Development of superconducting nanowire single-photon detector with ultra-low dark count rate

M. Hofherr, Dagmar Rall, K. Ilin +3 more

Carsten Schuck, Wolfram H. P. Pernice, Hong X. Tang

Superconducting nanowire single-photon detectors are an ideal match for integrated quantum photonic circuits due to their high detection efficiency for telecom wavelength photons. Quantum optical technology also requires single-photon detection with low dark count rate and high timing accuracy. Here we present very low noise superconducting nanowire single-photon detectors based on NbTiN thin films patterned directly on top of Si3N4 waveguides. We systematically investigate a large variety of detector designs and characterize their detection noise performance. Milli-Hz dark count rates are demonstrated over the entire operating range of the nanowire detectors which also feature low timing jitter. The ultra-low dark count rate, in combination with the high detection efficiency inherent to our travelling wave detector geometry, gives rise to a measured noise equivalent power at the 10(-20) W/Hz(1/2) level.

Taro Yamashita, Shigehito Miki, Kazumasa Makise +5 more

A. Bahgat Shehata, Alessandro Ruggeri, Franco Stellari +6 more

Today Superconducting Nanowire Single-Photon Detectors (SNSPDs) are commonly used in different photon-starved applications, including testing and diagnostics of VLSI circuits. Detecting very faint signals in the near-infrared wavelength range requires not only good detection efficiency, but also very low Dark Count Rate (DCR) and jitter. For example, low noise is crucial to enable ultra-low voltage optical testing of integrated circuits. The effect of detector temperature and background thermal radiation on the noise of superconducting single-photon detectors made of NbN meanders is studied in this paper. It is shown that two different regimes can be identified in the DCR vs. bias current characteristics. At high bias, the dark count rate is dominated by the intrinsic noise of the detector, while at low bias current it is dominated by the detection of stray photons that get onto the SNSPD. Changing the detector temperature changes its switching current and only affects the high bias branch of the characteristics: a reduction of the DCR can be achieved by lowering the SNSPD base temperature. On the other hand, changing the temperature of the single-photon light source (e.g. the VLSI circuit under test) only affects the low bias regime: a lower target temperature leads to a smaller DCR.

M. Hofherr, Dagmar Rall, K. Ilin +4 more

For superconducting nanowire single-photon detectors \n(SNSPD), there is a wide market of applications, like correlation spectroscopy or quantum cryptography, that profits from detectors with large speed and high detection efficiency. SNSPDs made of ultra-thin NbN films, patterned as a meander nanowire with a width in the range of 100 nm, offer a great change for the future to cover these specifications. NbN has been proven to be an excellent material for the development of SNSPD. \nIn context of high detection efficiency, a very low dark count rate is needed to satisfy the demands of several applications. Former studies show, that there is a certain relation between the detection mechanism and the dark counts [1], [2]. The origin of dark counts is due to thermal fluctuations in the meander structure of a SNSPD. To reduce this dark count rate, an investigation \nof influence of cooling conditions on the dark counts is \nnecessary.

Jia-Hao Hu, Wei-Jun Zhang, Wen-Shuo Yu +7 more

We experimentally demonstrate an improved optical biasing scheme for superconducting nanowire single-photon detectors (SNSPDs), which employs a cryogenic InGaAs-InP photodiode (PD) as a local bias source. It is found that, under illumination from a stable external light source, this PD generates a stable photocurrent in a cryogenic environment (~2.3 K), with fluctuations in the photocurrent primarily attributed to fluctuations in the incident optical power. Furthermore, by screening and effectively blocking stray photons leaking from the PD, which give rise to background dark counts, we have achieved an SNSPD exhibiting an ultra-low intrinsic dark count rate of 1e-4 cps. Utilizing this improved optical biasing technique, our SNSPD achieved performance comparable to that obtained under conventional electrical biasing: a system detection efficiency of 80.7%, a background dark count rate of 32.6 cps, and a minimum timing jitter of 57.5 ps. These results indicate that cryogenic-PD-based optical biasing serves as a viable, low-noise, and low-jitter alternative to traditional electrical biasing. Moreover, this work offers useful design guidance for the future development of PD-based low-noise bias sources and for the construction of all-photonic SNSPD systems tailored for high-precision quantum photonics applications.