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Quantum Optics

Quantum Entanglement

A common quantum mechanical state of separated systems

Quantum entanglement is a physical phenomenon that occurs when quantum systems such as photons, electrons, atoms or molecules interact and then become separated, so that they subsequently share a common quantum mechanical state. Even when a pair of such entangled particles are far apart, they remain "connected" in the sense that a measurement on one of them instantly reveals the corresponding aspect of the quantum state of its twin partner. These "aspects" of quantum state can be position, momentum, spin, polarization, etc. While it can only be described as a superposition with indefinite value for the entangled pair, the measurement on one of the partners produces a definite value that instantly also determines the corresponding value of the other. The surprising "remote connection" between the partners and their instantaneous action "faster than light" that would seem to contradict relativity has been the reason for intense research efforts, both theoretically and experimentally. In the corresponding experiments, entanglement is proven by correlation of the measurment outcomes on the separated twins.

Scheme of a general set-up for entanglement measurementsEntangled quantum systems are typically analysed via coincidence correlation methods. For that purpose, the photons emitted by the systems are split using, e.g., a 50 / 50 beamsplitter or a polarization splitter and send onto two single photon sensitive detectors. The output of these detectors is then fed into a time tagging unit with high temporal resolution that allows not only to detect coincidences in a certain time window but obtain the full second or higher oder correlations.

PicoQuant offers several instruments such as time-tagging units and single photon sensitive detectors that can be used to study photon entanglement:

Time-tagging Units

MultiHarp 150 - High-Throughput Multichannel Event Timer & TCSPC UnitMultiHarp 150

High-Throughput Multichannel Event Timer & TCSPC Unit

  • 4, 8, or 16 independent input channels and common sync channel (up to 1.2 GHz)
  • High sustained data throughput (80 Mcps in time tagging mode, 180 Mcps in histogramming mode)
  • Record-breaking dead time (650 ps) per channel
  • No dead time across channels

HydraHarp 400 - Multichannel Picosecond Event Timer & TCSPC ModuleHydraHarp 400

Multichannel Picosecond Event Timer & TCSPC Module

  • Up to 8 independent input channels and common synch channel (up to 150 MHz)
  • Time channel width of 1 ps
  • Time tagging with sustained count rates up to 40 Mcps
  • USB 3.0 connection

PicoHarp 330 - Precise and Versatile Event Timer & TCSPC UnitPicoHarp 330

Precise and Versatile Event Timer & TCSPC Unit

  • Outstanding timing precision of 2 ps RMS for single channel, 3 ps RMS between channels
  • Cutting-edge time resolution of 1 ps
  • Choice of edge triggers or Constant Fraction Discriminators (CFD)
  • Sustained time tagging with up to 85 Mcps via USB 3.0 

TimeHarp 260 - TCSPC and MCS board with PCIe interfaceTimeHarp 260

TCSPC and MCS board with PCIe interface

  • One or two independent input channels and common synch channel (up to 84 MHz)
  • Two models with either 25 ps (PICO model) or 1 ns (NANO model) base resolution
  • Ultra short dead time (< 25 ns for PICO model, < 1 ns for NANO model)
  • PCIe interface

Single Photon Detectors

PDM SPAD - single photon sensitive detectorPDM Series

Single Photon Avalanche Diodes

  • Timing resolution down to < 50 ps (FWHM)
  • Detection efficiency up to 49%
  • Different active areas: 20, 50, and 100 µm
  • Ultra stable at high count rates


QuCoaQuCoa - Quantum Correlation Analysis Software

Quantum Correlation Analysis Software

  • Antibunching (g(2)) measurements including fitting to several models
  • Coincidence counting / event filtering, using AND, OR, NOT operators
  • Preview of antibunching curve and correlation data during measurement
  • Remote control via TCP/IP Interface

Latest 10 publications related to Quantum Entanglement

The following list is an extract of 10 recent publications from our bibliography that either bear reference or are releated to this application and our products in some way. Do you miss your publication? If yes, we will be happy to include it in our bibliography. Please send an e-mail to info@picoquant.com containing the appropriate citation. Thank you very much in advance for your kind co-operation.

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