribution. In addition, the angular emission pattern was measured and compared to calculations based on the model of Lukosz and Kunz. We consider these investigations and the obtained results as a very important step towards the realization of a pure quantumbased radiation standard. 
15:40  16:00  Generator of arbitrary classical photon statistics Ivo Straka, Jaromír Mika, Miroslav Ježek Department of Optics, Faculty of Science, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic We propose and experimentally demonstrate a device for generating light with arbitrary classical photonnumber distribution. We use programmable acoustooptical modulation to control the intensity of light within the dynamic range of more than 30 dB and interlevel transitions faster than 500 ns with further speedup possible by employing electrooptical modulation. We propose a universal method that allows highfidelity generation of userdefined photon statistics. Extremely high precision <0.001 can be reached for lower photon numbers, and faithful tail behavior can be reached for very high photon numbers. We demonstrate arbitrary statistics generation for up to 500 photons. For detection, we employ an avalanche diode that allows us sufficient photonnumber resolution in the time domain. The proposed device can produce any classical light statistics with given parameters including Poissonian, superPoissonian, thermal, and heavytailed distributions like lognormal. The presented methods can be used to simulate communication channels, calibrate the response of photonnumberresolving detectors, or probe physical phenomena sensitive to photon statistics. [1] I. Straka, J. Mika, and M. Ježek, arXiv:1801.03063 (2018). 
16:00  16:35  COFFEE BREAK 
Session: EntanglementChair: Ivo Degiovanni  
16:35  17:05  The dawn of quantum networks Ronald Hanson QuTech and Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands Entanglement – the property that particles can share a single quantum state  is arguably the most counterintuitive yet potentially most powerful element in quantum theory. The nonlocal features of quantum theory are highlighted by the conflict between entanglement and local causality discovered by John Bell. Decades of Bell inequality tests, culminating in a series of loopholefree tests in 2015, have confirmed the nonlocality of Nature. Future quantum networks may harness these unique features of entanglement in a range of exciting applications, such as distributed quantum computation, secure communication and enhanced metrology for astronomy and timekeeping. To fulfill these promises, a strong worldwide effort is ongoing to gain precise control over the full quantum dynamics of multiparticle nodes and to wire them up using quantumphotonic channels. Diamond spins associated with NV centers are promising building blocks for such a network as they combine a coherent electronoptical interface with a local register of robust and wellcontrolled nuclear spin qubits. Here I will introduce the field of quantum networks and discuss ongoing work with the specific target of realizing the first multinode network wired by quantum entanglement. 
17:05  17:25  Quantum Logic and Photon Steering with Single Cavity Photons in Integrated Photonic Circuits Axel Kuhn^{1}, Thomas Barrett^{1}, Marwan Mohammed^{1}, Naomi Holland^{1}, Thomas Doherty^{1}, Klara Theophilo^{1}, Allison Rubenok^{2}, Jonathan Matthews^{2}, Oliver Barter^{1}, Dustin Stuart^{1} ^{1}University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK We demonstrate quantum logic and quantum feedback using narrow linewidth photons that are produced with an apriori nonprobabilistic scheme from a single rubidium atom strongly coupled to a highfinesse cavity [1]. We use a controlledNOT gate integrated into a photonic chip to entangle these photons [2], and we observe nonclassical correlations between photon detection events separated by periods exceeding the travel time across the chip by three orders of magnitude. Furthermore we apply a quantumfeedback scheme in a twophoton interference setting that allows deliberate switching between bosonic and fermionic photon behaviour, thus steering the 2nd photon in a HongOuMandel twophoton interferometer to an arbitrarily chosen output port [3]. Next steps to be taken to push the present stateoftheart to a fully scalable quantum network will be briefly mentioned, see e.g. [4], and explored in detail by my coworkers with their own contributions. [1] A. Kuhn, Cavity Induced Interfacing of Atoms and Light, in Engineering the AtomPhoton Interaction, Springer (2015) [2] A. Holleczek et al., Phys. Rev. Lett. 117, 023602 (2016) [3] O. Barter et al., in preparation. [4] D. Stuart and A. Kuhn, New. J. Phys. 20, 023013 (2018) 
17:25  17:45  Precise characterization of BraggReflection Waveguides for producing versatile polarizationentangled states K. Laiho^{1}, B. Pressl^{2}, A. Schlager^{2}, S. Auchter^{2}, H. Chen^{2}, T. Günthner^{2}, H. Suchomel^{3}, J. Gessler^{3}, M. Kamp^{3}, S. Höfling^{3,4}, C. Schneider^{3}, G. Weihs^{2} ^{1}Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany Semiconductor Braggreflection waveguides (BRWs) emit correlated photon pairs called signal and idler via parametric downconversion (PDC). In order to fulfill the necessary energy and momentum conservation in these highly dispersive platforms, one of the modes, in our case the pump, is a higher order spatial mode. To achieve this, BRWs are compounded of thin layers of AlGaAs with different thicknesses and aluminum concentrations and fabricated with standard semiconductor growth techniques. Several BRW characteristics such as their total nonlinearity and final PDC wavelength are highly sensitive to the fabrication tolerances in the structure's parameters. Our simulations show that, if not taken care of, one can easily result into samples with properties far away from the design parameters [1]. We then experimentally measure the group refractive indices of the interacting modes that dominate the joint spectral properties of signal and idler, produce broadband indistinguishable photon pairs and prepare polarization entangled states. By modifying the temporal delay between signal and idler we can flexibly vary the degree of entanglement directly at the source [2]. Our results show that BRWs are a versatile source for different quantum optics tasks and thus, can become truly practical in the integrated quantum photonics. [1] B. Pressl, K. Laiho, H. Chen, T. Günthner, A. Schlager, S. Auchter, H. Suchomel, M. Kamp, S. Höfling, C. Schneider and G. Weihs, Quantum Sci. Technol. 3, 024002 (2018). [2] A. Schlager, B. Pressl, K. Laiho, H. Suchomel, M. Kamp, S. Höfling, C. Schneider and G. Weihs, Opt. Lett. 42, 2102 (2017). 
17:45  18:05  Polarised SinglePhotons from a CavityEnhanced AtomLight Interface in Photonic Quantum Networks Thomas Barrett^{1}, Oliver Barter^{1}, Dustin Stuart^{1}, Allison Rubenok^{2}, Jonathan Matthews^{2}, Axel Kuhn^{1} ^{1}University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK Entanglement is a key resource for quantum information processing (QIP). Mutually entangled cluster states are inherently more robust than pairwise chains of entangled qubits, however it is particularly difficult to create these in nonlocal networks where bringing together distant nodes is often impractical. Instead quantum networks of interlinked stationary (typically single atoms or ions) and flying (photonic) qubits offer a scalable route to bridging these physical distances [1], but necessitate a reliable interface between these quantum elements. A single atom strongly coupled to a single mode of the electric field, where the internal spin state of the atom is entangled to the emitted photon polarisation, is then an ideal architecture for realising such a system. Probabilistic entanglement of distant atoms can be achieved by entanglement swapping acting on photons emitted from both atoms [2,3]. Here we discuss the essential first step, an a priori nonprobabilistic source of polarised singlephotons, that utilises the unparalleled control over the photonic states provided by the cavityenhanced interaction with a single ^{87}Rb atom [4]. In particular we consider novel effects of nonlinear Zeeman shifts on this system and the operation of a 4x4 multimode interferometer integrated onto a photonic chip [5] with pairs of cavityphotons. [1] S. Ritter, C. Nolleke, C. Hahn, A. Reiserer, A. Neuzner, M. Uphoff, M. Mucke, E. Figueroa, J. Bochmann, and G. Rempe, Nature, 484, 195 (2012). [2] D. Moehring, P. Maunz, S. Olmschenk, K. Younge, D. Matsukevich, L.M. Duan, and C. Monroe, Nature, 449, 68 (2007). [3] S. Olmschenk, D. Matsukevich, P. Maunz, D. Hayes, L.M. Duan, and C. Monroe, Science, 323, 486 (2009). [4] A. Kuhn, Cavity Induced Interfacing of Atoms and Light; in Engineering the AtomPhoton Interaction, Edts M. Mitchel and A. Predojevic, Springer (2015). [5] A. Peruzzo, A. Laing, A. Politi, T. Rudolph, and J. L. O'Brien, Nature Communications, 2, 224 (2011) 
18:30  …  WELCOME RECEPTION 
Session: Single Photon Sources IChair: Andrew Shields  
09:00  09:30  Deterministic generation of a cluster state of entangled photons, using semiconductor quantum dots David Gershoni The Physics Department and the Solid State Institute, Technion – Israel Institute of Technology, Haifa, 32000, Israel Photonic cluster states are a resource for quantum computation based solely on singlephoton measurements. We use semiconductor quantum dots to deterministically generate long strings of polarizationentangled photons in a cluster state by periodic timed excitation of a precessing matter qubit. In each period, an entangled photon is added to the cluster state formed by the matter qubit and the previously emitted photons. In our prototype device, the qubit is the confined dark exciton, and it produces strings of hundreds of photons in which the entanglement persists over five sequential photons. 
09:30  09:50  A Bright Triggered TwinPhoton Source in the Solid State Tobias Heindel^{1}, Alexander Thoma^{1}, Martin von Helversen^{1}, Marco Schmidt^{1,2}, Alexander Schlehahn^{1}, Manuel Gschrey^{1}, Peter Schnauber^{1}, JanHindrik Schulze^{1}, André Strittmatter^{1,4}, Jörn Beyer^{2}, Sven Rodt^{1}, Alexander Carmele^{3}, Andreas Knorr^{3}, Stephan Reitzenstein^{1} ^{1}Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany The realization of integrated light sources capable of emitting nonclassical multiphoton states, is a fascinating, yet equally challenging task at the heart of quantum optics [1]. In this work, we propose and experimentally demonstrate the triggered generation of photon twins by exploiting the energydegenerate biexcitonexciton (XXX) radiative cascade of semiconductor quantum dots (QDs) [2]. For this purpose, we select QDs featuring E_{X}^{H} = E_{XX}^{H}, which implies a matching between the fine structure splitting and the biexciton binding energy (ΔE_{FSS} = E_{bin}^{XX}). In this case, one decay channel of the XXX cascade reveals the emission of photontwins – a light state which is comprised of two temporally correlated photons with identical emission energy and polarization. Deterministically integrated within a microlens, this system emits highlycorrelated photon pairs at a rate of up to (234 ± 4) kHz. Furthermore, we employ a photonnumberresolving detector to directly observe the twinphoton state, which enables a reconstruction of the photon number distribution of our source. In conclusion, the twinphoton source presented in this work is an attractive type of integrated quantum light source, which might be exploited in emerging research fields, such as quantumoptical spectroscopy or quantum biology, which benefit from multiphoton excitation schemes. [1] R. Loudon, The Quantum Theory of Light, Oxford Science Publications (1983). [2] T. Heindel et al., Nat. Commun. 8, 14870 (2017). 
09:50  10:10  Generation of singlephoton and twophoton pulses from a quantum twolevel system Lukas Hanschke^{1}, Kevin A. Fischer^{2}, Jakob Wierzbowski^{1}, Tobias Simmet^{1}, Constantin Dory^{2}, Jonathan J. Finley^{1}, Jelena Vuckovic^{2}, Kai Müller^{1} ^{1}Walter Schottky Institut and Physik Department, Technische Universität München, 85748 Garching, Germany Resonantly excited twolevel systems are poised to serve the pivotal role of ondemand singlephoton sources. Here, we demonstrate that a twolevel system can surprisingly also operate in a twophoton bundling regime. Our system is an excitonic transition in a selfassembled quantum dot. For singlephoton generation, it is typically excited with a resonant pulse of area π. This prepares the system in its excited state from where it spontaneously emits a single photon. However, emission that occurs during the presence of the laser pulse allows for reexcitation and, thus, multiphoton emission which spoils the singlephoton character [1]. In contrast, when exciting with a pulse of area 2π, the system is expected to be returned to the ground state. However, emission during the presence of the pulse is most likely to occur when the system is in its excited state – exactly after an area of π was absorbed. This restarts the Rabi oscillation with a pulse area of π remaining in the pulse, leading to reexcitation with nearunity probability and the emission of a second photon within the excited state lifetime [2]. [1] K.A. Fischer et al. NJoP 18, 113053 (2016) [2] K.A. Fischer et al. Nature Physics 13, 649654 (2017) 
10:10  10:30  852nm Triggered Single Photons from a Single Cesium Atom Trapped in a Microscopic Optical Tweezer with Magic Wavelength Jun HE^{1, 2}, Jiachao WANG^{1}, Rui SUN^{1}, Kong ZHANG^{1}, Junmin WANG ^{1, 2} ^{1}State Key Laboratory of Quantum Optics and Quantum Optics Devices,and Institute of OptoElectronics, Shanxi University, P. R. China Atoms trapped in the magicwavelength optical tweezer will have the same light shift for the ground state and the excited state. Therefore the positiondependence differential light shift of the desired transition can be eliminated in the case of magicwavelength optical tweezer. Based on the multilevel atomic model, we have calculated the magic wavelength for the Zeeman sublevels of the ground state 6S_{1/2} and the excited state 6P_{3/2} of cesium atoms. For cesium 6S_{1/2} Fg = 4, mF = +4>  6P_{3/2} Fe = 5, mF = +5> cycling transition, the magic wavelength was founded to be 937.7nm for a linearly polarized tweezer. And it has also been experimentally verified by using of the laserinduced fluorescence spectra of trapped single cesium atoms in a tweezer. Compared to the transition frequency in the free space, the differential light shift was measured to be about 0.7 MHz in the 937.7 nm linearlypolarized tweezer, which is about 1.2% of the trap depth. We have also investigated the effects of polarization of tweezer beam, bias magnetic field, and effective temperature of single cesium atoms upon the measurement results. We have demonstrated 852 nm triggered singlephoton source based on single cesium atom trapped in a microscopic optical tweezer. And the two cases of 1064 nm and 937.7 nm (the magic wavelength) linearlypolarized tweezers are compared experimentally. The photon statistics show strong antibunching effect with typical g^{2}(0) ~ 0.09, which clearly indicates the singlephoton characters. The distinguishability of single photons is expected to be improved for the magicwavelength optical tweezer. The HongOuMandel twophoton interference measurement is employed to evaluate the photon distinguishability. [1] Phys. Rev. A, Vol.94 (2016) 013409 [2] Opt. Express, Vol.25 (2017) p.15861. 
10:30  11:05  COFFEE BREAK 
Session: Quantum Communications & QKDChair: Christine Silberhorn  
11:05  11:35  Quantum Communication Networks Andrew Shields Toshiba Research Europe Ltd, UK Applying quantum theory to information systems brings new functionalities that are not possible in conventional networks and computers. For example, the secrecy of encoded single photons transmitted along optical fibres can be tested directly and used to distribute cryptographic keys and digital signatures on communication networks. In this talk I will discuss recent work to realise practical systems for quantum key distribution (QKD) and their application to pointtopoint and networkbased encryption. The past few years have seen rapid progress in the technology required to operate QKD in conventional data networks. I will discuss advances on increasing the secure key rate above 10 Mb/s, extending the range of a single link, enabling the coexistence of QKD with very high (Tb/s) data bandwidths on the same fibre and introducing QKD to multiuser access networks that can dramatically reduce the cost. This will be illustrated with examples of real world deployment of the technology on installed fibres and networks. I will also discuss recent work on realizing next generation quantum networks based on distributed entanglement. 
11:35  11:55  Quantum interference with frequencylocked dissimilar light sources Chris Müller, Tim Kroh, Yanting Teng, Andreas Ahlrichs, Oliver Benson HumboldtUniversität zu Berlin, Institut für Physik, Newtonstraße 15, 12489 Berlin, Germany Quantum communication requires a suitable network consisting of quantum nodes and quantum channels [1]. For such a quantum network to be realized, it will be necessary to process, store, and send photons over long distances. It is unlikely that a single physical system can perform all these operations at the same time. Therefore, it will be required to connect different quantum systems within future quantum networks. This can be achieved via twophoton measurements and entanglement swapping [2]. A key requirement, however, is that the two different quantum systems emit indistinguishable photons. This can be checked by measuring HongOuMandel (HOM) interference [3]. In our HOM experiment we interfere photons from two dissimilar sources: one pairphoton from cavityenhanced spontaneous parametric downconversion [4] and the other from a semiconductor quantum dot [5]. Active frequencylocking is mandatory to allow for data accumulation over a sufficiently long time and for further expanding the quantum network by additional units. We discuss achievable degrees of indistinguishability and estimate the success rate of future transfer of electronic states in quantum dots over long distances including frequency conversion to the telecom band [6].
[1] Kimble, Nature 453, 1023 (2008) [2] Huwer et al., Phys Rev. Appl. 8, 024007 (2017) [3] Hong et al., Phys. Rev. Lett. 59, 2044 (1987) [4] Ahlrichs and Benson, Appl. Phys. Lett. 108, 021111 (2008) [5] Rastelli et al., Physica Status Solidi B 249, 687 (2012) [6] Kroh et al., Quantum Sci. Technol. 2, 034007 (2017) 
11:55  12:15  Experimental demonstration of remote temporal wavepacket narrowing Karolina Sedziak, Mikolaj Lasota, Piotr Kolenderski Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87100 Torun, Poland We will present the problem of wavepacket shaping of a single photon which is heralded by the timeresolved detection of the other photon from an SPDC pair. The strength of the wavepacket narrowing depends on the parameters of the photon pair source and the width of the detection window for the heralding photon. Our theoretical predictions [1] were compared with the experimental results [2] showing very good agreement. We measured the reduction of the width of the heralded wavepacket to approximately 29% as compared to the case of nonheralding scenario. The results can be utilized to improve quantum communication and clock synchronization protocols. [1] K. Sedziak, M. Lasota, P. Kolenderski, “Reducing detection noise of a photon pair in a dispersive medium by controlling its spectral entanglement,” Optica 4, 84 (2017). 
12:15  12:35  Towards heterogeneous quantum networks with solid state single photon sources and atomic quantum memories Wolters^{1}, Buser^{1}, Béguin^{1}, Mottola^{1}, Jahn^{1}, Horsley^{1}, Benson^{2}, Warburton^{1}, Treutlein^{1} ^{1}Universität Basel, Department Physik, Klingelbergstr. 82 4056 Basel, Switzerland Quantum networks promise a plethora of radically new applications and novel insights [1]: Highspeed quantum cryptography networks will be used for unconditional secure communication in metropolitan areas, and memory enhanced quantum computers and simulators will allow for exponential speedup in solving complex problems [2]. However, establishing the hardware for a quantum network is a challenging task. A source of indistinguishable single photons is required, along with means to store the single photons at each node [3]. We report on our concentrated efforts to build the basic element of quantum networks, i.e. a semiconductor quantum dot (QD) single photon source [4,5] coupled to a compatible atomic quantum memory [6]. On the one hand we demonstrate a rubidium quantum memory for broadband operation, matched to the QD exciton natural decay rate. The memory is demonstrated using attenuated laser pulses on the single photon level with a bandwidth of 0.66 GHz. In the present memory, the readout noise is dominated by atomic fluorescence, and for input pulses containing on average μ1 = 0.27(4) photons the signal to noise level would be unity. On the other hand, we demonstrate deterministic single photon shaping with QDs, to match the narrow atomic transitions of Rubidium [7]. [1] H.J. Kimble, “The quantum internet,” Nature 453, 1023 (2008). [2] T. D. Ladd et al., “Quantum computers,” Nature 464, 45 (2010). [3] N. Sangouard et al., “Quantum repeaters based on atomic ensembles and linear optics,” Rev. Mod. Phys. 83, 33 (2011). [4] J.P. Jahn et al., “An artificial Rb atom in a semiconductor with lifetimelimited linewidth,” Phys. Rev. B 92, 245439 (2015). [5] L. Beguin et al., “Ondemand semiconductor source of 780 nm single photons with controlled temporal wave packets,” arXiv:1710.02490 (2017). [6] J. Wolters et al., “Simple atomic quantum memory suitable for semiconductor quantum dot single photons,” Phys. Rev. Lett. 119 060502 (2017). [7] L. Béguin et al., Ondemand semiconductor source of 780 nm sin gle photons with controlled temporal wave packets, arXiv:1710.02490 (2017). 
12:35  12:45  GROUP PICTURE 
12:45  14:15  LUNCH BREAK 
Session: Integrated Photonic CircuitsChair: David Gershoni  
14:15  14:45  Nonlinear integrated quantum optics Christine Silberhorn University of Paderborn, Germany Recent achievements in the area of integrated quantum optics and quantum information processing have shown impressive progress for the implementation of linear circuits based on monolithic waveguide structrues. However, most experiments are based on χ^{(3)} media, such as glas, siliconon insulator or silicaonsilicon. In these platforms the implentation of highly efficient sources, frequency converters and fast active phase shifters and modulators pose severe challenges.The use of advanced waveguides structures, which harness a χ^{(2)} –nonlinearity, allows for the realization various devices with multiple functionalites. These include single and multichannel sources with extraordinary brightness, quantum frequency conversion with tailored spectraltemporal properties, and complex circuitries comprising degenerate pair generation in orthogonal polarization, linear elements, and active elements such as polarization rotators or an electrooptically controllable time delay. Here we present several different examples of integrated devices based on χ^{(2)} –media for the implementation of advanced, integrated photon pair sources and quantum circuits. 
14:45  15:05  Deterministic integration of quantum dots into onchip MMI couplers via insitu electron beam lithography Peter Schnauber^{1}, Johannes Schall^{1}, Samir Bounouar^{1}, Theresa Höhne^{2}, SukIn Park^{3}, GeunHwan Ryu^{3}, Tobias Heindel^{1}, Sven Burger^{2}, JinDong Song^{3}, Sven Rodt^{1}, Stephan Reitzenstein^{1} ^{1}Technische Universität Berlin, Berlin, Germany The deterministic integration of quantum emitters into onchip photonic elements is crucial for the implementation of scalable onchip quantum circuits. Recent activities in this field include hybrid QDwaveguides for enhanced photon incoupling [1] and first, rather tedious steps towards the controlled integration of QDs using multisteplithography [2] as well as AFM tip transfer [3]. Here we report on the deterministic integration of single quantum dots (QD) into onchip beam splitters using insitu electron beam lithography (EBL) [4]. In this singlestep technique, photonic building blocks are patterned on top of chosen QDs immediately after spatially and spectrally precharacterizing them through their cathodoluminescence signal [5]. To realize 50/50 coupling elements acting as central building blocks of onchip quantum circuits we chose tapered multimode interference (MMI) splitters which feature relaxed fabrication tolerances and robust 50/50 splitting ratio. We demonstrate the functionality of the deterministic QDwaveguide structures by highresolution µPL spectroscopy and by studying the photon crosscorrelation between the two MMI output ports. The latter confirms singlephoton emission and onchip splitting associated with g(2)(0) < 0.5. [1] M. Davanco, J. Liu, L. Sapienza, C.Z. Zhang, J. V. M. Cardoso, V. V., R. Mirin, S. W. Nam, L. Liu, K. Srinivasan, Nature Communications, 8, 889 (2017) [2] R. J. Coles, D. M. Price, J. E. Dixon, B. Royall, E. Clarke, P. Kok, M. S. Skolnick, A. M. Fox, M. N. Makhonin, Nature Communications 7, 11183 (2016) [3] J.H. Kim,S. Aghaeimeibodi, C. J. K. Richardson, R. P.Leavitt, D. Englund, E. Waks, Nano Letters 17 (12), 7394 (2017) [4] P. Schnauber, J. Schall, S. Bounouar, T. Höhne, S.I. Park, G.H. Ryu, T. Heindel, S. Burger, J.D. Song, S. Rodt, S. Reitzenstein, arXiv 1712.03837 (2017) [5] M. Gschrey, A. Thoma, P. Schnauber, M. Seifried, R. Schmidt, B. Wohlfeil, L. Krüger, J.H. Schulze, T. Heindel, S. Burger, F. Schmidt, A. Strittmatter, S. Rodt, S. Reitzenstein, Nature Communications 6, 7662 (2015) 
15:05  15:25  Superconducting nanowire singlephoton detectors on GaAs with suppressed parasitic counts Ekkehart Schmidt^{1}, Mario Schwartz^{2}, Florian Hornung^{2}, Ulrich Rengstl^{2}, Stefan Hepp^{2}Konstantin Ilin^{1}, Simone L. Portalupi^{2}Michael Jetter^{2}, Peter Michler^{2}, Michael Siegel^{1} ^{1}Institute of Micro und Nanoelectronic Systems (IMS), Karlsruhe Institute of Technology, Karlsruhe, Germany An onchip quantum photonic device consists of quantum dots, waveguide based logic and SNSPD. The quantum dots are conveniently excited by a laser beam [1][2]. Stray flux of these exciting photons can be detected by the SNSPD and therefore causes the malfunction of the whole photonic circuit. We studied the efficiency of suppression of parasitic detector counts using an onchip mirror. The SNSPDs were made from 6 nm thin NbN film deposited by reactive magnetron sputtering onto GaAs substrate with a 12 nm thick AlN buffer layer. Two identical SNSPDs were fabricated from the same NbN film at a distance of 50 µm from each other. The 120 nm wide nanowires are of a critical temperature of 9.9 K and a critical current density of 2.8 MA/cm^{2} at 4.2 K. One of these SNSPDs was covered with a bilayer of 20 nm thick AlN and 110 nm thick Al forming an onchip mirror which significantly decreased the amount of parasitic counts seen at the detector. This technology could enable a fully onchip HanburyBrown and Twiss experiment when combined with a singlemode waveguide based coupler and an integrated quantum dot singlephoton source [2,3]. [1] G. Reithmaier, S. Lichtmannecker, T. Reichert, P. Hasch, K. Müller, M. Bichler, R. Gross & J. J. Finley: Onchip time resolved detection of quantum dot emission using integrated superconducting single photon detectors, Scientific Reports 3 (2013), Article number: 1901 [2] M. Schwartz, U. Rengstl, T. Herzog, M. Paul, J. Kettler, S. Luca Portalupi, M. Jetter & P. Michler: Generation, guiding and splitting of triggered single photons from a resonantly excited quantum dot in a photonic circuit, Optics Express Vol. 24, Issue 3 (2016), 30893094 [3] U. Rengstl, M. Schwartz, T. Herzog, F. Hargart, M. Paul, S. L. Portalupi, M. Jetter and P. Michler: Onchip beamsplitter operation on single photons from quasiresonantly excited quantum dots embedded in GaAs rib waveguides,Appl. Phys. Lett. 107, 021101 (2015) 
15:25  15:45  IIIV integrated photonic circuits for the generation and manipulation of quantum states of light Jonathan Belhassen^{1}, Saverio Francesconi^{2}, Qifeng Yao^{3}, Ivan Favero^{4}, Aristide Lemaître^{5}, Steve Kolthammer^{6}, Ian Walmsley^{7}, Maria Amanti^{8}, Florent Baboux^{9}, Sara Ducci^{10} ^{1}jonathan.belhassen05@gmail.com Photonic circuits provide a promising approach to achieving a wide range of quantum information tasks. Rapid progress has been made in recent years to develop circuits implementing the key ingredients of quantum information. A next important step towards largescale applications will now be to develop active photonic circuits capable of generating and manipulating quantum states in an integrated manner. Here we report the first realization of a monolithic IIIV photonic circuit combining a parametric heralded singlephoton source with a beam splitter [1]. Pulsed parametric downconversion in an AlGaAs waveguide generates counterpropagating photons, one of which is used to herald the injection of its twin into the beam splitter, consisting of a multimode interferometer. This configuration allows us to realize an integrated HanburyBrown and Twiss experiment which confirms singlephoton generation and manipulation, at room temperature and telecom wavelength. After this first demonstration we are now working on the manipulation of more complex quantum states. In particular, we tailor biphoton frequency entanglement through amplitude and phase engineering of the pump beam with an SLM [2]. Original quantum states featuring nonGaussian entanglement are generated, illustrating the potential of the IIIV platform for the control of highdimensional entanglement. [1] J. Belhassen et al., arXiv:1710.08710, to appear in Applied Physics Letters. [2] S. Francesconi et al., in preparation. 
15:45  16:00  COFFEE BREAK 
16:00  18:30  POSTER SESSION 
Session: Quantum SensingChair: Mark Fox  
09:00  09:30  Magnetic sensing using quantum defects in diamond Ronald Walsworth Harvard University, Cambridge, USA Nitrogen vacancy (NV) quantum defects in diamond provide an unparalleled combination of magnetic field sensitivity and spatial resolution in a roomtemperature solid, with wideranging applications in both the physical and life sciences. NVs can be brought into few nanometer proximity of magnetic field sources of interest — such as single protons and electrons — while maintaining long NV spin coherence times, a large (~Bohr magneton) Zeeman shift of the NV spin states, and optical preparation and readout of the NV spin. Recent applications include mapping magnetic signatures in >4 billionyearold meteorites and earlyEarth rocks that inform theories of solar system and Earth formation, noninvasive magnetic sensing of single neuron action potentials, measuring the spin chemical potential in magnetic devices, and NMR chemical fingerprinting at the scale of a single biological cell. I will provide an overview of this technology and its diverse applications. 
09:30  09:50  High resolution sensing of highfrequency fields with continuous dynamical decoupling Alexander Stark^{1,3}, Nati Aharon^{2}, Thomas Unden^{3}, Daniel Louzon^{2,3}, Alexander Huck^{1}, Alex Retzker^{2}, Ulrik Lund Andersen^{1}, Fedor Jelezko^{3} ^{1}Department of Physics, Technical University of Denmark, Fysikvej, Kongens Lyngby 2800, Denmark Stateoftheart methods for sensing weak AC fields are only efficient in the low frequency domain (<10 MHz). The inefficiency of sensing highfrequency signals is due to the lack of ability to use dynamical decoupling. In this work we show that dynamical decoupling can be incorporated into highfrequency sensing schemes and by this we demonstrate that the high sensitivity achieved for low frequency can be extended to the whole spectrum [1]. While our scheme is general and suitable to a variety of atomic and solidstate systems, we experimentally demonstrate it with the nitrogenvacancy center in diamond. We achieve coherence times up to 1.43 ms resulting in a smallest detectable magnetic field strength of 4 nT at 1.6 GHz. Attributed to the inherent nature of our scheme, we observe an additional increase in coherence time due to the signal itself. In this talk I will also present a few other dynamical decoupling schemes [24], as well as our recent results [5], that could be utilized to further improve the resolution of sensing oscillating signals, and in particular, high frequency fields. [1] A. Stark, N. Aharon, T. Unden, D. Louzon, A. Huck, A. Retzker, U.L. Andersen, and F. Jelezko, Nat. Commun. 8, 1105 (2017). [2] N. Aharon, I. Cohen, F. Jelezko, and A. Retzker, New J. Phys. 18 123012 (2016). [3] I. Cohen., N. Aharon, and Alex Retzker, Fortschritte der Physik 64 (2016). [4] D. Farfurnik, N. Aharon, I. Cohen, Y. Hovav, A. Retzker, N. BarGill, Phys. Rev. A 96, 013850 (2017). [5] A. Stark, N. Aharon, A. Huck, A. Retzker, F. Jelezko, and U.L. Andersen, in preparation.

09:50  10:10  Ghost Modalities with thermal light emitted from a broadband superluminescent diode light source: ghost imaging, ghost spectroscopy and ghost polarimetry Wolfgang Elsäßer, Patrick Janassek, Sébastien Blumenstein Institute of Applied Physics, Technische Universität Darmstadt, Schlossgartenstrasse 7, 64289 Darmstadt (Germany) Ghost imaging (GI) is by far not a “spooky action” but rather a photon correlation imaging modality based on the fundamentals of quantum optics, either realized with entangled photons in the quantum GI version or with bunched photons from classical thermal sources.
Here, we introduce to the field of ghost modalities a novel, extremely compact ultraminiaturized superluminescent diode source based on Amplified Spontaneous Emission (ASE). We demonstrate a GI experiment with classical thermal light based on the full incoherence of light as requested for classical GI, namely in 1st order coherence being spectrally broadband, in 2nd order coherence exhibiting HanburyBrown & Twiss photon bunching with a correlation coefficient of two and being spatially incoherent due to the dynamic mode filamentation.
We then extend the field of ghost modalities in analogy to this classical spatial GI principle with classical light to ghost spectroscopy. We propose and realize a first ghost spectroscopy (GS) experiment with classical thermal light by exploiting spectral correlations of light emitted by a broadband semiconductorbased superluminescent diode (SLD) and demonstrate the applicability of this ghost modality in a realworld proofofprinciple experiment by measuring a ghost absorption spectrum a(l) of the characteristic absorption features of chloroform at 1214nm, i.e. a ghost spectrum. S. Hartmann and W. Elsäßer, Sci. Rep. 7, 41866 (2017) P. Janassek, S. Blumenstein, and W. Elsäßer, Phys. Rev. Appl. 9, Feb. 2018 
10:10  10:30  Experimental studies of quantum plasmonic sensing Changhyoup Lee^{1}, Mark Tame^{2,3}, KwangGeol Lee^{4}, Xifeng Ren^{5,6}, Carsten Rockstuhl^{1,7} ^{1}Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany Plasmonic systems that support surface plasmon polaritons provide one of the most practical sensing platforms, where the extreme fieldconfinement below the diffraction limit greatly enhances sensitivity. The associated sensing uncertainty, however, is fundamentally limited by the statistical nature of classical light, known as the shotnoise limit. Recent experimental works have shown the possibility of reducing quantum noise in plasmonic sensing by employing quantum resources [1,2,3]. More theoretical investigations have offered better understanding for separate roles of quantum resources and implemented plasmonic features in the context of quantum sensing [4,5]. In this work, we experimentally studied sensing performances of two types of quantum plasmonic sensors: a plasmonic nanowire and an attenuatedtotalreflection prism setup for which the illumination are a twophoton N00N state and twomode squeezed state, respectively. Our work aims achieving a sensing uncertainty below the shot noise limit on scales below the diffraction limit. We show that quantum benefits such as superresolution and quantum noisereduction are achieved even in the presence of metallic losses. With our experimental studies of quantum plasmonic sensors, we envisage that progress in quantum metrology will reshape the field of plasmonic biosensing  a field that has already developed into mature technology for a few decades. [1] D. A. Kalashnikov, Z. Pan, A. I. Kuznetsov, and L. A. Krivitsky, Phys. Rev. X 4, 011049 (2014). [2] W. Fan, B. J. Lawrie, and R. C. Pooser, Phys. Rev. A 92, 053812 (2015). [3] R. C. Pooser and B. Lawrie, ACS Photonics 10, 1021 (2015). [4] C. Lee, F. Dieleman, J. Lee, C. Rockstuhl, S. A. Maier, and M. Tame, ACS Photonics 3, 992 (2016). [5] J.S. Lee, T. Hyunh, S.Y. Lee, K.G. Lee, J. Lee, M. Tame, C. Rockstuhl, and C. Lee, Phys. Rev. A 96, 033833 (2017). 
10:30  11:05  COFFEE BREAK 
Session: Single Photon Sources IIChair: Varun Verma  
11:05  11:35  Onchip quantum photonics with integrated quantumdot singlephoton sources A.M. Fox University of Sheffield, Sheffield, U.K. Onchip quantum photonics relies on the integration of efficient singlephoton sources with advanced quantumoptical circuits. In this presentation, I will review progress at the University of Sheffield on a chipcompatible IIIV semiconductor platform in which quantumdot (QD) singlephoton sources are integrated into GaAs photonic circuits. I will first describe work demonstrating singlephoton emission and interference using a quantum dot source integrated with a monolithic onchip Hanbury BrownTwiss interferometer. I will then describe the development of an electrically pumped singlephoton source integrated with a nanobeam waveguide, and a highspeed, high coherence source using an InGaAs QD coupled to an H1 photonic crystal nanocavity. Under resonant πpulse excitation, an onchip, ondemand singlephoton source exhibiting high purity and indistinguishability has been demonstrated without spectral filtering. Finally, I will discuss chiral coupling between QD single photon sources and nanophotonic waveguides, which is a manifestation of chiral quantum optics. Experiments demonstrating both chiral emission and exciton spin initialization will be described. These results rely on the precise positioning of dot within the nanophotonic structure, and lay the foundations for developing onchip spin networks with spin qubits localized in different QDs. 
11:35  11:55  Amir Tavala, Wien, Austria (Student Award) Quantum optical source for probing retina response to single photons 
11:55  12:15  Purification of single photons by temporal heralding of quantum dot sources Hamza Abudayyeh^{1,2}, Boaz Lubotzky^{1,2}, Jennifer Hollingsworth^{3}, Ronen Rapaport^{1,2,4} ^{1}Racah Institute for Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel Nanocrystal quantum dots (NQDs) are excellent candidates for room temperature single photon sources (SPSs) due to their relative ease of fabrication, emission spectrum tunability, and scalability. However recent efforts in stabilizing NQDs have resulted in a significant increase in biexciton emission compromising their integrity as possible SPSs and leading to a tradeoff between single photon purity and stability. Temporal filtering was suggested to dispose of the biexciton emission altogether but this lead to a significant decrease in efficiency. In this work we suggest three heralding techniques that would break this threeway compromise between purity, efficiency and stability. Using these techniques we were able to theoretically show that stable NQDs (with high biexciton quantum yields) can be used as a source for heralded single photons with efficiencies and purities approaching unity. Furthermore we confirm our theoretical prediction with a proof of concept experiment on a single core/thickshell NQD. 
12:15  12:35  Singlephoton generation from GaAsbased deterministic QDmesas at telecom wavelengths. Anna Musiał^{1}, Łukasz Dusanowski^{1}, Paweł Holewa^{1}, Paweł Mrowiński^{1}, Aleksander Maryński^{1}, Krzysztof Gawarecki^{2}, Tobias Heuser^{3}, Nicole Srocka^{3}, David Quandt^{3}, André Strittmater^{3}, Sven Rodt^{3}, Stephan Reitzenstein^{3}, Grzegorz Sęk^{1} ^{1}OSN Laboratory, Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, Wrocław, Poland Epitaxial semiconductor quantum dots (QDs) have been proven powerful and versatile platform to study quantum optics phenomena and realize quantum optical devices. The next step is to bring them towards practical applications. In the case of QDbased singlephoton sources the challenges are: enhance extraction efficiency to obtain high rate of single photons on demand, increase the operation temperature towards cryogenicfree cooling systems, realize single QDnanophotonic structures for high purity singlephoton generation in the deterministic technology and employ electrical excitation as well as compact designs compatible with fiber networks. We present our progress in realization of compact fiberbased singlephoton source at telecom wavelengths based on strainengineered InGaAs/GaAs MOCVDgrown QDs deterministically integrated into mesas utilizing insitu lowtemperature electronbeam lithography combined with cathodoluminescence, for increased extraction efficiency. Comprehensive combined experimental (microphotoluminescence, photoluminescence excitation and correlation spectroscopy) and theoretical (8band k·p numerical calculations combined with configuration interaction method for excitonic states) study of band structure and optical properties, and in particular singlephoton generation will be presented. The influence of excitation energy as well as effect of temperature on the single photon emission purity has been studied and as a result triggered highpurity singlephoton emission has been realized under pshell resonant excitation. 
12:35  14:05  LUNCH BREAK 
Session: Single Photon DetectionChair: Ronald Walsworth  
14:05  14:35  Progress in single photon imaging from the UV to the mid infrared using superconducting nanowire detectors Varun Verma National Institute of Standards and Technology, Boulder, CO Singlephoton detectors are an integral part of experiments in quantum optics, and have applications in quantum computing, quantum communications, and the characterization of single photon sources. In particular, superconducting nanowire singlephoton detectors (SNSPDs) are excellent broadband detectors due to their fast recovery times, low jitter, and low dark count rates. Until recently however, the efficiency of SNSPDs in the telecommunications band was relatively poor in comparison to other detector technologies. The recent development of amorphous superconducting alloys such as WSi and MoSi has led to significant improvement in system detection efficiency (~90%) compared to the early NbNbased SNSPDs. Furthermore, device yield has improved from ~30% to 100%, enabling for the first time the fabrication of SNSPD arrays and lowresolution singlephoton cameras. I will discuss how these improvements in efficiency and device yield are enabling new applications such as imaging from the UV to the midinfrared, with potential applications in astronomy and deepspace optical communications. Finally, I will outline new approaches to building arrays of SNSPDs for imaging at the single photon level. 
14:35  14:55  Photon counting instrumentation optimized for metrology applications Ivan Prochazka, Josef Blazej Czech Technical University in Prague, Brehova 7, 11519 Prague 1, Czech Republic We are presenting the development and achievements of photon counting instrumentation for metrology applications. In listed measurements the photon counting approach was verified to provide ultimate precision and accuracy. Satellite Laser Ranging (SLR) is a technique in which a network of observing stations measures the round trip time of flight of ultrashort laser pulses to satellites equipped with retroreflectors. It is the most accurate technique to determine the distances in space with submillimeter precision and few millimeters accuracy. Laser time transfer enables to compare time scales on ground and in space by means of SLR type measurements. For metrology applications new photon counting detectors and epoch timing systems were developed. They do provide ultimate timing resolution and extreme detection delay stability. Solid state photon counting detectors on silicon having an active area diameter of 0.2mm are providing timing resolution better than 20ps, the epoch timing systems provide subpicosecond timing resolution, linearity and stability. An entire photon counting measurement chain exhibits unique longterm detection delay stability of the order of hundreds of femtoseconds. The detectors were qualified for space missions. Recently nine units are operational in space for laser time transfer three new missions are under preparation. 
14:55  15:15  Cryogenic integrated optics in lithium niobate Stephan Krapick^{1}, Jan Philipp Höpker^{1}, Varun Verma^{2}, Adriana Lita^{2}, Viktor Quiring^{1}, Harald Herrmann^{1}, Christine Silberhorn^{1}, Tim Bartley^{1} ^{1}Department of Physics, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany Cryogenic temperatures are required for many quantum technologies, in particular quantum dots for single photon sources [14], and highefficiency, low noise superconducting detectors [5]. Reconciling these operating conditions with photonic processing through integrated optics is an ongoing challenge. Of the many platforms for integrated optics, titanium indiffused waveguides in lithium niobite (Ti:LN) offer a range of advantages, including very high coupling efficiency and lowloss transmission of orthogonal polarisation modes, low power and high speed electrooptic control, and efficient secondorder nonlinear optical processing [6]. I will report on progress towards adapting these techniques at cryogenic temperatures. Specifically, I will report on a lowpower electrooptic switch which is fully functional at 0.8K, the operating temperature of a broad class of superconducting nanowire singlephoton detectors (SNSPDs). This is demonstrated through the use of such detectors with the switch in the same cryostat simultaneously. The ultimate goal is to integrate both components on a single chip; to that end, I will also report on progress towards integrating SNSPDs on our Ti:LN waveguides, specifically methods to increase absorption in a travellingwave configuration. [1] M. D. Eisaman, J. Fan, A. Migdall, and S. V. Polyakov, Rev Sci Instrum, 82(7):071101 (2011) [2] S. Buckley, K. Rivoire, and Jelena Vukovi, Rep. Prog. Phys., 75(12):126503 (2012) [3] P. Lodahl, S. Mahmoodian, and S. Stobbe, Rev. Mod. Phys. 87, 347 (2015) [4] P. Senellart, G. Solomon, and A. White Nature Nanotechnology, 12(11):1026, (2017) [5] F. Marsili et al., Nature Photonics 7, 210–214 (2013) [6] W. Sohler et al., Optics and Photonics News, 19(1), 2431 (2008) 
15:15  15:35  Toward the integration of photonic circuit with a single photon source and superconducting nanowire detectors Gourgues Ronan ronan@singlequantum.com Nowadays, superconducting nanowire single photon detectors (SNSPDs) are the most advanced single photon detectors from the visible to the infrared. This is because of their high detection efficiency, very low dark count rate, high count rate, and high time resolution^{1}. Furthermore, they are compatible with Si technology^{2} making them very suited for quantum photonic circuits. I will present an integrated photonic device that emits and detects single photons onchip. The detectors are fabricated from a NbTiN film which is deposited directly on an oxidized Si waver. On top, we sputter a SiN layer from which photonic structures such as waveguides and grating couplers are fabricated. To develop the fabrication process, we estimate the optical absorption of the SNSPD by performing 3D Finite Differential Time Domain simulations. We show the feasibility of our approach by presenting optical and electrical measurements. Our operational photonic chip lays the basis for a future antibunching measurement. 1 Iman Esmael Zadeh and al ‘Singlephoton detectors combining near unity efficiency, ultrahigh detectionrates and ultrahigh time resolution’, APL Photonics (2017). 2 Carsten Schuck and al, ‘Waveguide integrated low noise NbTiN nanowire singlephoton detectors with milliHz dark count rate’, Scientific Reports 3, Article number: 1893 (2013). 
15:35  15:45  STUDENT AWARD PRESENTATION 
15:45   END OF SYMPOSIUM 
Heisenbergscaling measurement of the singlephoton Kerr nonlinearity using mixed states Geng Chen^{1,2}, Nati Aharon^{3}, YongNan Sun^{1,2}, ZiHuai Zhang^{1,2}, WenHao Zhang^{1,2}, DeYong He^{1,2}, JianShun Tang^{1,2}, Yaron Kedem^{4}, ChuanFeng Li^{1,2}, GuangCan Guo^{1,2} ^{1}CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, 230026, China Improving the precision of measurements is a significant scientific challenge. Previous works suggest that in a photoncoupling scenario the quantum fisher information shows a quantumenhanced scaling of N^{2}, which in theory allows a betterthanclassical scaling in practical measurements. In this work, utilizing mixed states with a large uncertainty and a postselection of an additional pure system, we present a scheme to extract this amount of quantum fisher information and experimentally attain a practical Heisenberg scaling [1]. We performed a Heisenberg limited measurement of the Kerr nonlinearity of a single photon, where an ultrasmall Kerr phase of 6 *10^{8} was observed with an unprecedented precision of 3.6*10^{10}. Moreover, by using an imaginary weakvalue the scheme is robust to noise originating from the selfphase modulation. [1] Geng Chen, Nati Aharon, YongNan Sun, ZiHuai Zhang, WenHao Zhang, DeYong He, JianShun Tang, XiaoYe Xu, Yaron Kedem, ChuanFeng Li, and GuangCan Guo, Nat. Commun. 9, 93 (2018). 
Monolithic Quantum Light Source with Hybrid Pumping David Fuster, Luisa González, Yolanda González, Benito Alén IMNCNM, Insituto de Micro y NanoTecnología, CSIC. Tres Cantos, Spain Back in 2002, Toshiba released its pioneer Quantum LED design. [1] It opened a route for electrically driven quantum light sources adapted to different spectral ranges and environments. However, several constraints of the design, like the lack of a builtin wavelength tuning mechanism, or how to surpass the large sheet resistance in nanophotonic structures, remained unsolved. Just recently, completely new approaches appeared adding new functionalities to the original design. [2,4] We will present our own design. It is based on a vertical multijunction heterostructure where quantum light emission and tuning into photonic crystal cavities might become possible, for the first time, without constraints. [2] The device comprises of two separated electrical injection and electrical tuning regions in a bipolar transistor configuration. The connection between them is purely optical and thus, it naturally avoids the sheet resistance problems that plague other approximations, especially when applied to nanophotonic devices. The first fabricated devices show single photon emission with g2(0)<0.1 at injection currents as low as 100 mA/cm2 and fully linear conversion between electrical power and single photon flux. [1]Z.Yuan et al Electrically Driven SinglePhoton Source. Science 2002, 295, 102. [2]B. Alén et al “Tunable monolithic quantum light source and quantum circuit thereof” Patent pending EP/17382061.4, PCT/EP2018/052960. Date: Feb 8th 2017 [3]J. P.Murray et al “Electrically Driven and Electrically Tunable Quantum Light Sources”. Appl. Phys. Lett. 2017, 110 (7), 071102. [4]P.Munnelly et al “Electrically Tunable SinglePhoton Source Triggered by a Monolithically Integrated Quantum Dot Microlaser”. ACS Photonics 2017, 4 (4), 790–794. 
Offresonant effects in a cavityassisted nonlinear generation of photon pairs Valentin Averchenko, Gerhard Schunk, Michael Foertsch, Martin Fischer, Dmitry Strekalov, Gerd Leuchs, Christoph Marquardt MaxPlanckInstitut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen Cavityassisted spontaneous parametric downconversion (SPDC) and spontaneous fourwave mixing (SFWM) in nonlinear optical materials are practical methods to generate narrowband timeenergy entangled photon pairs, which are required for a number of quantum information protocols. Here, we study the generation of the photon pairs for the general case of offresonant conversion, namely, when the frequencies of the generated photons can possess a mismatch from the cavity resonances. Such frequency mismatch is temperature dependent and requires an additional control in an experiment. We propose a generic model to describe a cavityassisted SPDC and SFWM. We show that the mismatch reduces the generation rate of the photons, distorts the spectrum and the autocorrelation function of the generated fields, and affects the photon generation dynamics. We verify results experimentally using parametric generation of the photon pairs in a nonlinear whispering gallery mode resonator (WGMR) as a platform with controlled frequency mismatch. Our results reveal the role of the frequency mismatch on the photons generation process and importance to control it. Results also constitute a step to full control over the spectrotemporal properties of narrowband entangled photon pairs and will be useful for heralded generation of narrowband singlephoton pulses with the tailored temporal shape. 
Integrated Photonic Platforms for Efficient Collection of Single Photons from SolidState Quantum Emitters F. Böhm^{1}, N. Nikolay^{1}, C. Pyrlik^{2}, J. Schlegel^{2}, A. Thies^{2}, B. Lubotzki^{3}, A. Dohms^{1}, H. Abudayyeh^{3}, N. Sadzak^{1}, B. Sontheimer^{1}, A. Wicht^{2}, R. Rapaport^{3}, O. Benson^{1} ^{1}AG Nanooptik, HumboldtUniversität zu Berlin, Germany Efficient single photon sources effectively coupled to a single optical mode pose a crucial building block for future applications in quantum information science [1]. So far quantum optics experiments with single photon emitters, e.g. nitrogenvacancy (NV) centers in diamond are limited to large experimental setups with sophisticated detection systems including high NA objectives and precisely aligned freespace optics. We report on two different approaches aiming at integrating nanosized quantum emitters to photonic structures in order to enhance and facilitate the collection of their emission into a single optical mode. One approach is the evanescent coupling of a single NV center to waveguide structures fabricated from ultrapure silica exhibiting exceptionally low intrinsic fluorescence [2]. We will present results regarding the excitation of single quantum emitters and the detection of single photons via these novel monolithic photonic structures. Another approach is the coupling of single NV emitters to hybrid dielectric/metallic bullseye antennas [3]. These integrated devices allow the collection of a large amount of the NV centers emission and redirection of this emission with a high directionality. We will present results on the precharacterization and functionalization of these hybrid antennas. [1] Aharonovich, I., Englund, D., & Toth, M., Nature Photonics, 10.10 (2016): 631. [2] Henze, R., Pyrlik, C., Thies, A., Ward, J. M., Wicht, A., & Benson, O., Applied Physics Letters 102.4 (2013): 041104. [3] Abudayyeh, H. A., & Rapaport, R., Quantum Science and Technology 2.3 (2017): 034004. 
Integrated MicroresonatorStabilized Light Source for (Quantum)metrology 
Quantum electrodynamics in the transition between waveguide and nanocavity Emil V. Denning^{1}, Andreas D. Østerkryger^{1}, Jake IlesSmith^{1,2}, Niels Gregersen^{1}, Jesper Mørk^{1} ^{1}Department of Photonics Engineering, DTU Fotonik, Technical University of Denmark, Building 343, 2800 Kongens Lyngby, Denmark Quantum dots in photonic nanocavities play an important role in quantum optics and optical quantum information technologies, both as single photon sources and more generally as lightmatter interfaces. Such nanocavities are often based on a waveguidelike dielectric structure with longitudinal translation invariance and confining the light in the transverse direction. The translation invariance is then broken by adding a pair of mirrors in order to form a cavity, the optical properties of which depend on the mirror reflectivity as well as the underlying waveguide structure [1].
[1] N. Gregersen et al., Optics Express 24, 20904 (2016). [2] G. Lecamp et al., Physical Review Letters 99, 023902 (2007). [3] J. IlesSmith et al., Nature Photonics 11, 521 (2017). 
Design and Fabrication of Versatile Optical Cavities for Quantum Networks Thomas H Doherty, Marwan Mohammed, Naomi Holland, Klara Theophilo, Dustin Stuart, Axel Kuhn University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK A scalable quantum network will require an effective interface between light and matter. A high finesse optical resonator, which strongly couples a single atom to a photon, forms a key element. The application of these systems has been demonstrated in multiple studies [1,2], including as scalable source of bespoke single photons. However, the techniques used to fabricate optical cavities have remained largely unchanged since their introduction. A variety of engineering challenges have prevented the production of highly curved, perfectly reflecting, mirrors. This has resulted in insufficient access to persistently trap an emitter in a cavity, weak atomic coupling and perturbing polarization dependent effects. However, with the continual development of modern manufacturing processes, such as laser ablation [3] and focussed ion beam milling [4], these challenges can now be overcome. A new generation of resonators are being constructed with stronger atomic coupling, a reduction to birefringence and greater access to the cavity mode. We review the stateoftheart in the techniques which make this possible, the potential applications of these resonators and their position in a future quantum network. [1] Kuhn, A. Engineering the AtomPhoton Interaction, Chapter 1, Springer International PU (2016). [2] Reiserer, A. & Rempe, G., Reviews of Modern Physics, 87, 13791418 (2015). [3] Hunger, D. et al., New Journal of Physics 12, 065038 (2010). [4] Dolan, P. et al., Optics Letters 35, 3556 (2010). 
Optical Antennas for Color Centers in Diamond Philipp Fuchs^{1}, Thomas Jung^{1}, Hossam Galal^{2}, Mario Agio^{2}, XiaoLiu Chi^{3}, Stephan Götzinger^{3}, Christoph Becher^{1} ^{1}Universität des Saarlandes, Fakultät NT  FR Physik, Campus E2.6, 66123 Saarbrücken Color centers in diamond, e.g. the nitrogen (NV), silicon (SiV) or germanium (GeV) vacancy centers, have become very promising candidates for the implementation of stationary qubits or bright single photon sources. One of the most challenging problems when working with these defects is the low collection efficiency of photoluminescence photons out of unstructured diamond films. Because of total internal reflection at the diamondairinterface, this problem cannot be solved simply by using high NA objectives and the collection efficiency is usually limited to a few percent. Here, we present some new approaches to increase the collection efficiency by precisely controlling the color centers' dielectric environment. 
Analysis of nanoantennas for enhancement of entangled twophoton Andrzej Gajewski, Karolina Slowik Nicolaus Copernicus University, Faculty of Physics, Astronomy and Informatics, ul. Grudziadzka 5, Torun 87  100, Poland We present the result of broad analysis of the possibility of using nanoantennas  both dielectric and metallic  in order to enhance twophoton emission rate from a quantum dot in a realistic scenario. Quantum dots are a very promising source of nonclassical light with a wide variety of possible application and a strong candidate for elements of Integrated photonic quantum circuits. One way of controlling properties of emitted photons is by the use of nanoantennas. Nanoantennas are nanoscaled optical devices, usually made of noble metals or dielectric. In analogy to their macroscopic counterparts, nanoantennas can mediate between propagating radiation and localized electromagnetic fields. With their nanoscopic size, they sustain resonant response within the optical or nearinfrared range. Nanoantennas are commonly used as a way to enhance emission or redirect it. We show a result of the study of the geometry of nanoantennas which could in practice lead to enhancement of twophoton entangled emission from a single quantum dot. 
Single photon emission of ZnO nanocrystals: New progress 
Timeresolved analysis of the NV centers' fluorescence dynamics 
Quantum Theory of 1/f Frequency Fluctuations Part 1 DeCoherence as the Cause of Fundamental 1/f Noise  Peter H Handel^{1}, Erika Splett^{2} ^{1}Univ. of MissouriSt. Louis, 28 Roclare Ln, Saint Louis MO 63131, USA The Conventional Quantum 1/f Effect is present in any scattering cross section and process rate involving charged particles or current carriers. The present paper shows how bremsstrahlung and decoherence at all frequencies yield probability density fluctuations at all frequencies in the outgoing scattered beam, that are observed as fundamental baseband 1/f noise and as 1/f frequency fluctuations, or phase noise close to carrier, in materials, devices and systems. We emphasize quantum decoherence showing that the fundamental, universal 1/f noise is both a phenomenon of decoherence and of infrared divergence in quantum electrodynamics. On this basis we give the first simple, universal, engineering formulas, applicable for the ultralow 1/f noise optimization of all HiTech applications, of the materials, devices and systems of modern industry, microelectronics, nanotechnology, highest stability resonators, oscillators and clocks, MEMS, and any resonant and nonresonant sensors. Quantum 1/f noise, i.e, the coherent and conventional Q1/f Effects is a new fundamental aspect of quantum physics. P.H. Handel and A.G. Tournier, “Nanoscale Engineering for Reducing Phase Noise in Electronic Devices,” invited paper, Proc. IEEE 93, 17841814 (2005). 
Quantum 1/f Optimization of Resonant & Nonresonant Sensors  THE EXAMPLE OF QUANTUM WELL INFRARED DETECTORS Peter H Handel, Amanda Truong Dept. of Physics and Astronomy, University of Missouri, Saint Louis Mo 63121, USA The Quantum Well Infrared Photodetector (QWIP) is a multiple quantum well (MQW) semiconductor photon detector. The design allows a thermally activated carrier within the well to escape, joining others in the dark current. This dark current is present even without illumination or background radiation. Quantum 1/f (Q1/f) fluctuations of this dark current compete with the signal to be detected, and limit the detectivity. The noise is described by the universal formulas of the fundamental conventional Q1/f effect, from decoherence. They describe the fluctuations of physical cross sections of processes that limit the dark current, such as scattering of the electrons, tunneling, or trapping. We calculated the conventional Q1/f noise for 4 samples described and measured in papers by Jiang, Jelen and Thibaudeau. At 1 A dark current, we calculated an r.m.s. Q1/f noise current of 10E11, 5x10E11, 2x10E13 and 2xE10 A/(Hz)^{1/2} for Jiang, Jelen sample A, Jelen sample B and Thibaudeau respectively. The plots of theoretical Q1/f noise currents versus dark current fit the experiment well. 
Acoustic charge and electronspin transport in GaAs quantumwires Paul L. J. Helgers^{1,2}, Klaus Biermann^{1}, Haruki Sanada^{2}, Yoji Kunihashi^{2}, Paulo V. Santos^{1} ^{1}PaulDrudeInstitut Berlin, Germany We investigate a concept for acoustically driven singlephotonsources, based on planar GaAs quantum wires (QWRs) [1] embedded in optical microcavities. The QWR forms at sidewalls of patterned mesas on (Al,Ga)As templates, due to anisotropic MBE overgrowth of a 10nm quantum well structure [2,3]. Spinpolarized carriers are optically injected in the QWR and acoustically transported to an embedded recombination center to emit single photons. We observe charge transport over tens of microns and measured nanosecond timescale spin relaxation times in these QWRs. The latter are increased due to surface acoustic waves, promising spin transport lengths of tens of microns. We measure lineedgeroughness of the pattern edge up to 20 nm, complicating acoustic transport for narrow QWRs. Lineedgeroughness is mainly caused by photolithography. Using scanning transmission electron microcopy, we evaluate the thickness (26 nm) and width (200 nm) of the QWRs. We will evaluate the potential of these structures as efficient acoustically driven singlephotonsources. This project has received funding from the European Union's Horizon program under grant agreement No 642688. [1] O. D. D. Couto, Jr, S.Lazic, F. Iikawa, J.A. H. Stotz, U. Jahn, R. Hey, P. V. Santos; Nature Photonics 3 (2009) [2] R. Nötzel, J. Menninger, M. Ramsteiner, A. Ruiz, H. Schönherr, K. Ploog; Applied Physics Letters 68 (1996) 
Effect of temperature on emission from deterministic quantum dotmesas in the 1.3 µm range P. Holewa^{1}, A. Musiał^{1}, P. Mrowiński^{1}, K. Gawarecki^{2}, J. Misiewicz^{1}, N. Srocka^{3}, D. Quandt^{3}, A. Strittmatter^{3,4}, S. Rodt^{3}, S. Reitzenstein^{3}, G. Sęk^{1} ^{1}Laboratory for Optical Spectroscopy of Nanostructures, Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50370 Wrocław, Poland Here we report on temperaturedependent photoluminescence (PL) studies and singlephoton emission purity of MOCVDgrown In_{0.75}Ga_{0.25}As/In_{0.2}Ga_{0.8}As/GaAs quantum dots (QDs) emitting at 1.3 μm [12]. In order to enhance the extraction efficiency and spatial isolation of QDs, deterministic mesas were fabricated over individual preselected QDs using lowtemperature insitu electronbeam lithography [3]. Emission from single QDs was observed up till 80 K. The activation energies for the PL quenching process neither differ much between various excitonic complexes, nor depend on the ground state energy. They are in the range of (1020) meV which indicates that the main quenching mechanism is the escape of holes to higher states supported by the electronic structure calculations within 8 band kp model. For the positively charged trion (X^{+}) a pronounced intensity increase is observed in the range of (1030) K. Corresponding process has an activation energy of 1.9 meV characteristic also for X^{} PL intensity reduction indicating thermal activation of positive carrier traps in the QD vicinity [4]. Highpurity singlephoton emission from X^{+} complex was measured up to at least 30 K, which is important step towards lowcost quantumdotbased single photon sources at telecom, employing cryogenicfree Stirling cooling [5]. [1] F. Guffarth, R. Heitz, A. Schliwa, O. Stier, N. N. Ledentsov, A. R. Kovsh, V. M. Ustinov, and D. Bimberg, Phys. Rev. B 64, 085305 (2001). [2] Ł. Dusanowski, P. Holewa, A. Maryński, A. Musiał, T. Heuser, N. Srocka, D. Quandt, A. Strittmatter, S. Rodt, J. Misiewicz, S. Reitzenstein, and G. Sęk, Opt. Express 25, 31122 (2017). [3] M. Gschrey, A. Thoma, P. Schnauber, M. Seifried, R. Schmidt, B. Wohlfeil, L. Krüger, J.H. Schulze, T. Heindel, S. Burger, F. Schmidt, A. Strittmatter, S. Rodt, and S. Reitzenstein, Nature Commun. 6, 7662 (2015). [4] F. Olbrich, J. Kettler, M. Bayerbach, M. Paul, J. Höschele, S. L. Portalupi, M. Jetter, and P. Michler, J. Appl. Phys. 121, 18 (2017). [5] A. Schlehahn, L. Krüger, M. Gschrey, J.H. Schulze, S. Rodt, A. Strittmatter, T. Heindel, and S. Reitzenstein, Rev. Sci. Instrum. 86, 1 (2015) 
Practical singlephoton detectors made of micronwide superconducting strip Alexander Korneev, Eugeniy Smirnov, Yuliya Korneeva, Irina Florya, Nadezhda Manova, Alexander Semenov, Gregory Goltsman, Teunis M. Klapwijk akorneev@rplab.ru Superconducting singlephoton detectors (SSPD) [1] are used in many applications of quantum optics. In the currently standard embodiment the detector is a 100nmwide and severalnmthick superconducting strip, with an areafilling topology to enable efficient optical coupling. Recently, we have demonstrated that singlephoton detection can be observed in much shorter, micronwide strips, which carry a high critical current density close to the critical pairbreaking current [2]. The new insight and the new layout leads to singlephoton detection with a much higher counting rate, due to the reduction in total kinetic inductance. device topology. We will present performance characterization of practical detectors of sufficiently large area suitable for coupling to singlemode optical fibres. [1] Natarajan, C. M., et al Supercond. Science and Technology, 25(6), 063001, 2012. [2] arXiv:1802.02881 [condmat.suprcon] 
Optimizing SPDC photon pairs for quantum communication applications Mikolaj Lasota, Karolina Sedziak, Piotr Kolenderski Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziadzka 5, 87100 Torun, Poland One of the most important problems of fiberbased long distance quantum communication (QC) is the temporal broadening of singlephoton wavepackets, resulting from the propagation of those photons through dispersive media. Due to this effect the detection windows for such signals have to be made sufficiently long, increasing the amount of noise registered by the singlephoton detectors and lowering the performance of QC protocols. However, the temporal wavepackets of photons emitted by means of spontaneous parametric downconversion (SPDC) process highly depend on the properties of a utilized pump laser and nonlinear crystal. Here we investigate the problem of optimizing a SPDC source for its use in a given quantum communication scheme. In particular, we derive analytical formula for optimal pump laser settings for a given nonlinear crystal. We also design an optimal SPDC source for a QC application assuming that one can freely choose both the properties of the pump laser and the crystal. Finally, we apply the obtained results to the security analysis of symmetric and asymmetric quantum key distribution schemes. We show that by optimizing the SPDC source according to our guidelines one can extend the maximal security distance of a nonoptimized scheme by several tens of kilometers. 
High efficient setup for filtering the singlephoton spectral emission of InGaAs quantum dots José Luis Velázquez, Helmuth Hofer, Beatrice Rodiek, Sefan Kück, Alicia Pons, Joaquín Campos and Marco López1,* PhysikalischTechnische Bundesanstalt, Bundesallee 100, D38116, Braunschweig, Germany / Instituto de Óptica, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain The purity of singlephoton sources often suffers from multiple emission lines in the emission spectrum of quantum dots based semiconductor systems. Spectral filtering, which selects only one emitting center, leads to a significant decrease in the transmitted photon flux. Here, we present the optical characterization of a compact and efficient setup for filtering the singlephoton emission of an InGaAs quantum dot. The setup consists of two bandpass optical filters placed one after the other. Through a precise rotation of the filters, the convolution of their transmission windows allows to reach a spectral filtering with a full width at half maximum (FWHM) of less than 0.1 nm and a transmission of approx. 90 % in the wavelength range from 920 nm to 930 nm. These results are promising towards the development of a compact and high efficient singlephoton source based on such quantum dots. Such sources can be used, especially, in the quantum radiometry, where a high photon flux rate is required for the efficiency calibration of singlephoton detectors. Furthermore, the experimental results obtained when using this setup for filtering the singlephoton emission of a stateoftheart InGaAs quantum dot with embedded microlens will also be presented at this conference. 
Measuring dispersion in nonlinear crystals beyond detectors’ spectral range Marta Misiaszek, Andrzej Gajewski, Piotr Kolenderski Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87100 Torun, Poland We show a technique for dispersion measurements in a nonlinear crystals by making use of phase matching in the process of parametric down conversion. The method can be applied for various types of crystals. It allows to determine the coefficients of Sellmeier equations with limited detection capabilities. Here we present the method based on an exemplary PPKTP crystal phasematched for 396 nm to 532 nm and 1550 nm, which can be tuned with temperature and pump wavelength. Using only one spectrometer for the UVvisible range, we show a procedure to determine the dispersion in the IR range. 
A fibretip FabryPérot cavity for deterministic, strong atomphoton interactions Marwan Mohammed, Thomas Doherty, Naomi Holland, Klara Theophilo, Dustin Stuart, Axel Kuhn University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK Optical fibretip FabryPérot cavities [1] can be used for strong coupling of an atom's electronic state and the cavity's photon state, allowing for a reversible and controllable quantum interface. Besides the benefit of coupling the light directly to the fibre, the small fibretip diameter allows for optical access with numerical apertures as strong as 0.6, making possible the use of tightly focused dipole traps that hold single atoms at cavity standingwave antinodes [2]. Our symmetric confocal fibre cavity is formed of two singlemode fibres, with a finesse of 100,000 and a predicted cooperativity of 29. Whilst there are constraints on the modematching efficiency and mirror parameters of these cavity types, we are developing novel designs and mirror ablation techniques that will overcome these. The deterministic nature and strength of the atomphoton interaction will be particularly useful for photonic quantum networks. [1] D. Hunger et al., New J. Phys. 12, 065038 (2010). [2] C. Muldoon et al., New J. Phys. 14 073051 (2012) 
Towards Energy Transferbased Sensing and Imaging using Color Centers in SingleCrystal Diamond Richard Nelz, Michel Challier, Ettore Bernardi, Elke Neu Universität des Saarlandes, Fakultät NT  Fachrichtung Physik, Campus E2.6, 66123 Saarbrücken Individual nitrogen vacancy (NV) color centers in diamond are bright, photostable dipole emitters [1] and consequently optimal candidates for novel scanning near field microscopy techniques [2]. Here, NV centers form one member of a Förster Resonance Energy Transfer (FRET) pair. Due to their broadband emission (> 100 nm), NVs are versatile donors for FRET to systems absorbing in the near infrared spectral range. Promising applications include, e.g., nanoscale imaging of fluorescent molecules or nanomaterials like graphene [2]. Critical parameters for FRET are the NV’s quantum efficiency, charge state stability and NVsampledistance. Previous experiments performed nanodiamondbased FRET [2], however NVs in this material might suffer from quenching, instability and bad control of surface termination. We here present first results towards FRET using color centers in single crystal diamond (SCD) via demonstrating quenching of NVs in SCD when applying graphene to the surface. While the FRET effect is present, the NVs retain their magnetic sensing capabilities. To precisely control the NVsampledistance, we aim to use shallowly implanted NVs in optimized cylindrical nanostructures as scanning probes in our homebuilt combination of confocal and atomic force microscope. [1] Bernardi et al., Crystals, 7, 124 (2017). [2] Tisler et al., Nano Lett., 13, 31523156 (2013). 
TimeFrequency QKD over FreeSpace and Fiber Channels Jasper Rödiger^{1,2}, Nicolas Perlot^{1}, Ronald Freund^{1}, Oliver Benson^{2} ^{1}Fraunhofer Heinrich Hertz Institute (HHI), Einsteinufer 37, 10587 Berlin, Germany We provide performance results on a QKD scheme based on the timefrequency uncertainty relation, referred to as timefrequency (TF‑) QKD. It is a BB84like QKD protocol with the two bases being realized by modulations in time and frequency, namely pulse position modulation (PPM) and frequency shift keying (FSK), where the energytime uncertainty relation ensures security. TFQKD can be implemented mostly with standard telecom components in the 1550 nm band and is well suited for freespace and fiber communication. In TFQKD, polarization is not used, thus can be used for duplexing. With PPM and FSK, it is possible to use an arbitrarily large alphabet and thus to transmit multiple bits per photon. This is especially beneficial when many photons reach and saturate the detector, or when there are other limits on the photon rate, e.g. an upper limit on the gating frequency for detectors, which are operated in gating mode (e.g. InGaAs avalanche photondiodes). We have implemented the TFQKD protocol [1] and performed transmissions over freespace and fiber channels, have performed numerical simulations regarding pulse forms and number of symbols per basis [2] and performed an experiment using four symbols in each basis as a first step toward large alphabets. [1] M. Leifgen, R. Elschner, N. Perlot, C. Weinert, C. Schubert, and O. Benson, Phys. Rev. A, vol. 92, no. 4, p. 042311, 2015. [2] J. Rödiger, N. Perlot, R. Mottola, R. Elschner, C.M. Weinert, O. Benson, and R. Freund, Phys. Rev. A, vol. 95, p. 052312, May 2017. 
Second order correlation measurements of quantum emitters in hexagonal boron nitride and their implications on the underlying level system Bernd Sontheimer^{1}, Mehran Kianinia^{2}, Carlo Bradac^{2}, Merle Braun^{1}, Igor Aharonovich^{2}, Milos Toth^{2}, Oliver Benson^{1} ^{1}AG Nanooptik, Institut für Phsysik, Humboldt Universität zu Berlin, Newtonstrasse 15, 12489, Germany Single photon sources (SPSs) are prime candidates for a myriad of applications in integrated quantum optics and information processing. Local quantum emitters in hexagonal boron nitride (hBN), a widebandgap twodimensional material, have recently emerged as promising SPSs. While the origin and atomic structure of these emitters are still under debate, they can exhibit remarkable properties including the ability of subbandgap excitation at room temperature, high brightness and short excited state lifetime.[1] To fully understand the origin of these characteristics and harness or even engineer them in the future, the underlying electronic level structure has to be revealed. Up to now, efforts based on density functional theory are not fully conclusive. Here, we present our experimental approach using statistical analysis of the single photon stream of a SPS to gain insights into the emitters nature. By means of a twolaser repumping scheme we identify a class of hBN quantum emitters with a fastdecaying intermediate and a longlived metastable state accessible from the first excited electronic state. Based on those findings we propose a level scheme that matches our observations. To demonstrate the utility of the unique photophysics of these quantum emitters, we realize a new modality of farfield superresolution imaging.[2] [1] B. Sontheimer, et al., Phys. Rev. B 96, 121202(R) (2017) [2] M. Kianinia, et al., arXiv:1709.08683 (2017) (accepted to Nat. Commun.) 
Quantum Theory of 1/f Frequency Fluctuations Part 2: Quantum 1/f Optimization ofQuartz Resonators, Electronics, MEMS, Clocks, Piezotransducers, and Resonant Sensors Peter H. Handel^{1}, Erika Splett^{2} ^{1}Univ. of MissouriSt. Louis, 28 Roclare Ln, Saint Louis, MO 63131, USA The present poster gives examples of Quantum 1/f (Q1/f) optimization of sensors and systems. It investigates the application of the quantum theory of 1/f noise to the optimization of quartz and Si MEMS sensors for ultralow 1/f noise and phase noise close to carrier. This multidisciplinary poster is transformative, because it allows orders of magnitude increases of sensitivity, detectivity, and stability, based on this new fundamental aspect of quantum mechanics we have discovered. It provides simple engineering formulas that allowed us to give optimization rules for both resonant and nonresonant sensors. This includes quartz microbalances, biochemical sensors based on BAW and SAW resonators of quartz or other piezoelectric materials, MEMS/NEMS resonant and nonresonant sensors, FET and HFETbased detectors, MQW and QWIPs photodetectors, infrared junction and MIS detectors, quantum dot detectors, etc, all HiTech. Due to the novelty of the field, we focus here both on the basics and on practical examples of optimization. T.F. George and P.H. Handel: “Quantum 1/f Effect Based on Quantum Information Theory”, Internatl. J. of Modern Physics B, World Scientific Publishing Co. Vol. 20, Nos. 1113, pp 13431362 (2006). 
Quantum dotmicrolenses for singlephoton sources operating at telecom wavelength N. Srocka^{1}, P. Mrowinski^{2}, Ł. Duanowski^{2,3}, A. Musiał^{2}, G. Sęk^{2}, D. Quandt^{1}, A. Strittmatter^{1,4}, S. Rodt^{1}, S. Reitzenstein^{1} ^{1}Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin, Germany Advanced quantum communication applications require singlephoton sources featuring i) high photonextraction efficiency, ii) high flux rate, iii) high suppression of multiphoton emission and iv) high degree of photon indistinguishability. The concept of monolithic microlenses aligned to selfassembled semiconductorquantumdots has been proven to be an efficient approach to satisfy all of these four requirements in a single device operating at 900 to 950 nm [1]. [1] M. Gschrey et al., Nat. Commun. 6, 7662 (2015). 
Nanostructural beam splitter 
Single photon generation using nanofiber cavityQED systems Yuuki Tokunaga^{1}, Hayato Goto^{2}, Shota Mizukami^{3}, Takao Aoki^{3} ^{1}NTT Secure Platform Laboratories, NTT Corporation, Musashino 1808585, Japan Nanofiber cavityQED systems are promising candidates for quantum information processing because of the fiberbased transmission capability and the efficient coupling of an atom and light thanks to the tight transversalmode confinement and the large evanescent fields of a nanofiber. Especially, the small mode area of the nanofiber cavityQED systems greatly contributes to achieve the strong coupling region [1] even with the current large cavity internal losses compared to the freespace system. We show that the success probabilities of cavityQEDbased single photon generation using the stimulated Raman adiabatic passage or the Purcell effect are both upper bounded by a single dimensionless quantity ``internal cooperativity,""" which is introduced here as the singleatom cooperativity parameter with respect to the cavity internal loss rate, instead of the cavity total loss rate. This is the consequence of the tradeoff with respect to the cavity internal loss and atomic spontaneous emission. The upper bound is achieved by optimizing cavity external loss rate, which is possible by designing or tuning the transmittance of the output coupler. This result indicates that the nanofiber cavityQED systems have a great potential to generate single photons with high probability by reducing the current cavity internal losses. [1] S. Kato and T. Aoki, Phys. Rev. Lett. 115, 093603 (2015). 
Is the photon a soliton? Imants Bersons^{1}, Rita Veilande^{1}, Ojars Balcers^{2} ^{1}Institute of Atomic Physics and Spectroscopy, University of Latvia A plane wave solution of the Maxwell equations describes all optical phenomenon. But the plane wave is exposed to diffraction and when it spreads in a space it has to disappear, therefore, it cannot describe a photon. The quantization procedure provides the correct energy and the creation and annihilation probabilities of photons, but the diffraction of photons is suppressed by the artificial quantization box. Our viewpoint is that the photon can be described only by a nonlinear equation with a soliton type solution. We assume that light induces the polarization and magnetization of a vacuum only along the direction of its propagation. Based on the Maxwell equation we propose a nonlinear equation which is similar to the generalized nonlinear Schrödinger equation [1]. Its soliton type solution could outline a photon. The one and twosoliton solutions are found in a vacuum and in dielectrics [2, 3]. If the photon is a soliton, then when two photons collide, they have to shift in space like solitons do. Would it be observed? [1] I. Bersons, Latv. J. Phys. Tech. Sci. 50, 60 (2013). [2] I. Bersons, R. Veilande and A. Pirktinsh, Phys. Scr. 89, 045102 (2014). [3] I. Bersons, R. Veilande ande O. Balcers, Phys. Scr. 91, 065201 (2016). 
Applications of timecorrelated singlephoton counting cameras Ryan Warburton, Richard Walker, Jakub Nedbal Photon Force, Alrick Building, Edinburgh, EH9 3BF, Scotland Singlephoton avalanche diode (SPAD) detectors have been the cornerstone of photon counting and timing applications for many years. Whilst singlepoint detection has uses in many quantum applications, there are many areas that would benefit from singlephoton detection and timing with the ability to form an image simultaneously. Our PF32 camera combines 1024 SPADs in a 32x32 array, each with its own timing capabilities to precisely tag the arrival of a photon to an accuracy of 55 ps. In terms of quantum measurements, this opens up new possibilities: measuring the fullfield of the downconverted photons in an entangled system, for example. Miniaturisation is another key challenge of developing usable quantum systems: normal TCSPC systems can be bulky, whereas using CMOS processing, these 1024 SPADs and all the necessary electronics can be contained within a package about the same size as a digital camera and addressed through a USB3 cable. This also helps with the integration of such detectors into larger systems where power requirements and realestate are key considerations. We will present the latest work undertaken with the PF32 camera, and demonstrate how it can help with the progress of quantum science. 
Effects of photon losses on the accessible quantum Fisher information obtained by photon number resolving detectors Junyi Wu, Holger F. Hofmann Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 131, Higashi Hiroshima 7398530, Japan In quantum metrology, the optimum quantum fisher information (FI) of a quadrature component of light field can be obtained in photon number measurements implemented by perfect photon number resolving (PNR) detectors. However due to photon losses in PNR detectors, the FI obtained in real PNR measurements drops off. In this presentation, the effects of photon losses $eta$ in PNR detectors on quantum FI is studied. We derive an upper bound $I(eta)$ on the FI obtained in the PNR measurement under photon losses $eta$ and show that $I_{mathrm{F}}$ decreases monotonically with respect to $eta$. It is found that the FI obtained from displacedsqueezed states $I_{epsilon}$ drops faster than the one obtained from coherent states $I_{0}$, and upon a critical photon losses $eta_{c}$, it holds that $I_{epsilon} 
Atoms dressed by a multimode field Ben Yuen University of Oxford, Department of Physics The dressed atom picture [1,2] has proved highly successful at describing light matter interactions in an intuitive way, and accounts for the dynamics of both atom and field. We generalise this approach to describe the interaction of atoms and a field comprising of multiple frequency components. The natural extension of the single mode dressed atom picture gives rise to singularities when the system is expanded perturbatively, or erroneous level shifts and resonances when diagonalised numerically due to degeneracies in the dressed state energies. We find a nondegenerate basis for multimode dressed atoms which allows us to calculate the eigenstates and time evolution of the system. Our method gives a new perspective on nonlinear optical processes and produces accurate analytic approximations for the time evolution of an atom driven by a multimode field. [1] Shirley, J. H. (1965). Review, 138(4B), B979. [2] CohenTannoudji C and Haroche S 1969 Journal de Physique 30 153–168 
Generation and investigations of superthermal Light Steffen Zienert, Wolfgang Elsäßer Technische Universität Darmstadt, IAP  AG Halbleiteroptik, Schlossgartenstr. 7, 64289 Darmstadt The socalled pseudothermal light source or Martienssen lamp [1] based on a monochromatic laser beam and a rotating diffuser (ground glass) has proven its capability of emitting light with a second order correlation coefficient of two, thus photonbunched classical thermal light. This led to a fruitful number of quantum optics experiments, such as ghost imaging. Here, we extend this experimental scheme by adding a subsequent second rotating diffusor finally resulting in light with superthermal statistics, i.e. a second order correlation coefficient exceeding two [2]. For a comprehensive analysis of the second order correlation function we deployed a Hanbury Brown and Twiss (HBT) intensity interferometer based photoncounting setup consisting of two silicon based singlephoton avalanche diodes (SPADs) with a PicoHarp 300 timecorrelated single photon counting analysis system. We present experimental results of the second order correlation coefficient for various system parameters including spatial dependencies. [1] W. Martienssen and E. Spiller. American Journal of Physics, 32(12), 919–926 (1964) [2] Bin Bai, Jianbin Liu, Yu Zhou, Huaibin Zheng, Hui Chen, Songlin Zhang, Yuchen He, Fuli Li, and Zhuo Xu. Journal of the Optical Society of America B, 34(10), 2081–2088 (2017) 
The program consists of invited and contributed oral presentations, as well as a poster presentation according to the scheme below.
The detailed schedule will be published online mid/end of March 2018.
Wednesday, May 30 
Thursday, May 31 
Friday, June 1 


9:00  Invited  Invited  Invited 
9:30  Contributed  Contributed  Contributed 
9:50  Contributed  Contributed  Contributed 
10:10  Contributed  Contributed  Contributed 
10:30  Coffee Break  Coffee Break  Coffee Break 
11:00  Invited  Invited  Invited 
11:30  Contributed  Contributed  Contributed 
11:50  Contributed  Contributed  Contributed 
12:10  Contributed  Contributed  Contributed 
12:30  Lunch Break  Lunch Break  Lunch Break 
14:00  Invited  Invited  Invited 
14:30  Contributed  Contributed  Contributed 
14:50  Contributed  Contributed  Contributed 
15:10  Contributed  Contributed  Contributed 
15:30  Coffee Break  Coffee Break  Coffee Break 
16:00  Invited  Poster Session  
16:30  Contributed  
16:50  Contributed  
17:10  Contributed  
18:00  Reception 
We have received an overwhelming large amount of abstracts for talks and posters. We thank all particpants for their contribution.
The originally planned schedule did unfortunately not allow to accept all submitted abstracts for talks. We therefore included four "flash talk" sessions into the program. A flash talk offers with a maximum of 45 transparencies and 4 minutes a way to highlight a poster. There will also be no questions during the flash talks as there will be plenty of time for questioning and discussions at the poster session that follows the flash talks on the same day.
Symposium fees
The fee structure as well as terms and conditions for payment will be released at a later date.
Until February 5, 2018  February 6, 2018 until April 30, 2018  

Academic/University  300 €  350 € 
Industry and Private Sector  750 €  900 € 
Besides full symposium attendance, the fee includes all coffee breaks, a reception with free food and drinks, three lunches, and an abstract book. Attendees will be responsible for their own travel, lodging, and meals.
Please note the terms and conditions
 For payment you can choose between credit card (Visa, Master Card) and bank transfer. Possible bank charges have to be paid by the participant. Please note, that we do not accept checks.
 After online registration, you will receive an email notification including a PDF file that includes information on the payment procedure.
 In order to take advantage of the early bird rate (registration deadline: February 5, 2018), payments have to be received by February 19, 2018.
 All other payments have to be received within 14 days after date of registration.
 We will send an email confirming your participation once we have received your payment. If payment is overdue, your registration will not be processed and considered invalid.
 A receipt of payment will be included in our email confirmation of participation.
 Cancellation of registration must be submitted in writing or via email and is valid only with acknowledgment of receipt by PicoQuant GmbH. A refund of registration fees is dependent on the notice given:
 For cancellations made until April 30, 2018, 75 % of the received registration fee will be reimbursed. In case of cancellations after April 30, 2018, 25 % of the registration fee will be reimbursed.
 It is possible to name and send a substitute participant.
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Financial support
PicoQuant will grant a fee waiver to a few participants from the university and academic sector of economically less privileged countries. Accommodation, travel, and personal expenses still need to be paid by the participants themselves. The selection of sponsored people is completely the sole decision of PicoQuant and there is no right or guarantee to receive a fee waiver.
To apply for a fee waiver, please send us your application:
 a letter of application and
 a formal letter of recommendation from your department/institute
Deadline for a fee waiver application is February 5, 2018.
Please note that only one person per research group can be considered for a fee waiver.
Details on the fee waiver application process will be published at a later date.
The deadline to apply for a fee waiver has passed. We can no longer accept any fee waiver applications.
Registration
The registration will open soon.
The registration is closed. If you are still interested to participate, please contact us via email.
Registration opens in October 2017.
Symposium location
The workshop will be held in BerlinAdlershof. Details will be announced at a later date.
The symposium will be held in the "MaxBornSaal" in BerlinAdlershof, located in the southeast of Berlin.
MaxBornSaal
CarlScheeleStraße
12489 Berlin
Germany
Local area map showing the symposium location (red marker)
Accommodation
We have negotiated special rates for a limited number of rooms in several hotels/appartment block located close to the symposium location. The number of rooms as well as booking time are limited and we therefore advise to reserve your room as soon as possible.
City Tax
Please note that since the beginning of the year 2014, tourists staying overnight in Berlin are subject to paying an accommodation tax, the socalled City Tax. It amounts to five percent of the room rate (net price), excluding VAT and fees for amenities and services such as minibar, sauna, or spa area. The City Tax does only affect private overnight stays and NOT business travellers. The business purpose of a trip can be verified by a bill that is paid by or issued to the employer, or a letter from the company. If the accommodation is booked by the employer in the first place, there is no further proof necessary.
Also see the information at www.berlin.de
Airporthotel BerlinAdlershof
Rudower Chaussee 14, 12489 Berlin
Phone: +49307202222000
Fax: +49307202222100
Website of the hotel
reservierung@airporthotelberlinadlershof.de
 single room: 63 € (excl. breakfast)
 double room: 78 € (excl. breakfast)
 breakfast: 13 € per day and person
Booking code: QSYM PicoQuant.
Please use the booking form to reserve a room.
The rooms are bookable at this rate until May 16, 2018. We can not guarantee any reservations to these prices or any reservation at all after this date.
ADAPT Apartments
ErichThiloStraße 3, 12489 Berlin
Phone: +493067892980
Fax: +493067892982
Website of the apartment house
info@adaptberlin.de
 single room: 69 € (excl. breakfast)
 double room: 90 € (excl. breakfast)
Guests can join the breakfast in the bakeries or nearby hotels at the campus.
Wireless LAN is included in the room price.
Please book your room via email, using the booking code: QSYM PicoQuant.
The rooms are bookable at this rate until April 30, 2018 on a first come, first served basis. We cannot guarantee reservations at these prices or any reservations at all after this date.
Dorint Adlershof Berlin
Rudower Chaussee 15, 12489 Berlin
Phone: +4930678220
Fax: +4930678221000
Website of the Dorint Adlershof
info.berlinadlershof@dorint.com
 single room: 82 € (incl. breakfast)
Wireless LAN is included in the room price.
Booking code: QSYM PicoQuant.
Please contact the Dorint Adlershof Berlin via phone, fax, or email to book a room. If you do not wish to have breakfast included, please inform the hotel when making your reservation.
The rooms are bookable at this rate until April 30, 2018 on a first come, first served basis. We cannot guarantee reservations at these prices or any reservations at all after this date.
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