Adiabatic self-vibrations of a movable Cooper-pair box generated by inelastic Andreev tunneling

TL;DR

This paper proposes a novel scheme for self-sustained vibrations in a movable Cooper-pair box driven by inelastic Andreev tunneling, avoiding external feedback and leveraging adiabatic dynamics.

Contribution

It introduces an adiabatic, feedback-free method for inducing stable self-vibrations in a Cooper-pair box via inelastic Andreev tunneling.

Findings

Vibrational instability occurs in the adiabatic limit due to inelastic Andreev tunneling.

Nonlinear Josephson coupling saturates vibrational amplitude, enabling self-vibrations.

The scheme offers advantages over feedback-based self-oscillation methods.

Abstract

Self-sustained oscillators produce stable periodic motion robust to dissipation. Such motion is usually achieved by work fed back into the oscillator, but its performance is often limited by frequency-dependent operation. Here we propose a scheme for self-sustained vibrations without external feedback. We consider a movable Cooper-pair box attached to the free end of a voltage-biased normal-metal pillar. The Cooper-pair box carries an Andreev current subject to an electric field applied perpendicular to the current. In the adiabatic limit, where the Cooper-pair box state follows its motion, vibrational instability occurs, pumped by inelastic Andreev tunneling. Nonlinearity of the Josephson coupling saturates the vibrational amplitude, resulting in two-dimensional self-vibrations. We discuss the advantage of this adiabatic scheme in comparison with feedback-induced self-oscillation.