Coupling Josephson qubits via a current-biased information bus

TL;DR

This paper proposes a method to couple Josephson qubits indirectly through a controllable current-biased Josephson junction acting as an oscillator, enabling quantum logic operations and tests of Bell's inequality.

Contribution

It introduces a tunable coupling scheme for Josephson qubits via an information bus, facilitating entanglement and quantum operations without direct qubit interaction.

Findings

Effective qubit coupling via a current-biased junction

Controlled entanglement generation for quantum logic

Potential for testing Bell's inequality experimentally

Abstract

Josephson qubits without direct interaction can be effectively coupled by sequentially connecting them to an information bus: a current-biased large Josephson junction treated as an oscillator with adjustable frequency. The coupling between any qubit and the bus can be controlled by modulating the magnetic flux applied to that qubit. This tunable and selective coupling provides two-qubit entangled states for implementing elementary quantum logic operations, and for experimentally testing Bell's inequality.