FPGA-based gating and logic for multichannel single photon counting

Abstract

We present results characterizing multichannel InGaAs single photon detectors utilizing gated passive quenching circuits (GPQC), self-differencing techniques, and field programmable gate array (FPGA)-based logic for both diode gating and coincidence counting. Utilizing FPGAs for the diode gating frontend and the logic counting backend has the advantage of low cost compared to custom built logic circuits and current off-the-shelf detector technology. Further, FPGA logic counters have been shown to work well in quantum key distribution (QKD) test beds. Our setup combines multiple independent detector channels in a reconfigurable manner via an FPGA backend and post processing in order to perform coincidence measurements between any two or more detector channels simultaneously. Using this method, states from a multi-photon polarization entangled source are detected and characterized via coincidence counting on the FPGA. Photons detection events are also processed by the quantum information toolkit for application testing (QITKAT).

Keywords:

• optical instrumentation and technology
• single photon detector
• SPAD
• multichannel photon counting
• FPGA coincidence logic

Acknowledgements

T.S.H., D.D.E., and B.W. acknowledge support from the Defense Threats Reduction Agency. R.C.P. acknowledges support from the Department of Energy Office of Electricity. The authors thank A. Restelli and J. Bienfang at NIST for their knowledge and discussions on SPD gating. The authors also thank Craig Deibele at ORNL for his expertise in comb filters. This work was performed at Oak Ridge National Laboratory, operated by UT-Battelle for the U.S. Department of energy under Contract No. DE-AC05-00OR22725. The work has been authored by a contractor of the U.S. Government. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this work, or to allow others to do so for U.S. Government purposes.