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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.

Entangled 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

HydraHarp 400

Multichannel Picosecond Event Timer

  • 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 300

Compact Dual-Channel Picosecond Event Timer

  • Two identical synchronized but independent input channels
  • Time channel width of 4 ps
  • Time tagging with sustained count rates up to 5 Mcps
  • USB 2.0 connection

TimeHarp 260

Dead-time Free Coincidence Correlation

  • 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 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

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.