Tunable coupling between a superconducting resonator and an artificial atom

TL;DR

This paper presents a circuit QED system with a tunable coupling mechanism between an artificial atom and a superconducting resonator, enabling control from weak to ultrastrong coupling regimes for quantum applications.

Contribution

It introduces a novel tunable coupling design that maintains fixed cavity and atomic frequencies, with a detailed analysis of its control and noise sensitivity.

Findings

Coupling strength can be tuned from weak to ultrastrong regimes.

The system's sensitivity to external magnetic flux noise is analyzed.

Quantum perturbation theory accurately models the coupling behavior.

Abstract

Coherent manipulation of a quantum system is one of the main themes in current physics researches. In this work, we design a circuit QED system with a tunable coupling between an artificial atom and a superconducting resonator while keeping the cavity frequency and the atomic frequency invariant. By controlling the time dependence of the external magnetic flux, we show that it is possible to tune the interaction from the extremely weak coupling regime to the ultrastrong coupling one. Using the quantum perturbation theory, we obtain the coupling strength as a function of the external magnetic flux. In order to show its reliability in the fields of quantum simulation and quantum computing, we study its sensitivity to noises.