Long-range Josephson effect controlled by temperature gradient and circuit topology

TL;DR

This paper shows how supercurrent in superconducting nanostructures can be significantly increased and controlled by temperature gradients and circuit topology, with potential for experimental verification.

Contribution

It introduces a method to enhance and control Josephson supercurrent using temperature gradients and circuit topology in X-junctions, revealing new transition phenomena.

Findings

Supercurrent decays algebraically at T > Thouless energy

Temperature gradients can boost supercurrent to levels comparable to low T

Transitions between 0- and π-junction states are controllable by temperature and geometry

Abstract

We demonstrate that the supercurrent can be strongly enhanced in cross-like superconducting hybrid nanostructures (X-junctions) exposed to a temperature gradient. At temperatures T exceeding the Thouless energy of our X-junction the Josephson current decays algebraically with increasing T and can be further enhanced by a proper choice of the circuit topology. At large values of the temperature gradient the non-equilibrium contribution to the supercurrent may become as large as the equilibrium one at low T. We also predict a variety of transitions between 0- and $\pi$-junction states controlled by the temperature gradient as well as by the system geometry. Our predictions can be directly verified in modern experiments.