Evanescent states and nonequilibrium in driven superconducting nanowires

Abstract

We study the nonlinear response of current transport in a superconducting diffusive nanowire between normal reservoirs. We demonstrate theoretically and experimentally the existence of two different superconducting states appearing when the wire is driven out of equilibrium by an applied bias, called the global and bimodal superconducting states. The different states are identified by using two-probe measurements of the wire, and measurements of the local density of states with tunneling probes. The analysis is performed within the framework of the quasiclassical kinetic equations for diffusive superconductors.

Nonequilibrium interpretation of DC properties of NbN superconducting hot electron bolometers

“…The approach to this point is not observable in the I, V curves because as long as the material stays superconducting, i.e., carries a supercurrent, it does not contribute to the voltage. However, in the model of Keizer et al 6 and Vercruyssen et al 7 it is assumed that the length of the superconducting wire is short compared to the electronelectron interaction time s ee , leading to the parameter range n < L < K ee . Consequently, a position-dependent non-thermal 2-step distribution function occurs as for normal metal wires studied by Pothier et al 12 For NbN, this assumption is not justified because the electron-electron interaction time s ee is estimated to be 2:5 ps (see Annunziata 13 ) or 6:5 ps (see Il'in et al…”

Engineering Physics of Superconducting Hot-Electron Bolometer Mixers

“…Hence, one can easily be in the regime L << ξ, Λ ee , like in the case of hot-electron bolometers studied by Prober 21 (Prober, 1993) and Siddiqi et al (Siddiqi et al, 2002). One can also perform experiments in the regime ξ < L < Λ ee (Boogaard et al, 2004;Keizer et al, 2006;Vercruyssen et al, 2012). For niobium one has usually an intermediate regime with ξ of about 40 nm and Λ ee of 100 nm (Gershenzon et al, 1990), which was studied by Burke et al (Burke et al, 1999(Burke et al, , 1996.…”

“…Due to the small supercurrent, the voltage profile is almost equal to the normal state. (Reproduced with permission from the authors (Vercruyssen et al, 2012)) lowed by experimental work (Vercruyssen et al, 2012).…”

YBCO-Constriction Hot Spot Modeling: DC and RF Descriptions for HEB THz Mixer Noise Temperature and Conversion Gain

“…Equations (1) and (2) are depicting a phonon cooled device, because cooling by the electron diffusion to the metal contacts can be neglected in YBCO [9], as opposed to Nb HEBs [17] or superconducting metallic nanowires [18], [19]. τ ep is the electron-phonon relaxation time in YBCO and τ esc the phonon escape time from YBCO film to the substrate.…”