Loss of Andreev Backscattering in Superconducting Quantum Point Contacts

TL;DR

This paper investigates how magnetic fields influence the energy spectrum and supercurrent in superconducting quantum point contacts, revealing the suppression of Andreev backscattering and the formation of a magnetic-field-dependent minigap.

Contribution

It introduces a new understanding of magnetic field effects on energy spectra and backscattering in superconducting quantum point contacts.

Findings

Magnetic field induces intermode transitions affecting electron wave propagation.

A minigap in the energy spectrum depends on the magnetic field strength.

Normal reflections couple states with opposite momenta, suppressing Andreev backscattering.

Abstract

We study effects of magnetic field on the energy spectrum in a superconducting quantum point contact. The supercurrent induced by the magnetic field leads to intermode transitions between the electron waves that pass and do not pass through the constriction. The latter experience normal reflections which couple the states with opposite momenta inside the quantum channel and create a minigap in the energy spectrum that depends on the magnetic field.