Switchable coupling between charge and flux qubits

TL;DR

This paper proposes a hybrid quantum circuit with switchable coupling between charge and flux qubits via a large Josephson junction, enabling quantum state transfer and storage at optimal points.

Contribution

It introduces a controllable inter-qubit coupling mechanism in a hybrid circuit, facilitating quantum state transfer and long-term quantum memory.

Findings

Switchable coupling controlled by external magnetic flux

Efficient transfer of superposition states between qubits

Potential for long-lived quantum memory at optimal points

Abstract

We propose a hybrid quantum circuit with both charge and flux qubits connected to a large Josephson junction that gives rise to an effective inter-qubit coupling controlled by the external magnetic flux. This switchable inter-qubit coupling can be used to transfer back and forth an arbitrary superposition state between the charge qubit and the flux qubit working at the optimal point. The proposed hybrid circuit provides a promising quantum memory because the flux qubit at the optimal point can store the tranferred quantum state for a relatively long time.