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Integrated Hanbury Brown & Twiss Interferometer

The quPSI is composed of a (fiber based) beam splitter, two single photon detectors and a time-to-digital converter (TDC). The TDC records arrival times of detection events which are then evaluated to calculate the second order correlation function g(2)(τ).

The user can control the device via a graphical user interface or a library for Windows ® and Linux. Labview™ examples and an iPad App are also available. The software calculates the (2) function and offers several standard fitting functions e.g. for thermal light, anti-bunched light with or without detector timing jitter incorporated. These evaluations as well as the original data can be saved to files.

The single photon detectors are Silicon single photon avalanche detectors (SPADs or APDs) usable in a wavelength regime between 500 and 900 nm. The minimal bin width of the TDC is 81 ps. If the internal detectors do not fit the customer’s need, external detectors can be connected to the device, too. Furthermore, there is an external trigger input for example for life time measurements.

Key Features

  • Integrated HBT measurement system
  • Calculation of g(2) autocorrelation function
  • Fitting of standard functions
  • High timing resolution (min. bin width 81 ps)
  • Extra inputs for external detectors
  • External trigger for lifetime measurements
  • Easy to use


  • Characterization of single photon sources, e.g.:
    • Quantum dots
    • Diamont color centers
    • Single ions/ atoms
  • Photon statistics measurements (thermal, coherent, non-classical light sources)
  • Life time analysis

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