Universal Efimov Scaling in the Rabi-Coupled Few-Body Spectrum

TL;DR

This paper demonstrates that an external Rabi drive can universally shift and modulate the Efimov spectrum in a few-body quantum system, preserving its discrete scaling symmetry and enabling tunable three-body interactions.

Contribution

It reveals that Rabi coupling universally shifts the Efimov spectrum and preserves its scaling symmetry, offering a new way to control few-body quantum phenomena.

Findings

Efimov spectrum is centered around Rabi-shifted two-body resonance.

Rabi drive preserves the discrete scaling symmetry of Efimov trimers.

The three-body parameter is universally shifted, causing log-periodic modulation.

Abstract

We investigate the behavior of the Efimov effect -- a universal quantum few-body phenomenon -- in the presence of an external driving field. Specifically, we consider up to three bosonic atoms, such as $^{133}$Cs, interacting with a light atom, such as $^{6}$Li, where the latter has two internal spin states $\{\uparrow, \downarrow\}$ that are Rabi coupled. Assuming that only the spin-$\uparrow$ light atom interacts with the bosons, we find that the Rabi drive transposes the entire Efimov spectrum such that the Efimov trimers and tetramers are centered around the Rabi-shifted two-body scattering resonance. Crucially, we show that the Rabi drive preserves the trimers' discrete scaling symmetry, while universally shifting the Efimov three-body parameter, leading to a log-periodic modulation in the spectrum as the Rabi drive is varied. Our results suggest that Efimov physics can be conveniently explored using an applied driving field, opening up the prospect of an externally tunable three-body parameter.