Geometry-induced reduction of the critical current in superconducting nanowires

Henrich, D.; Reichensperger, Patrick; Hofherr, M.; Meckbach, J.M.; Ilin, K.; Siegel, M.; Semenov, A.; Zotova, A. N.; Vodolazov, D. Yu.

doi:10.1103/physrevb.86.144504

Cited by 67 publications

(54 citation statements)

References 24 publications

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“…More recently, Clem and Berggren 9 have theoretically demonstrated that sudden increases in the cross section of a transport bridge, as those caused by voltage leads, also produce current crowding effects and the consequent detriment of the critical current, similarly to right-angle bends. These predictions have been independently confirmed experimentally by Hortensius et al 10 and by Henrich et al 11 in submicron scale samples of NbTiN and NbN, respectively, and found to be also relevant in larger samples. 12 The effect of a magnetic field applied perpendicularly to the plane containing the superconducting wire with a sharp turn has been discussed in Refs.…”

supporting

confidence: 73%

Current crowding effects in superconducting corner-shaped Al microstrips

Adami

Cerbu

Cabosart

et al. 2013

Applied Physics Letters

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Enhanced upper critical field, critical current density, and thermal activation energy in new ytterbium doped CeFeAsO0.9F0.1 superconductor J. Appl. Phys. 113, 043924 (2013) Temperature-and field-dependent critical currents in [(Bi,Pb)2Sr2Ca2Cu3Ox]0.07(La0.7Sr0.3MnO3)0.03 thick films grown on LaAlO3 substrates J. Appl. Phys. 113, 043916 (2013) Transport critical current measurement apparatus using liquid nitrogen cooled high-Tc superconducting magnet with variable temperature insert Rev. Sci. Instrum. 84, 015113 (2013) Additional information on Appl. Phys. Lett.

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supporting

confidence: 73%

Current crowding effects in superconducting corner-shaped Al microstrips

Adami

Cerbu

Cabosart

et al. 2013

Applied Physics Letters

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“…The strength of the suppression is dependent on the particular geometry of the superconducting structure as well as on the angle and the radius r of the bend and the ratio of the coherence length to the width of the strip ξ GL /w. Several experiments by different groups [29][30][31] have confirmed the predictions of [28]. It has been shown that the current crowding is stronger for wider superconducting strips but becomes weaker with an increase of the radius of the bend.…”

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confidence: 58%

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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“…It is well known that the presence of current crowding in the bends of a wire can cause reduction of the device critical current by as much as 40% [42], with typical values of 10-20% [43]. We have assumed I b /I c ≈ 0.9 for all devices to produce Figure 4.…”

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confidence: 99%

Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector

et al. 2015

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We probe the local detection efficiency in a nanowire superconducting single-photon detector along the cross-section of the wire with a spatial resolution of 10 nm. We experimentally find a strong variation in the local detection efficiency of the device. We demonstrate that this effect explains previously observed variations in NbN detector efficiency as function of device geometry.Nanowire superconducting single-photon detectors (SSPDs) consist of a superconducting wire of nanoscale cross-section [1], typically 4 nm by 100 nm. Photon detection occurs when a single quantum of light is absorbed and triggers a transition from the superconducting to the normal state. SSPDs have high efficiency, low jitter, low dark count rate and fast reset time [2], and are therefore a key technology for, among others, quantum key distribution Although progress has been made recently, the underlying physical mechanism responsible for photon detection on the nanoscale is still under active investigation. A combination of theory [6,7], experiments [8][9][10] and simulations [11,12] on NbN SSPDs indicates that the absorption of a photon destroys Cooper pairs in the superconductor and creates a localized cloud of quasiparticles that diverts current across the wire. This makes the wire susceptible to the entry of a superconducting vortex from the edge of the wire. Energy dissipation by this moving vortex drives the system to the normal state.An important and unexpected implication of this detection model is a nanoscale position variation in the photodetection properties of the device. The conditions at the entry point of the vortex determine the energy required for it to cross the wire. This causes photons absorbed close to the edge to have a local detection efficiency (LDE) [13] compared to photons absorbed in the center of the wire [12]. This effect has practical implications for the operation of SSPDs, since it represents a potential limitation of the detection efficiency. In addition, SSPDs have been proposed for nanoscale sensing, either in a near-field optical microscope configuration [14] or as a subwavelength multiphoton probe [15], where this effect would be of major importance for the properties of such a microscope. While this effect has been predicted theoretically, clear experimental evidence is missing. * renema@physics.leidenuniv.nlIn this work, we experimentally explore the nanoscale variations in the intrinsic response of the detector. We spatially resolve the LDE with a resolution of approximately 10 nm, better than λ/50, using far-field illumination only. We find that our results are qualitatively consistent with numerical simulations [11,12]. Our results provide excellent quantitative agreement with experiments that indicate a polarization dependence in the LDE that was hitherto not understood [16].The key technique used in this work is a differential polarization measurement that probes the IDE of the detector (see Figure 1). The technique is based on the fact that polarized light is absorbed preferentially in dif...

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Geometry-induced reduction of the critical current in superconducting nanowires

Cited by 67 publications

References 24 publications

Current crowding effects in superconducting corner-shaped Al microstrips

Current crowding effects in superconducting corner-shaped Al microstrips

Detection mechanism of superconducting nanowire single-photon detectors

Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector

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