Bonn 2025 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 11: Poster – Cold Atoms and Molecules, Matter Waves (joint session Q/A/MO)

A 11.57: Poster

Dienstag, 11. März 2025, 14:00–16:00, Tent

Exploring the superfluid phase diagram for imbalanced Fermi gases in 2D — •René Henke, Cesar R. Cabrera, Moritz von Usslar, Artak Mkrtchyan, and Henning Moritz — Institut für Quantenphysik, Universität Hamburg

In Fermionic superfluids, condensation occurs through the pairing of fermions with opposite momenta and spin. This process is disturbed by introducing a spin imbalance, which leads to a mismatch between the respective Fermi surfaces. The result is a complex phase diagram including different phases, such as phase separation between a balanced superfluid and free fermions, as well as more exotic phases like the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, where the pairs carry non-zero momentum. As of now, the phase diagram of imbalanced Fermi gases in two dimensions remains largely unexplored.

In this poster, we present our results on spin-imbalanced homogeneous Fermi gases in two dimensions. Using lattice modulation spectroscopy, we excite a collective mode associated to the superfluid order parameter of the system. Our results show how this collective mode vanishes at a critical polarization and interaction strength, providing a step towards understanding exotic pairing in low dimensions.

Keywords: ultracold Fermi gases; superfluids; low dimensional systems; spin imbalance