Tunable coupling in circuit quantum electrodynamics with a superconducting V-system

TL;DR

This paper introduces a superconducting V-system qubit with tunable coupling to a cavity, enabling independent control of qubit energy and interaction strength, which is crucial for scalable quantum computing.

Contribution

It presents a novel superconducting charge qubit with a V-shaped spectrum that uses quantum interference for independent control of energy and coupling.

Findings

Achieved tunable coupling from <200 kHz to >40 MHz.

Demonstrated dynamic access to strong coupling regime.

Showed potential for protecting qubits from relaxation and unwanted interactions.

Abstract

Recent progress in superconducting qubits has demonstrated the potential of these devices for the future of quantum information processing. One desirable feature for quantum computing is independent control of qubit interactions as well as qubit energies. We demonstrate a new type of superconducting charge qubit that has a V-shaped energy spectrum and uses quantum interference to provide independent control over the qubit energy and dipole coupling to a superconducting cavity. We demonstrate dynamic access to the strong coupling regime by tuning the coupling strength from less than 200 kHz to more than 40 MHz. This tunable coupling can be used to protect the qubit from cavity-induced relaxation and avoid unwanted qubit-qubit interactions in a multi-qubit system.