Mainz 2026 – scientific programme
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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: Talk
Wednesday, March 4, 2026, 15:15–15:30, P 2
Functional approach to quantum depletion in the thermodynamic limit — •Jin Han1, Thomas Gasenzer1,2, 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