News Overview

The emergence of fermionic superfluidity and superconductivity is closely linked to the formation of Cooper pairs. These are strong correlations between pairs of electrons (or other fermions) with opposite spin and momentum localised at the Fermi surface in momentum space. Understanding the mechanism behind pair formation has so far been a challenge. In their new study published in Nature, the re­search team around Philipp Preiß and Selim Jochim have directly observed Cooper pairs in a mesoscopic two-dimensional Fermi gas. Using an advanced fluorescence imaging technique, they were able to extract spin- and single-atom-resolved momentum distributions with particle-detection fidelities comparable to those of quan­tum gas microscopes. With precise control over the interactions, particle number and potential landscape, they were able to establish observables that allow to identify different pairing mechanisms and to answer longstanding questions concerning not only such mesoscopic systems but also their connection to the macroscopic world.

Link: Re­search article by Holten et al. (2022) in Nature.