Erlangen 2022 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 26: Quantum Gases (Fermions)
Q 26.5: Vortrag
Mittwoch, 16. März 2022, 11:30–11:45, Q-H10
Emergence of a quantum phase transition in a few-fermion system — •Keerthan Subramanian1, Luca Bayha1, Marvin Holten1, Ralf Klemt1, Johannes Bjerlin2, Stephanie Riemann2, Georg Bruun3, Philipp Preiss1, and Selim Jochim1 — 1Physikaliches Insitut, Universität Heidelberg — 2Lund University — 3Aarhus University
Phase transitions are collective macroscopic transformations that arise in many-body systems due to competing energy scales. In this talk we try to address the minimum instance where precursors of such a phase transition can be observed for as little as 6 and 12 particles.
We deterministically prepare low entropy samples of closed-shell fermionic 6Li atoms in a 2D harmonic oscillator potential. With the ability to control interactions with a Feshbach resonance, this model system is used to explore competing energy scales. The collective modes in such a system are probed with interaction modulation spectroscopy which reveals that the lowest monopole mode(s) show a non-monotonic behavior reminiscent of the Normal-Superfluid transition in the many-body limit and the associated Higgs mode. Observation that this mode(s) consists mainly of pair excitations and features an asymptotic gap closing with increasing particle number provide evidence in favor of this association to the many-body limit. The trapping potential introduces a single particle gap in the system which leads to a long lived Higgs mode precursor which is demonstrated.
Subsequent experiments on the microscopy of such and spin-imbalanced systems are alluded to.