Three Temperature Regimes in Superconducting Photon Detectors: Quantum, Thermal and Multiple Phase-Slips as Generators of Dark Counts

We report on measurements of the switching current distributions on two-dimensional superconducting NbTiN strips that are 5 nm thick and 80 nm wide. We observe that the width of the switching current distributions has a non-monotonous temperature dependence, where it is constant at the lowest temperatures up to about 1.5 K, after which it increases with temperature until 2.2 K. Above 2.5 K any increase in temperature decreases the distribution width which at 4.0 K is smaller than half the width observed at 0.3 K. By using a careful analysis of the higher order moments of the switching distribution, we show that this temperature dependence is caused by switching due to multiple fluctuations. We also find that the onset of switching by multiple events causes the current dependence of the switching rate to develop a characteristic deviation from a pure exponential increase, that becomes more pronounced at higher temperatures, due to the inclusion of higher order terms.

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“…Murphy et al . 12 has recently investigated “[…] quantum, thermal and multiple phase slips as generators of dark counts” in quasi-2D NbN strips.…”

Section: Introductionmentioning

confidence: 99%

Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips

Ejrnæs

Salvoni

Parlato

et al. 2019

Sci Rep

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“…We take t = 0.2 and   At finite current, the measured sheet resistance is several orders of magnitude larger than the theory would suggest. Typical dark count rates in similar nanowires at 1.5 K are ~10 2 -10 4 Hz, 17 with each dark count corresponding to the creation of a resistive region with a resistance of ≈ 6 k for a duration of ≈0.25 ns. 18 The resulting time-average resistance due to dark counts is too low to explain the observed behavior.…”

Section: B Current Dependencementioning

confidence: 99%

Microwave dynamics of high aspect ratio superconducting nanowires studied using self-resonance

Santavicca

Adams

Grant

et al. 2016

Journal of Applied Physics

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We study the microwave impedance of extremely high aspect ratio (length/width ≈ 5,000) superconducting niobium nitride nanowires. The nanowires are fabricated in a compact meander geometry that is in series with the center conductor of a 50  coplanar waveguide transmission line. The transmission coefficient of the sample is measured up to 20 GHz. At high frequency, a peak in the transmission coefficient is seen. Numerical simulations show that this is a half-wave resonance along the length of the nanowire, where the nanowire acts as a high impedance, slow wave transmission line. This resonance sets the upper frequency limit for these nanowires as inductive elements. Fitting simulations to the measured resonance enables a precise determination of the nanowire's complex sheet impedance at the resonance frequency. The real part is a measure of dissipation, while the imaginary part is dominated by kinetic inductance. We characterize the dependence of the sheet resistance and sheet inductance on both temperature and current and compare the results to recent theoretical predictions for disordered superconductors. These results can aid in the understanding of high frequency devices based on superconducting nanowires. They may also lead to the development of novel superconducting devices such as ultra-compact resonators and slowwave structures.2

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“…A temperature-dependent study [69] revealed a growing inconsistency between theory and experiment at temperatures below ≈ 2.5 K ¶. Very recently, the switching current distributions as a function of temperature in typical meander structures as used for SNSPD have been measured [70]. A detailed statistical analysis suggests that at temperatures T 2 K dark counts may not be thermally activated, but caused by quantum-mechanical tunneling events, so called QPS.…”

Section: Dark Countsmentioning

confidence: 99%

Detection mechanism of superconducting nanowire single-photon detectors

Engel¹,

Renema²,

Ilin³

et al. 2015

Supercond. Sci. Technol.

149

111

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Abstract. In this paper we intend to give a comprehensive description of the current understanding of the detection mechanism in superconducting nanowire singlephoton detectors. We will review key experimental results related to the detection mechanism, e.g. the variations of the detection probability as a function of bias current, temperature or magnetic field. Commonly used detection models will be introduced and we will analyze their predictions in view of the experimental observations. Although none of the proposed detection models is able to describe all experimental data, it is becoming increasingly clear that vortices are essential for the formation of the initial normal-conducting domain that triggers a detection event.

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Three Temperature Regimes in Superconducting Photon Detectors: Quantum, Thermal and Multiple Phase-Slips as Generators of Dark Counts

Cited by 31 publications

References 46 publications

Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips

Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips

Microwave dynamics of high aspect ratio superconducting nanowires studied using self-resonance

Detection mechanism of superconducting nanowire single-photon detectors

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