Scalable readout interface for superconducting nanowire single-photon detectors using AQFP and RSFQ logic families

Abstract

We propose a scalable readout interface for superconducting nanowire singlephoton detector (SSPD) arrays, which we call the AQFP/RSFQ interface. This interface is composed of adiabatic quantum flux parametron (AQFP) and rapid single flux quantum (RSFQ) logic families. The AQFP part reads out the spatial information of an SSPD array via a single cable, and the RSFQ part reads out the temporal information via a single cable. The hybrid interface has high temporal resolution owing to low timing jitter in the operation of the RSFQ part. In addition, the hybrid interface achieves high circuit scalability because of low supply current in the operation of the AQFP part. Therefore, the hybrid interface is suitable for handling many-pixel SSPD arrays. We demonstrate a four-pixel SSPD array using the hybrid interface as proof of concept. The measurement results show that the hybrid interface can read out all of the pixels with a low error rate and low timing jitter.

Adiabatic Quantum-Flux-Parametron: A Tutorial Review

“…Figure 12(b) shows a micrograph of a hybrid interface fabricated using the AIST 2.5 kA/cm 2 Nb standard process (STP2) [97]. As a proof of concept, we demonstrated a four-pixel SSPD array using the hybrid interface and found that each pixel was read out with low error rates and low timing jitter [46]. The next step is to develop hybrid interfaces for large-scale SSPD arrays.…”

“…We have established the design methodology for AQFP logic and recently succeeded in demonstrating a 4-bit microprocessor [10]. We have also developed various systems by exploiting the physical features of the AQFP, such as reversible computers [43,44], single-photon image sensors [45,46], and stochastic electronics [47,48]. This indicates the potential of AQFP logic to be widely used in future ICT.…”

“…We note that, in addition to energy efficiency, many other factors, such as clock speed, circuit density, and cooling overhead, should be also taken into account in actual circuit design. Therefore, it is crucial to select the best logic family and/or combine multiple logic families [46,62] for each application, since every logic family has different advantages and disadvantages.…”

“…We demonstrated a single-pixel SSPD implemented with an AQFP comparator in a 0.1-W Gifford-McMahon (GM) cryocooler [96] to verify that AQFP logic has sufficient sensitivity to sample the signal currents from an SSPD. Furthermore, we proposed a readout circuit for large-scale SSPD arrays, the AQFP/RSFQ hybrid interface [46], which combines AQFP and RSFQ logic families to achieve both high scalability and high time resolution. Figure 12(b) shows a micrograph of a hybrid interface fabricated using the AIST 2.5 kA/cm 2 Nb standard process (STP2) [97].…”

Impedance Design of Excitation Lines in Adiabatic Quantum-Flux-Parametron Logic Using InductEx

“…UPERCONDUCTOR logic families [1]- [4] are crucial for achieving cryogenic information systems, such as energyefficient microprocessors [5], [6], single-photon image sensors [7], [8], and quantum computers [9], [10]. We have been investigating adiabatic quantum-flux-parametron (AQFP) logic [11], which is an adiabatic logic family based on the quantum flux parametron (QFP) [12], [13].…”