1996/11/30 by P. W. Brouwer, P.W. Brouwer, C. W. J. Beenakker +1 · 2 citations
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum chaos and dynamical systems #cond-mat.mes-hall
paper · pdf · doi:10.1016/s0960-0779(97)00018-0
published as Chaos, Solitons & Fractals 8, 1249 (1997) · 14 pages with 2 figures; the revision corrects the published version in Eqs. 8, 15, and 21d (with thanks to Marlies Goorden)
openalex publication_date 1997/07/01 · arxiv created 2004/08/27 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We calculate the supercurrent through a Josephson junction consisting of a phase-coherent metal particle (quantum dot), weakly coupled to two superconductors. The classical motion in the quantum dot is assumed to be chaotic on time scales greater than the ergodic time τerg, which itself is much smaller than the mean dwell time τdwell. The excitation spectrum of the Josephson junction has a gap Egap, which can be less than the gap Δ in the bulk superconductors. The average supercurrent is computed in the ergodic regime τerg ≪ ℏ/Δ, using random-matrix theory, and in the non-ergodic regime τerg ≫ ℏ/Δ, using a semiclassical relation between the supercurrent and dwell-time distribution. In contrast to conventional Josephson junctions, raising the temperature above the excitation gap does not necessarily lead to an exponential suppression of the supercurrent. Instead, we find a temperature regime between Egap and Δ where the supercurrent decreases logarithmically with temperature. This anomalously weak temperature dependence is caused by long-range correlations in the excitation spectrum, which extend over an energy range ℏ/τerg greater than Egap ≃ ℏ/τdwell. A similar logarithmic temperature dependence of the supercurrent was discovered by Aslamazov, Larkin, and Ovchinnikov, in a Josephson junction consisting of a disordered metal between two tunnel barriers.