Pairing in few-fermion systems with attractive interactions

TL;DR

This study investigates few-fermion systems with attractive interactions in quasi-one-dimensional traps, revealing pair correlations and odd-even effects through tunneling experiments, advancing understanding of few-body quantum phenomena.

Contribution

The paper provides experimental evidence of pairing and odd-even effects in ultracold fermionic systems with few particles, using tunneling dynamics as a probe.

Findings

Observation of pair correlations in even particle systems

Detection of strong odd-even effects in interaction energies

Deviations from single-particle tunneling behavior

Abstract

We have studied quasi one-dimensional few-particle systems consisting of one to six ultracold fermionic atoms in two different spin states with attractive interactions. We probe the system by deforming the trapping potential and by observing the tunneling of particles out of the trap. For even particle numbers we observe a tunneling behavior which deviates from uncorrelated single-particle tunneling indicating the existence of pair correlations in the system. From the tunneling timescales we infer the differences in interaction energies of systems with different number of particles which show a strong odd-even effect, similar to the one observed for neutron separation experiments in nuclei.