Dynamical parity selection in superconducting weak links

TL;DR

This paper presents a theoretical analysis of quasiparticle dynamics in superconducting weak links, demonstrating how microwave pulses can control parity states, with implications for quantum device performance.

Contribution

It introduces a new theoretical framework for controlling parity states in superconducting weak links using microwave pulses, explaining experimental observations.

Findings

Achieves near-perfect dynamical polarization of parity states.

Provides guidelines for efficient parity control in Andreev qubits.

Explains features observed in recent nanowire Josephson junction experiments.

Abstract

Excess quasiparticles play a crucial role in superconducting quantum devices ranging from qubits to quantum sensors. In this work we analyze their dynamics for phase-biased finite-length weak links with several Andreev subgap states, where the coupling to a microwave resonator allows for parity state (even/odd) readout. Our theory shows that almost perfect dynamical polarization in a given parity sector is achievable by applying a microwave pulse matching a transition in the opposite parity sector. Our results qualitatively explain key features of recent experiments on hybrid semiconducting nanowire Josephson junctions and provide theoretical guidelines for efficiently controlling the parity state of Andreev qubits.