Controlling nuclear spin exchange via optical Feshbach resonances in ${}^{171}$Yb

TL;DR

This paper demonstrates how optical Feshbach resonances can be used to control nuclear spin exchange in ultracold ${}^{171}$Yb atoms, enabling high-fidelity quantum gate operations.

Contribution

It introduces a method to optically manipulate nuclear spin exchange in ultracold Ytterbium atoms using Feshbach resonances, with detailed calculations of scattering properties.

Findings

Achieves ~95% fidelity for a $\, ext{sqrt(SWAP)}$ quantum gate.

Shows significant modification of s-wave scattering phase shift via optical Feshbach resonance.

Provides a multichannel calculation framework for photoassociation resonances.

Abstract

Nuclear spin exchange occurs in ultracold collisions of fermionic alkaline-earth-like atoms due to a difference between s- and p-wave phase shifts. We study the use of an optical Feshbach resonance, excited on the ${}^1S_0 \to {}^3P_1$ intercombination line of ${}^{171}$Yb, to affect a large modification of the s-wave scattering phase shift, and thereby optically mediate nuclear exchange forces. We perform a full multichannel calculation of the photoassociation resonances and wave functions and from these calculate the real and imaginary parts of the scattering length. As a figure of merit of this interaction, we estimate the fidelity to implement a $\sqrt{SWAP}$ entangling quantum logic gate for two atoms trapped in the same well of an optical lattice. For moderate parameters one can achieve a gate fidelity of $\sim95% $ in a time of $\sim 50 \mu$s.