Anisotropic rare-earth spin ensemble strongly coupled to a superconducting resonator

TL;DR

This paper demonstrates strong magnetic coupling between anisotropic Er3+ spins in Y2SiO5 crystals and a superconducting resonator, advancing hybrid quantum architectures for scalable quantum computing.

Contribution

It reports the first strong coupling of anisotropic rare-earth spins to a superconducting resonator in a cavity QED setup, with direct microwave detection of spin dynamics.

Findings

Achieved strong coupling in a hybrid quantum system

Detected electron spin resonance via microwave absorption

Demonstrated potential for scalable quantum computing architectures

Abstract

Interfacing photonic and solid-state qubits within a hybrid quantum architecture offers a promising route towards large scale distributed quantum computing. Ideal candidates for coherent qubit interconversion are optically active spins magnetically coupled to a superconducting resonator. We report on a cavity QED experiment with magnetically anisotropic Er3+:Y2SiO5 crystals and demonstrate strong coupling of rare-earth spins to a lumped element resonator. In addition, the electron spin resonance and relaxation dynamics of the erbium spins are detected via direct microwave absorption, without aid of a cavity.