Electron-phonon interactions in the Andreev Bound States of aluminum nanobridge Josephson junctions

TL;DR

This study investigates quasiparticle trapping and clearing in aluminum nanobridge Josephson junctions, revealing temperature-dependent mechanisms and complex behaviors that impact quasiparticle dynamics in superconducting qubits.

Contribution

It provides detailed experimental insights into quasiparticle interactions with Andreev Bound States, highlighting temperature effects and complex energy dependencies in nanobridge junctions.

Findings

Trapping modeled by independent spontaneous emission events

Thermal phonons dominate clearing above 80 mK

Low-temperature clearing involves temperature-independent mechanisms

Abstract

We report continuous measurements of quasiparticles trapping and clearing from Andreev Bound States in aluminum nanobridge Josephson junctions integrated into a superconducting-qubit-like device. We find that trapping is well modeled by independent spontaneous emission events. Above 80 mK the clearing process is well described by absorption of thermal phonons, but other temperature-independent mechanisms dominate at low temperature. We find complex structure in the dependence of the low-temperature clearing rate on the Andreev Bound State energy. Our results shed light on quasiparticle behavior in qubit-like circuits.