Protection of a qubit with a subradiance effect: Josephson quantum filter

TL;DR

This paper introduces a Josephson quantum filter that leverages subradiance effects to protect superconducting qubits from radiative decay via control lines, enabling scalable quantum computing.

Contribution

The paper proposes a passive Josephson quantum filter utilizing subradiance to shield data qubits without compromising gate speed.

Findings

JQF effectively reduces radiative decay in superconducting qubits.

The filter operates passively and is compatible with scalable systems.

Subradiance is harnessed for qubit protection in waveguide QED setups.

Abstract

The coupling between a superconducting qubit and a control line inevitably results in radiative decay of the qubit into the line. We propose a Josephson quantum filter (JQF), which protects the data qubit (DQ) from radiative decay through the control line without reducing the gate speed on DQ. JQF consists of a qubit strongly coupled to the control line to DQ, and its working principle is a subradiance effect characteristic to waveguide quantum electrodynamics setups. JQF is a passive circuit element and is therefore suitable for integration in a scalable superconducting qubit system.