Circuit electromechanics with single photon strong coupling

TL;DR

This paper demonstrates that replacing a capacitor with a superconducting flux qubit in circuit electromechanics can achieve strong single-photon coupling, enabling exploration of quantum nonlinear effects.

Contribution

The authors propose a novel scheme using a superconducting flux qubit to enhance electromechanical coupling to the strong regime at the single photon level.

Findings

Achieved effective strong coupling with feasible experimental parameters.

Formed a three-wave mixing configuration among qubit and resonators.

Enabled potential study of quantum nonlinear effects in circuit electromechanics.

Abstract

In circuit electromechanics, the coupling strength is usually very small. Here, replacing the capacitor in circuit electromechanics by a superconducting flux qubit, we show that the coupling among the qubit and the two resonators can induce effective electromechanical coupling which can attain the strong coupling regime at the single photon level with feasible experimental parameters. We use dispersive couplings among two resonators and the qubit while the qubit is also driven by an external classical field. These couplings form a three-wave mixing configuration among the three elements where the qubit degree of freedom can be adiabatically eliminated, and thus results in the enhanced coupling between the two resonators. Therefore, our work constitutes the first step towards studying quantum nonlinear effect in circuit electromechanics.