Single-photon imager based on a superconducting nanowire delay line

Abstract

Detecting spatial and temporal information of individual photons by using singlephoton-detector (SPD) arrays is critical to applications in spectroscopy, communication, biological imaging, astronomical observation, and quantum-information processing. Among the current SPDs 1 , detectors based on superconducting nanowires have outstanding performance 2 , but are limited in their ability to be integrated into large scale arrays due to the engineering difficulty of high-bandwidth cryogenic electronic readout [3][4][5][6][7][8] . Here, we address this problem by demonstrating a scalable single-photon imager using a single continuous photon-sensitive superconducting nanowire microwave-plasmon transmission line. By appropriately designing the nanowire's local electromagnetic environment so that the nanowire guides microwave plasmons, the propagating voltages signals generated by a photon-detection event were slowed down to ~ 2% of the speed of light. As a result, the time difference between arrivals of the signals at the two 2 ends of the nanowire naturally encoded the position and time of absorption of the photon. Thus, with only two readout lines, we demonstrated that a 19.7-mm-long nanowire meandered across an area of 286 μm × 193 μm was capable of resolving ~ 590 effective pixels while simultaneously recording the arrival times of photons with a temporal resolution of 50 ps. The nanowire imager presents a scalable approach to realizing high-resolution photon imaging in time and space. Main Text:Quantum and classical optics are currently limited by our ability to efficiently sense and process information about single photons. For example, to enhance the information-carrying capacity of a quantum channel 9 and improve security in quantum key distribution 10,11 , information is typically encoded in the position and arrival time of individual photons.Determining the spatial and temporal information of photons is currently accomplished by single-photon detector (SPD) arrays. Among existing SPD array technologies, the transition edge sensor (TES) and the microwave kinetic inductance detector (MKID) provide moderate spectral information but less impressive temporal resolution (e.g., the timing jitter is measured in nanoseconds for TESs 12 and microseconds for MKIDs 13 ). Photomultiplier tubes and singlephoton avalanche diodes have sub-1-ns timing jitter in the visible domain, but their detection performance deteriorates in the infrared, and scaling these technologies to large spatial arrays is challenging 1 . Improved timing performance of sub-20-ps timing jitter 14 and sub-10-ns recovery time 15 is possible with superconducting-nanowire single-photon detectors (SNSPDs), which also have been demonstrated to have near-unity detection efficiency 2 , less than 1 dark-count per second (cps) 16 , a wide spectral response from the visible to infrared 17 and greater than 100 cps 3 counting rate 18 . However, attempts to create arrays of SNSPDs have had limited success 3-8 .Traditional row-column rectangular pixel arra...

Single-Photon Single-Flux Coupled Detectors

“…[6], we have attributed this discrepancy to underestimating the kinetic inductivity increase in the shunted region due to suppression of superconductivity (the calculations assume a single L k value which is estimated for the unshunted region). Furthermore, we have also observed that the relative alignment of the metal and the NbN heavily influenced the biasing conditions 3 . This behavior also suggests large kinetic inductivity difference between the shunted and the unshunted regions and requires placement of the metal layer as close as possible to (but not in contact with) the yTron.…”

“…Detection of single-photons is essential to applications such as optical communications, astronomical measurements, and quantum-information processing. Superconducting nanowire single-photon detectors (SNSPDs) are prominent tools for these applications because of their > 90% detection efficiencies, near GHz count rates, few picosecond timing jitter, broad spectral sensitivity from ultra-violet to infrared wavelengths, and sub-Hz dark count rates [1,2,3].…”

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“…As recent research results indicate, they can in principle resolve photon numbers, but as of now there is no practicable and commercially available implementation using this capability. The same holds true for achieving 2D spatial resolution or the arrangement as 1D detector array …”

High Sensitivity Photodetector for Photon-Counting Applications

“…Cryogenic-based single-photon detectors demonstrate high quantum efficiency (QE) at visible and near-infrared (NIR) wavelengths [10], low dark count rate, picosecond pulse-to-pulse timing jitter, and a gigahertz counting rate. SnSPDs are also recently being used with "imaging" capabilities [13].…”