Non-Equilibrium Quasiclassical Theory for Josephson Structures

TL;DR

This paper develops a non-equilibrium quasiclassical framework to analyze the ac properties of Josephson junctions, revealing complex dependencies on temperature, frequency, and phase, especially near phase difference pi due to zero energy bound states.

Contribution

It introduces a novel non-equilibrium formalism for Josephson structures that accurately satisfies self-consistency and enables detailed ac response analysis.

Findings

Strong temperature, frequency, and phase dependence of ac conductance.

Analytical and numerical results at low and arbitrary frequencies.

Identification of anomalous properties near phase difference pi.

Abstract

We present a non-equilibrium quasiclassical formalism suitable for studying linear response ac properties of Josephson junctions. The non-equilibrium self-consistency equations are satisfied, to very good accuracy, already in zeroth iteration. We use the formalism to study ac Josephson effect in a ballistic superconducting point contact. The real and imaginary parts of the ac linear conductance are calculated both analytically (at low frequencies) and numerically (at arbitrary frequency). They show strong temperature, frequency, and phase dependence. Many anomalous properties appear near phi = pi. We ascribe them to the presence of zero energy bound states.