Precise Feshbach resonance spectroscopy using tight anharmonic traps

TL;DR

This paper demonstrates that using tight anharmonic traps like optical lattices or tweezers allows for highly precise Feshbach resonance spectroscopy, providing detailed atomic information crucial for ultracold atom research.

Contribution

It introduces a method for precise Feshbach resonance characterization using double well traps, surpassing previous resolution limits in complex atomic species.

Findings

Resolved resonance positions and widths with high accuracy

Determined resonance pole strengths for atomic structure insights

Enhanced spectroscopic resolution over traditional methods

Abstract

Feshbach resonances are among the essential control tools used in ultracold atom experiments. However, for complex atomic species the theoretical characterization of resonances becomes challenging. For closely spaced resonances, the measurement of three-body losses does not provide sufficient resolution to discriminate them. For this reason, resonance spectroscopy of trapped isolated atoms is becoming the state of the art. Here we show that trapping the atoms in a double well potential such as an optical lattice or a pair of optical tweezers enables precise characterization of not only the resonance position and width, but also its pole strength, giving valuable information about the atomic structure relevant for subsequent many-body studies.