Long-range and selective coupler for superconducting flux qubits

TL;DR

This paper introduces a novel tunable coupling scheme for superconducting flux qubits using a Josephson junction resonator and microwave irradiation, enabling remote qubit entanglement and scalable quantum gates.

Contribution

It presents a new method for long-range, selective qubit coupling via a tunable resonator controlled by bias current, advancing quantum gate construction.

Findings

Achieved entanglement between distant qubits via microwave-induced two-photon Rabi oscillation.

Demonstrated the use of a large-scale resonator for remote qubit interaction.

Proposed a scalable approach for quantum gate implementation in superconducting qubits.

Abstract

We propose a qubit-qubit coupling scheme for superconducting flux quantum bits (qubits), where a quantized Josephson junction resonator and microwave irradiation are utilized. The junction is used as a tunable inductance controlled by changing the bias current flowing through the junction, and thus the circuit works as a tunable resonator. This enables us to make any qubits interact with the resonator. Entanglement between two of many qubits whose level splittings satisfy some conditions, is formed by microwave irradiation causing a two-photon Rabi oscillation. Since the size of the resonator can be as large as sub-millimeters and qubits interact with it via mutual inductance, our scheme makes it possible to construct a quantum gate involving remote qubits