FPGA-based signal generation and readout of SNSPD signals for quantum communication

We perform the first experimental demonstration of using an FPGA-based radio frequency system-on-chip (RFSoC) architecture from Xilinx as the main electronics components of a quantum network by producing entangled photon-pairs and measuring its entanglement quality.  Using a standard entangled photon-pair source, we constructed a simple demonstrator experiment illustrating the use of the RFSoC-FPGA in photonic time-bin encoded quantum networks.

One key component in producing time-bin encoded photons is a radio-frequency pulse generator. We demonstrate that using the digital-to-analog converters of the FPGA is comparable to commercial arbitrary waveform generators (AWG) by characterizing the coincidence-to-accidental ratio (CAR) and the entanglement visibility of the entangled photon-pair source in the x-basis. We measured a CAR as high as 154, in agreement with the CAR measured with AWG and a high entanglement visibility of 95%.

Finally, we also demonstrate the use of the RFSoC-FPGA in the detection of the photon signals from superconducting nanowire single photon detectors (SNSPDs). We show that the CAR measured using the custom digitizer firmware and pulse-shape reconstruction software is comparable to that measured using commercial time-to-digital converter.