Quasiparticle dynamics in epitaxial Al-InAs planar Josephson junctions

TL;DR

This study investigates quasiparticle trapping and clearing in epitaxial Al-InAs Josephson junctions, revealing microsecond time-scale dynamics crucial for improving superconducting quantum circuit coherence.

Contribution

It provides the first detailed analysis of quasiparticle dynamics and associated time-scales in high transparency Al-InAs Josephson junctions, using a novel SQUID-based approach.

Findings

Quasiparticles can be trapped and cleared within a few microseconds.

Qp dynamics are consistent with electron-phonon relaxation times.

Qp trapping affects microwave loss and dissipation in the junction.

Abstract

Quasiparticle (QP) effects play a significant role in the coherence and fidelity of superconducting quantum circuits. The Andreev bound states of high transparency Josephson junctions can act as low-energy traps for QPs, providing a mechanism for studying the dynamics and properties of both the QPs and the junction. We study the trapping and clearing of QPs from the Andreev bound states of epitaxial Al-InAs Josephson junctions incorporated in a superconducting quantum interference device (SQUID) galvanically shorting a superconducting resonator to ground. We use a neighboring voltage-biased Josephson junction to inject QPs into the circuit. Upon the injection of QPs, we show that we can trap and clear QPs when the SQUID is flux-biased. We examine effects of the microwave loss associated with bulk QP transport in the resonator, QP-related dissipation in the junction, and QP poisoning events. By monitoring the QP trapping and clearing in time, we study the dynamics of these processes and find a time-scale of few microseconds that is consistent with electron-phonon relaxation in our system and correlated QP trapping and clearing mechanisms. Our results highlight the QP trapping and clearing dynamics as well as the associated time-scales in high transparency Josephson junctions based fabricated on Al-InAs heterostructures.