Strong coupling and active cooling in a finite temperature hybrid atom-cavity system

TL;DR

This paper demonstrates that a hybrid atom-cavity system can exhibit strong quantum coupling and enable cooling of thermal microwave modes at finite temperatures, facilitating observation of quantum phenomena at higher temperatures like 4 K.

Contribution

It introduces a hybrid system of a superconducting cavity and multi-level Rydberg atom that achieves strong coupling and cooling at finite temperatures, which was not previously demonstrated.

Findings

Quantum nature observable at 4 K in hybrid system

Effective cooling of thermal microwave modes achieved

Potential for long-range superconducting qubit coupling

Abstract

For a standard two-level atom coupled to the quantized field of a resonant cavity, finite temperature effects lead to thermal occupation of the cavity modes that obfuscates measurement of the quantum nature of the atom-light interaction. In this paper we demonstrate that using a hybrid system of a superconducting cavity coupled to a multi-level Rydberg atom it is possible to observe the quantum nature of strong coupling even at finite temperatures, and to exploit this coupling to permit cooling of the thermal microwave mode towards the ground-state, enabling observation of coherent vacuum Rabi oscillations even at 4~K for realistic experimental parameters. Cooling for multiple atoms is also explored, showing maximal cooling for small samples, making this a viable approach to cavity cooling with potential applications in long-range coupling of superconducting qubits via thermal waveguides.