SAMOP 2023 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 33: Quantum Gases: Bosons IV

Q 33.2: Talk

Wednesday, March 8, 2023, 14:45–15:00, A320

Bose-Einstein condensation for hard-core bosons: Universal upper bound and Bogoliubov theory — •Martina Jung, Sophie Brass, Julia Liebert, Sebastian Paeckel, and Christian Schilling — Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München

Hard-core bosons (HCBs), subjected to an artificial Pauli principle with respect to the lattice site basis, are not only of broad physical relevance due to their close relation to Spin-1/2 operators, but their theoretical description has recently revealed some intriguing conceptual features: the mixed commutation relations of HCB creation and annihilation operators give rise to a universal upper bound on the number of HCBs that can condense in the maximally delocalized state.

In this talk, we explain when and how this universal bound on the maximally possible degree of condensation - given by f= 1−ν, where ν is the filling factor - is saturated and dictates the physical behaviour of HCBs. In particular, we show by exact numerical means that this novel exclusion principle lies at the heart of the quantum phase transition in the one-dimensional lattice gas model. Based on this observation we then propose and work out a Bogoliubov theory specifically for HCBs in the regime of almost maximal condensation f ≈ 1−ν.