Laser induced enhanced coupling between photons and squeezed magnons in antiferromagnets

TL;DR

This study explores how an external laser field can enhance photon-magnon coupling in antiferromagnets by modifying exchange interactions and inducing non-reciprocal magnon modes, leading to tunable quantum states.

Contribution

It introduces a method to control magnon properties and photon-magnon coupling strength in antiferromagnets using laser-induced effects, including synthetic Dzyaloshinskii-Moriya interaction.

Findings

Laser renormalizes exchange interactions in antiferromagnets.

Laser induces synthetic Dzyaloshinskii-Moriya interaction between second neighbors.

Photon-magnon coupling can be enhanced by an order of magnitude through laser tuning.

Abstract

In this paper we consider a honeycomb antiferromagnet subject to an external laser field. Obtaining a time-independent effective Hamiltonian, we find that the external laser renormalizes the exchange interaction between the in-plane components of the spin-operators, and induces a synthetic Dzyaloshinskii-Moria interaction (DMI) between second neighbors. The former allows the control of the magnon dispersion's bandwidth and the latter breaks time-reversal symmetry inducing non-reciprocity in momentum space. The eigen-excitations of the system correspond to squeezed magnons whose squeezing parameters depend on the properties of the laser. When studying how these spin excitations couple with cavity photons, we obtain a coupling strength which can be enhanced by an order of magnitude via careful tuning of the laser's intensity, when compared to the case where the laser is absent. The transmission plots through the cavity are presented, allowing the mapping of the magnons' dispersion relation.