Orbital Feshbach Resonance in Alkali-Earth Atoms

TL;DR

This paper proposes a novel orbital Feshbach resonance mechanism in alkali-earth atoms, enabling control of interactions in systems like ${}^{173}$Yb, with implications for superfluidity and quantum simulation.

Contribution

It introduces a new orbital Feshbach resonance mechanism based on inter-orbital spin exchange and orbital-dependent g-factors, expanding control over atomic interactions.

Findings

Resonance accessible in ${}^{173}$Yb system.

Distinct BCS-BEC crossover behavior with two pairing order parameters.

Orbital degrees of freedom mimic electron spin in magnetic Feshbach resonance.

Abstract

For a mixture of alkali-earth atomic gas in the long-lived excited state ${}^3P_0$ and ground state ${}^1S_0$, in addition to nuclear spin, another "orbital" index is introduced to distinguish these two internal states. In this letter we propose a mechanism to induce Feshbach resonance between two atoms with different orbital and nuclear spin quantum numbers. Two essential ingredients are inter-orbital spin-exchanging scattering and orbital dependence of the Land\'e g-factors. Here the orbital degrees of freedom plays similar role as electron spin degree of freedom in magnetic Feshbach resonance in alkali-metal atoms. This resonance is particularly accessible for ${}^{173}$Yb system. The BCS-BEC crossover in this system requires two fermion pairing order parameters, and displays significant difference comparing to that in alkali-metal system.