Freiburg 2024 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 42: Long-range Interactions
Q 42.7: Talk
Thursday, March 14, 2024, 12:45–13:00, HS 1015
Ab initio simulation of dipolar Bose gases with the complex Langevin algorithm — •Philipp Heinen1, Wyatt Kirkby1,2, Lauriane Chomaz2, and Thomas Gasenzer1 — 1Kirchhoff-Institut für Physik, Universität Heidelberg — 2Physikalisches Institut, Universität Heidelberg
Bose-Einstein condensates (BECs) of atoms with a strong magnetic moment in their ground state, e.g. Erbium or Dysprosium, feature long-range dipolar interactions. These give rise to several peculiar phenomena that are absent from purely contact interacting Bose gases, notably rotonic excitations, supersolidity and quantum droplets. What makes them interesting from the theoretical point of view is that mean-field descriptions based on the Gross-Pitaevskii equation (GPE) fail to predict such states of matter and the effect of quantum fluctuations must be included. This can be done by adding an additional term to the GPE based on the perturbative Lee-Huang-Yang (LHY) correction or by performing ab initio path integral Monte Carlo (PIMC) simulations. The latter are, however, limited to several hundred atoms due to the high computational cost of the method, far below experimentally realistic particle numbers. An alternative is the equally fully exact complex Langevin (CL) algorithm whose computational cost is independent of the particle number and is thus suitable for simulating actual experimental settings from first principles. We will present the results of such simulations on both sides of the superfluid-supersolid transition of a dipolar BEC.
Keywords: Dipolar BEC; Complex Langevin; Supersolidity; Ab initio simulation