Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 31: Ultracold Matter IV – Bosons, Rydberg Systems, and Others (joint session Q/A)

Q 31.4: Vortrag

Mittwoch, 4. März 2026, 15:15–15:30, P 2

Functional approach to quantum depletion in the thermodynamic limit — •Jin Han¹, Thomas Gasenzer^1,2, and Jan M. Pawlowski² — ¹Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227 — ²Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16

We present a study of repulsive U(1)-bosonic gas with large scattering length. The effective action under consideration respects Galilean invariance and provides proper description for superfluidity and neutral superconductivity at an energy regime far below the mass gap of a solitonic excitation. The resolution of this system requires non-perturbative methods, and we apply the functional renormalisation group, formulated for quantum systems at vanishing temperature and finite chemical potential. In particular, we compute the three-momentum scaling of the atomic density over Bose-Einstein condensate and explain its connection with the Lee-Huang-Yang correction characterizing the two-body Tan's contact. To conclude, we promote the idea of anomalous quantum depletion.

Keywords: Cold Atoms; Superfluidity; Renormalisation Group; Quantum Dissipation