Breaking and trapping Cooper pairs by Rydberg-molecule spectroscopy in atomic Fermi superfluids

TL;DR

This paper introduces a spectroscopic method to observe the breaking and trapping of Cooper pairs in an atomic Fermi superfluid using Rydberg molecules, revealing insights into pairing mechanisms across the BCS-BEC crossover.

Contribution

It proposes a novel spectroscopic technique involving Rydberg molecules to probe Cooper pair dynamics and size in Fermi superfluids, bridging atomic physics and many-body quantum phenomena.

Findings

Detection of diatomic and triatomic Rydberg molecules across the BCS-BEC crossover.

Estimation of Cooper-pair size through Rydberg molecule spectroscopy.

Identification of many-body pairing effects via Rydberg molecule binding energies.

Abstract

We propose a spectroscopic probe of the breaking and localization of Cooper pairs in an atomic Fermi superfluid interacting with a Rydberg impurity. This is achieved by monitoring the formation of diatomic and triatomic ultralong-range molecular species in the superfluid across the BCS - Bose Einstein condensation (BEC) crossover. The triatomic Rydberg molecule in the BEC regime heralds the trapping of a tightly-bound Cooper pair, reminiscent of pion capture in nuclear matter, while the breaking of a Cooper pair on the BCS side by a diatomic Rydberg molecule is evocative of binary-star tidal disruption by a black hole. Spectroscopy of the Fermi superfluid and Rydberg molecules allows for an estimation of the Cooper-pair size while the Rydberg molecule binding energies discern many-body pairing effects.