External field control of collective spin excitations in an optical lattice of $^2\Sigma$ molecules

TL;DR

This paper demonstrates how external electric and magnetic fields can control collective spin excitations, specifically magnetic Frenkel excitons, in an optical lattice of $^2\Sigma$ molecules, enabling tunable and localized spin dynamics.

Contribution

It introduces a method to manipulate collective spin excitations in molecular lattices using external fields, including exciton formation, localization, and dynamic control.

Findings

Magnetic Frenkel excitons can be formed and tuned by external fields.

Vacancies in the lattice localize exciton states and affect their patterns.

External fields can control the speed of spin excitation transfer.

Abstract

We show that an ensemble of $^2\Sigma$ molecules in the rotationally ground state trapped on an optical lattice exhibits collective spin excitations that can be controlled by applying superimposed electric and magnetic fields. In particular, we show that the lowest energy excitation of the molecular ensemble at certain combinations of electric and magnetic fields leads to the formation of a magnetic Frenkel exciton. The exciton bandwidth can be tuned by varying the electric or magnetic fields. We show that the exciton states can be localized by creating vacancies in the optical lattice. The localization patterns of the magnetic exciton states are sensitive to the number and distribution of vacancies, which can be exploited for engineering many-body entangled spin states. We consider the dynamics of magnetic exciton wavepackets and show that the spin excitation transfer between molecules in an optical lattice can be accelerated or slowed down by tuning an external magnetic or electric field.