Manipulation with Andreev states in spin active mesoscopic Josephson junctions

TL;DR

This paper explores the control of Andreev bound states in magnetic Josephson junctions, demonstrating Rabi oscillations driven by magnetic and phase modulation, revealing complex dynamics and spin polarization effects.

Contribution

It introduces a method to manipulate Andreev states in magnetic Josephson junctions using magnetic and phase driving, highlighting unique properties like 4π-periodicity and spin polarization.

Findings

Observation of Rabi oscillations in Andreev states

Detection of oscillating Josephson current and spin polarization

Identification of a selection rule forbidding certain transitions

Abstract

We investigate manipulation with Andreev bound states in Josephson quantum point contacts with magnetic scattering. Rabi oscillations in the two-level Andreev subsystems are excited by resonant driving the direction of magnetic moment of the scatterer, and by modulating the superconducting phase difference across the contact. The Andreev level dynamics is manifested by temporal oscillation of the Josephson current, accompanied, in the case of magnetic manipulation, also by oscillation of the Andreev states spin polarization. The interlevel transitions obey a selection rule that forbids manipulations in a certain region of external parameters, and results from specific properties of Andreev bound states in magnetic contacts: 4$\pi$-periodicity with respect to the superconducting phase, and strong spontaneous spin polarization.