Photon-number-resolving (PNR) is an important functionality in many applications. The traditional single photon detectors (SNSPDs) operated with the conventional readout scheme does not have the PNR functionality. In this paper, we demonstrate a superconducting photon-number-resolving detector operating at the visible wavelength regime, based on the serial connection of six superconducting nanowires. The results of our 6-element PNR device show clear evidence of n-photons differentiation with n ranging from 1 to 6. The system detection efficiency reaches 54% with the dark counts rate below 10 Hz at 660 nm. The demonstrated 6-element PNR device does not require a complex readout circuit compared with the SNSPD array device, and is expected to have wider applications in addition to imaging and communication.
Photon-number-resolving (PNR) is an important functionality in many applications. The traditional single photon detectors (SNSPDs) operated with the conventional readout scheme does not have the PNR functionality. In this paper, we demonstrate a superconducting photon-number-resolving detector operating at the visible wavelength regime, based on the serial connection of six superconducting nanowires. The results of our 6-element PNR device show clear evidence of n-photons differentiation with n ranging from 1 to 6. The system detection efficiency reaches 54% with the dark counts rate below 10 Hz at 660 nm. The demonstrated 6-element PNR device does not require a complex readout circuit compared with the SNSPD array device, and is expected to have wider applications in addition to imaging and communication.
Abstract A series superconducting nanowire single-photon detector is a high performance nanowire array detector that has the potential to reach a high system detection efficiency (SQE), a high counting rate (CR) and photon number resolving functionality. Interconnected with a simplified readout, it shows promise for large scale expansion and has good prospects for future applications in single-photon imaging, quantum optics, quantum computing and deep-space communication. In this paper, we demonstrate a high SQE and CR series superconducting nanowire single-photon detector with an active area of 20 × 20 μ m 2 . The detector shows a maximum SQE of 68% at 1550 nm with a dark count rate of 200 Hz and a wide response wavelength from 1100–2000 nm. It also achieves a CR over 300 MHz at single photon power level and has the capability of resolving photon numbers by up to six photons.
Since their first demonstration in 2001, superconducting-nanowire single-photon detectors have witnessed two decades of great developments. SNSPDs are the detector of choice in most modern quantum optics experiments and are slowly finding their way into other photon starved fields of optics. Until now, however, in nearly all experiments SNSPDs were used as binary detectors, meaning they can only distinguish between 0 and more than 1 photons and photon number information is lost. Recent research works have demonstrated proof of principle photon number resolving (PNR) SNSPDs counting 2 to 5 photons. The photon-number-resolving capability is highly demanded in various quantum-optics experiments, including HOM interference, photonic quantum computing, quantum communication, and non Gaussian quantum state preparation. In particular, PNR detectors at the wavelength range of 850 to 950 nm are of great interest due to the availability of high quality semiconductor quantum dots and high-performance Cesium-based quantum memories. In this paper, we demonstrate NbTiN based SNSPDs with over 94 percent system detection efficiency, sub 11 ps timing jitter for one photon, and sub 7 ps for two photon. More importantly, our detectors resolve up to 7 photons using conventional cryogenic electric readout circuitry. Through theoretical analysis, we show that the current PNR performance of our detectors can still be further improved by improving the signal to noise ratio and bandwidth of our readout circuitry. Our results are promising for the future of optical quantum computing and quantum communication.
We present the experimental demonstration of a superconducting photon number resolving detector. It is based on the series connection of N superconducting nanowires, each connected in parallel to an integrated resistor. The device provides a single voltage readout, proportional to the number of photons absorbed in distinct nanowires. Clearly separated output levels corresponding to the detection of n=1-4 photons are observed in a 4-element detector fabricated from an NbN film on GaAs substrate, with a single-photon system quantum efficiency of 2.6% at the wavelength of 1300nm. The series-nanowire structure is promising in view of its scalability to large photon numbers and high efficiencies.
The experimental demonstration of a superconducting photon-number-resolving detector, based on the series connection of N superconducting nanowires, is presented. An integrated resistor is connected in parallel to each section of the device that provides in this way a single voltage-readout, proportional to the number of photons detected in distinct nanowires. As a proof of principle a four element detector has been fabricated from an NbN film on a GaAs substrate and fully characterized. Clearly separated output levels corresponding to the detection of n = 1 – 4 photons are observed achieving a single-photon system quantum efficiency of 2.6% at λ=1.3 μm. In order to demonstrate the potential scalability of the series-nanowire detector to a larger number of photons, we report our preliminary results in the characterization of detectors fabricated with 8 and 12 pixels. Clear evidence of n= 1-8 photon absorption in the 8-pixel detector has been achieved.
Abstract In recent years, photon-number-resolving (PNR) detectors have attracted great interest, mainly because they can play a key role in diverse application fields. A PNR detector with a large dynamic range would represent an ideal photon detector, bringing the linear response of conventional analogue detectors down to the single-photon level. Several technologies, such as InGaAs single photon avalanche detectors (SPADs), arrays of silicon photomultipliers, InGaAs SPADs with self-differencing circuits and transition edge sensors have shown photon number resolving capability. Superconducting nanowires provide free-running single-photon sensitivity from visible to mid-infrared frequencies, low dark counts, excellent timing resolution (<60 ps) and short dead time (∼10 ns), at an easily accessible temperature (2–3 K), but they do not inherently resolve the photon number. In this framework, PNR detectors based on arrays of superconducting nanowires have been proposed. In this article we describe a number of methods and device configurations that have been pursued to obtain PNR capability using superconducting nanowire detectors.
Since their first demonstration in 2001 [Gol’tsman et al., Appl. Phys. Lett. 79, 705–707 (2001)], superconducting-nanowire single-photon detectors (SNSPDs) have witnessed two decades of great developments. SNSPDs are the detector of choice in most modern quantum optics experiments and are slowly finding their way into other photon-starved fields of optics. Until now, however, in nearly all experiments, SNSPDs were used as “binary” detectors, meaning that they could only distinguish between 0 and >=1 photons, and photon number information was lost. Recent research has demonstrated proof-of-principle photon-number resolution (PNR) SNSPDs counting 2–5 photons. The photon-number-resolving capability is highly demanded in various quantum-optics experiments, including Hong–Ou–Mandel interference, photonic quantum computing, quantum communication, and non-Gaussian quantum state preparation. In particular, PNR detectors at the wavelength range of 850–950 nm are of great interest due to the availability of high-quality semiconductor quantum dots (QDs) [Heindel et al., Adv. Opt. Photonics 15, 613–738 (2023)] and high-performance cesium-based quantum memories [Ma et al., J. Opt. 19, 043001 (2017)]. In this paper, we demonstrate NbTiN-based SNSPDs with >94% system detection efficiency, sub-11 ps timing jitter for one photon, and sub-7 ps for 2 photons. More importantly, our detectors resolve up to 7 photons using conventional cryogenic electric readout circuitry. Through theoretical analysis, we show that the PNR performance of demonstrated detectors can be further improved by enhancing the signal-to-noise ratio and bandwidth of our readout circuitry. Our results are promising for the future of optical quantum computing and quantum communication.