Towards a Multi-Pixel Photon-to-Digital Converter for Time-Bin Quantum Key Distribution

Simon Carrier; Michel Labrecque-Dias; Ramy Tannous; Pascal Gendron; Frédéric Nolet; Nicolas Roy; Tommy Rossignol; Frédéric Vachon; Samuel Parent; Thomas Jennewein; Serge Charlebois; Jean-François Pratte

doi:10.3390/s23073376

Towards a Multi-Pixel Photon-to-Digital Converter for Time-Bin Quantum Key Distribution

Sensors (Basel). 2023 Mar 23;23(7):3376. doi: 10.3390/s23073376.

Affiliations

¹ Département de Génie Électrique et de Génie Informatique, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
² Institute for Quantum Computing, Department of Physics & Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada.

Abstract

We present an integrated single-photon detection device custom designed for quantum key distribution (QKD) with time-bin encoded single photons. We implemented and demonstrated a prototype photon-to-digital converter (PDC) that integrates an 8 × 8 single-photon avalanche diode (SPAD) array with on-chip digital signal processing built in TSMC 65 nm CMOS. The prototype SPADs are used to validate the QKD functionalities with an array of time-to-digital converters (TDCs) to timestamp and process the photon detection events. The PDC uses window gating to reject noise counts and on-chip processing to sort the photon detections into respective time-bins. The PDC prototype achieved a 22.7 ps RMS timing resolution and demonstrated operation in a time-bin setup with 158 ps time-bins at an optical wavelength of 410 nm. This PDC can therefore be an important building block for a QKD receiver and enables compact and robust time-bin QKD systems with imaging detectors.

Keywords: CMOS detector; QEYSSat; free-space; photon-to-digital converter (PDC); quantum cryptography; quantum internet; quantum key distribution (QKD); single-photon avalanche diode (SPAD); time-bin encoding; time-to-digital converter (TDC).

Grants and funding

This research was funded by Institut Quantique (Université de Sherbrooke) and the Institute of Quantum Computing (University of Waterloo) thanks to the Canadian First Research Excellence Fund (CFREF) program and J.-F. Pratte’s and T. Jennewein’s NSERC Discovery Grant. CMC Microsystems provided funding for chip fabrication, equipment, and software. S. Carrier’s salary was partially funded by scholarships from NSERC and FRQNT. R. Tannous acknowledges support from a NSERC graduate scholarship.