Operation of parallel SNSPDs at high detection rates

Abstract

Recent progress in the development of superconducting nanowire single-photon detectors (SNSPD) has delivered excellent performance, and their increased adoption has had a great impact on a range of applications. One of the key characteristic of SNSPDs is their detection rate, which is typically higher than other types of free-running single-photon detectors. The maximum achievable rate is limited by the detector recovery time after a detection, which itself is linked to the superconducting material properties and to the geometry of the meandered SNSPD. Arrays of detectors biased individually can be used to solve this issue, but this approach significantly increases both the thermal load in the cryostat and the need for time processing of the many signals, and this scales unfavorably with a large number of detectors. One potential scalable approach to increase the detection rate of individual detectors further is based on parallelizing smaller meander sections. In this way, a single detection temporarily disables only one subsection of the whole active area, thereby leaving the overall detection efficiency mostly unaffected. In practice however, cross-talk between parallel nanowires typically leads to latching, which prevents high detection rates. Here we show how this problem can be avoided through a careful design of the whole SNSPD structure. Using the same electronic readout as with conventional SNSPDs and a single coaxial line, we demonstrate detection rates over 200 MHz without any latching, and a fibre-coupled SDE as high as 77%, and more than 50% average SDE per photon at 50 MHz detection rate under continuous wave illumination.

Experimental entanglement generation for quantum key distribution beyond 1 Gbit/s

“…Most importantly, we have simultaneously assumed maximum detector count rates of 200 MHz. While such count rates can be achieved in state-of-the-art experiments [25], so far there exists no detection system simultaneously exhibiting high detection efficiency as well as low jitter. We note, however, that in (high-loss) long-distant communication scenarios, maximum count-rate limitations do not pose any practical problems for QKD implementations due to the reduced number of registered photons.…”

Experimental entanglement generation for quantum key distribution beyond 1 Gbit/s

“…Most importantly, we have simultaneously assumed maximum detector count rates of 200 MHz. While such count rates can be achieved in state-of-the-art experiments [25], so far there exists no detection system simultaneously exhibiting high detection efficiency and low jitter as well. We note, however, that in (high-loss) long-distant communication scenarios, maximum count-rate limitations do not pose any practical problems for QKD implementations due to the reduced number of registered photons.…”

“…But also in these cases, low jitter is crucial to avoid accidental two-fold clicks of uncorrelated photons. Thus, it becomes apparent that although recent research shows promising approaches [25][26][27], detector technology has yet to catch up with high-end entangled-photon-pair sources such as the one presented in this work.…”

Mid-infrared photon counting with superconducting nanowires

“…The maximum count rate of SNSPDs is another area that has been pushed in recent years. Designs such as interleaving multiple shorter nanowires to reduce the kinetic inductance [207] and connecting multiple devices in parallel [208] have boosted the maximum count rate of the detectors to the GHz regime. Lastly, scaling devices up to large areas is an intense area of ongoing research.…”