Laser Manipulation of Spin-Exchange Interaction Between Alkaline-Earth Atoms in $^1$S$_0$ and $^3$P$_2$ States

TL;DR

This paper proposes laser-based methods to control spin-exchange interactions in ultracold alkaline-earth atoms, enabling tunable quantum simulations with minimal heating effects, which was previously challenging due to the fixed nature of these interactions.

Contribution

The authors introduce three laser-driven techniques to tune spin-exchange interactions in alkaline-earth atoms, overcoming the limitations of magnetic Feshbach resonance.

Findings

Laser methods can induce Feshbach resonances with low heating.

AC-Stark shifts and Raman couplings achieve MHz-level control.

Heating rates are suppressed to Hz levels, enabling stable manipulation.

Abstract

Ultracold gases of fermionic alkaline-earth (like) atoms are hopeful candidates for the quantum simulation of many-body physics induced by magnetic impurities (e.g., the Kondo physics), because there are spin-exchange interactions (SEIs) between two atoms in the electronic ground ($^1$S$_0$) and metastable ($^3$P) state, respectively. Nevertheless, this SEI cannot be tuned via magnetic Feshbach resonance. In this work we propose three methods to control the SEI between one atom in the $^1$S$_0$ state and another atom in the $^3$P$_2$ states or $^3$P$_2$-$^3$P$_0$ dressed states, with one or two laser beams.These methods are based on the spin-dependent AC-Stark shifts of the $^3$P$_2$ states, or the $^3$P$_2$-$^3$P$_0$ Raman coupling. We show that due to the structure of alkaline-earth (like) atoms, the heating effects induced by the laser beams of our methods are very weak. For instance, for ultracold Yb atoms, AC-Stark-shift difference of variant spin states of the $^3$P$_2(F=3/2)$ level, or the strength of the $^3$P$_2$-$^3$P$_0$ Raman coupling, could be of the order of $(2\pi)$MHz, while the heating rate (photon scattering rate) is only of the order of Hz. As a result, the Feshbach resonances, with which one can efficiently control the SEI by changing the laser intensity, may be induced by the laser beams with low-enough heating rate, even if the scattering lengths of the bare inter-atomic interaction are so small that being comparable with the length scale associated with the van der Waals interaction.