3D Cavity quantum electrodynamics with a rare-earth spin ensemble

TL;DR

This paper demonstrates the coherent integration of an Er:YSO spin ensemble with a 3D cavity resonator, showing potential for quantum memory and microwave-optical interfaces in quantum computing.

Contribution

It introduces a novel 3D cavity QED setup with rare-earth spins, achieving strong collective coupling and exploring anisotropic interactions.

Findings

Collective coupling strength of 21 MHz achieved.

Demonstrated anisotropic coupling in 3D cavity.

Potential for microwave quantum memories and interfaces.

Abstract

We present cavity QED experiments with an Er:YSO crystal magnetically coupled to a 3D cylindrical sapphire loaded copper resonator. Such waveguide cavities are promising for the realization of a superconducting quantum processor. Here, we demonstrate the coherent integration of a rare-earth spin ensemble with the 3D architecture. The collective coupling strength of the Er$^{3+}$ spins to the 3D cavity is 21 MHz. The cylindrical sapphire loaded resonator allowed us to explore the anisotropic collective coupling between the rare-earth doped crystal and the cavity. This work shows the potential of spin doped solids in 3D quantum circuits for application as microwave quantum memories as well as for prospective microwave to optical interfaces.