2.23 GHz gating InGaAs/InP single-photon avalanche diode for quantum key distribution

TL;DR

This paper reports the development of a 2.23 GHz InGaAs/InP single-photon avalanche diode suitable for high-rate quantum key distribution, demonstrating performance comparable to superconducting detectors and addressing afterpulsing issues.

Contribution

The paper introduces the fastest gating InGaAs/InP SPAD at 2.23 GHz and a new method to characterize afterpulsing for rapid gating regimes, enhancing QKD performance.

Findings

Achieved 2.23 GHz gating frequency approaching SPAD bandwidth limit.

Demonstrated Mbps key rates for distances less than 40 km.

Extended maximum QKD distance to ~190 km with longer deadtime.

Abstract

We implement an InGaAs/InP single-photon avalanche diode (SPAD) for single-photon detection with the fastest gating frequency reported so far, of 2.23 GHz, which approaches the limit given by the bandwidth of the SPAD - 2.5 GHz. We propose a useful way to characterize the afterpulsing distribution for rapid gating that allows for easy comparison with conventional gating regimes. We compare the performance of this rapid gating scheme with free-running detector and superconducting single-photon detector (SSPD) for the coherent one-way quantum key distribution (QKD) protocol. The rapid gating system is well suited for both high-rate and long-distance QKD applications, in which Mbps key rates can be achieved for distances less than 40 km with 50 ns deadtime and the maximum distance is limited to ~190km with 5 $\mu$s deadtime. These results illustrate that the afterpulsing is no longer a limiting factor for QKD.