We propose superconducting nanowire multi-photon detectors with simple bias and readout circuitry to count n-fold photon coincidences, where n is set by bias conditions. We present the concept, device architecture, and operating principle.
Single-photon detectors are ubiquitous devices in quantum-photonic-based communication, computation, metrology, and sensing. In these applications, N -fold coincidence photon counting is often needed, for example, to characterize entanglement. However, N -fold coincidence photon counting typically requires N individual single-photon detectors and associated bias and readout electronics, and these resources could become prohibitive if N goes large and the detectors need to work at cryogenic temperatures. Here, to break this limit on N , we propose a device architecture based on N cascaded photosensitive superconducting nanowires and one wider nanowire that functions as a current reservoir. We show that by strategically designing the device, the network of these superconducting nanowires can work in a synergic manner as an n -photon detector, where n can be from 1 to N , depending on the bias conditions. We therefore name the devices of this type superconducting nanowire multi-photon detectors (SNMPDs). In addition to its simple one-port bias and readout circuitry, the coincidences are counted internally in the detector, eliminating the need for external multi-channel, time-correlated pulse counters. We believe that the SNMPDs proposed in this work could open avenues towards conveniently measuring high-order temporal correlations of light and characterizing multi-photon entanglement.
Superconducting nanowires have emerged as a powerful tool for detecting single photons in the visible and near-infrared range with excellent device performance metrics. We outline challenges and future directions related to the up-scaling of nanowire devices and detector systems toward widespread applications in demanding real-world settings. Progress on achieving superconducting single-photon detectors with a large active area and an increasing number of pixels is reviewed, comparing the recent literature in terms of the reported key detector parameters. Furthermore, we summarize currently available readout and multiplexing schemes for multi-pixel detector arrays and discuss implications of the recently discovered microwire-based detector geometries.
A multi-element superconducting nanowire single photon detector (MESNSPD) is presented that consists of multiple independently-biased superconducting nanowire single photon detector (SNSPD) elements that form a continuous active area. A two-element SNSPD has been fabricated and tested, showing no measurable crosstalk between the elements, sub-50-ps relative timing jitter, and four times the maximum counting rate of a single SNSPD with the same active area. The MESNSPD can have a larger active area and higher speed than a single-element SNSPD and the input optics can be designed so that the detector provides spatial, spectral or photon number resolution.
Single-photon detectors based on superconducting nanowires (SSPDs or SNSPDs) have rapidly emerged as a highly promising photon-counting technology for infrared wavelengths. These devices offer high efficiency, low dark counts and excellent timing resolution. In this review, we consider the basic SNSPD operating principle and models of device behaviour. We give an overview of the evolution of SNSPD device design and the improvements in performance which have been achieved. We also evaluate device limitations and noise mechanisms. We survey practical refrigeration technologies and optical coupling schemes for SNSPDs. Finally we summarize promising application areas, ranging from quantum cryptography to remote sensing. Our goal is to capture a detailed snapshot of an emerging superconducting detector technology on the threshold of maturity.