Pairing Mechanism at Finite Temperatures in Bosonic Systems |
| A. Krzywicka, T.P. Polak
Adam Mickiewicz University of Poznań, Faculty of Physics, Umultowska 85, 61-614 Poznań, Poland |
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| The pure Bose-Hubbard model, a staple of optical lattice-related research that describes bosonic condensation, is examined at finite temperatures. Advanced analytical methods are used, most importantly path integrals and quantum rotors. A first-order trace approximation is commonly applied while integrating over bosonic fields to obtain a phase-only model. Here, a second-order trace approximation is considered instead. This extension leads to an effective phase model with two types of superfluid, i.e., standard Bose-Einstein condensation and additional temperature-driven bosonic pair condensation. This effective model is further treated with a self-consistent harmonic approximation in order to compare the two superfluids. This analysis shows that the pairing mechanism strengthens the condensate phase at finite temperatures. |
DOI:10.12693/APhysPolA.143.157 topics: Bose-Hubbard model, path integral, phase Hamiltonian, phase transition |