Condensation temperature and magnetic phases of trapped coherently coupled Bose gases
Abstract
We investigate condensation and finite-temperature magnetic phase transitions in a coherently (Rabi) coupled Bose gas confined in a three-dimensional harmonic trap. For the noninteracting system, we derive analytical expressions for the critical temperature and condensate fraction using a semiclassical description of the single-particle spectrum and density of states. At fixed particle number, coherent coupling enhances the critical temperature relative to the uncoupled system, and this enhancement decreases with increasing particle number N. The finite-size correction, in contrast, lowers the transition temperature, with its effect diminishing for larger N. We then incorporate repulsive interactions within the Hartree--Fock--Bogoliubov--Popov framework to investigate the finite-temperature phase diagram in the temperature--Rabi coupling plane. The system undergoes successive transitions from a ferromagnetic to a paramagnetic condensate and, at higher temperature, to a thermal gas. The transition boundaries obtained from the vanishing of the condensate fraction show excellent agreement with the analytical Hartree-Fock predictions. We find that the interactions substantially suppress the variation in the condensation temperature with an increase in the coherent coupling.
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BibTeX
@misc{sunilkumar2026condensation,
title = {{Condensation temperature and magnetic phases of trapped coherently coupled Bose gases}},
author = {Sunilkumar V and Rajat and Sandeep Gautam and Arko Roy},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11779},
eprint = {2609.11779},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.11779},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Condensation temperature and magnetic phases of trapped coherently coupled Bose gases
AU - Sunilkumar V
AU - Rajat
AU - Sandeep Gautam
AU - Arko Roy
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.11779
UR - https://arxiv.org/abs/2609.11779
AB - We investigate condensation and finite-temperature magnetic phase transitions in a coherently (Rabi) coupled Bose gas confined in a three-dimensional harmonic trap. For the noninteracting system, we derive analytical expressions for the critical temperature and condensate fraction using a semiclassical description of the single-particle spectrum and density of states. At fixed particle number, coherent coupling enhances the critical temperature relative to the uncoupled system, and this enhancement decreases with increasing particle number N. The finite-size correction, in contrast, lowers the transition temperature, with its effect diminishing for larger N. We then incorporate repulsive interactions within the Hartree--Fock--Bogoliubov--Popov framework to investigate the finite-temperature phase diagram in the temperature--Rabi coupling plane. The system undergoes successive transitions from a ferromagnetic to a paramagnetic condensate and, at higher temperature, to a thermal gas. The transition boundaries obtained from the vanishing of the condensate fraction show excellent agreement with the analytical Hartree-Fock predictions. We find that the interactions substantially suppress the variation in the condensation temperature with an increase in the coherent coupling.
ER -