Spin cat states in a ferromagnetic insulator

TL;DR

This paper proposes a method to generate macroscopic magnetization superposition states, called spin cat states, in a ferromagnetic insulator coupled to a microwave cavity, advancing quantum state control in magnetic systems.

Contribution

It introduces a scheme to produce magnetization cat states in a ferromagnet-cavity system using anisotropic quantum fluctuations and measurement-induced collapse.

Findings

Feasible creation of a two-component cat state separated by ~5ħ.

Use of ground state anisotropic fluctuations as a resource.

Potential experimental setups discussed for realization.

Abstract

Generating non-classical states in macroscopic systems is a long standing challenge. A promising platform in the context of this quest are novel hybrid systems based on magnetic dielectrics, where photons can couple strongly and coherently to magnetic excitations, although a non-classical state therein is yet to be observed. We propose a scheme to generate a magnetization cat state, i.e. a quantum superposition of two distinct magnetization directions, using a conventional setup of a macroscopic ferromagnet in a microwave cavity. Our scheme uses the ground state of an ellipsoid shaped magnet, which displays anisotropic quantum fluctuations akin to a squeezed vacuum. The magnetization collapses to a cat state by either a single-photon or a parity measurement of the microwave cavity state. We find that a cat state with two components separated by $\sim5\hbar$ is feasible and briefly discuss potential experimental setups that can achieve it.