Optically trapped Feshbach molecules of fermionic $^{161}$Dy and $^{40}$K: Role of light-induced and collisional losses

TL;DR

This study investigates decay mechanisms of ultracold DyK dimers in optical traps, highlighting the influence of trap light and collisions, and demonstrating Pauli suppression of collisional losses near a Feshbach resonance.

Contribution

It provides experimental insights into loss processes of fermionic DyK dimers in various optical wavelengths and demonstrates Pauli suppression of collisional losses.

Findings

Trap-light-induced losses dominate except near 2000 nm.

Minimal light-induced losses observed around 1550 nm.

Pauli suppression reduces collisional losses by about an order of magnitude.

Abstract

We study the decay of a dense, ultracold sample of weakly bound DyK dimers stored in an optical dipole trap. Our bosonic dimers are composed of the fermionic isotopes $^{161}$Dy and $^{40}$K, which is of particular interest for experiments related to pairing and superfluidity in fermionic systems with mass imbalance. We have realized dipole traps with near-infrared laser light in four different wavelength regions between 1050 and 2002 nm. We have identified trap-light-induced processes as the overall dominant source of losses, except for wavelengths around 2000 nm, where light-induced losses appeared to be much weaker. In a trap near 1550 nm, we found a plateau of minimal light-induced losses, and by carefully tuning the wavelength, we reached conditions where losses from inelastic collisions between the trapped dimers became observable. For very weakly bound dimers close to the center of a magnetically tuned Feshbach resonance, we demonstrate the Pauli suppression of collisional losses by about an order of magnitude.