2025/06/16 by M. Bulakhov, Bulakhov, M., A. S. Peletminskii +1
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Advanced NMR Techniques and Applications #Atomic and Subatomic Physics Research #FOS: Physical sciences #Quantum Gases (cond-mat.quant-gas)
paper · pdf · doi:10.48550/arxiv.2506.13413
openalex publication_date 2025/06/16 · openalex created_date 2025/10/13 · openalex updated_date 2026/07/28
We investigate the thermodynamic properties of an interacting Bose gas with a condensate within the energy-functional formulation of the Hartree-Fock-Bogoliubov (HFB) approach. For a contact interaction, we derive a self-consistent solution to the HFB equations that intrinsically eliminates divergence. This solution characterizes the equilibrium state featuring a condensate of correlated pairs of particles. We analyze the temperature dependence of key thermodynamic quantities such as condensate density, chemical potential, entropy, pressure, specific heat capacity at constant volume, and isothermal compressibility and compare them with predictions from the Popov approximation (PA). We predict that the transition temperature shifts to higher values due interactions, with the HFB approach yielding a larger shift than the PA. Analysis of the compressibility indicates that a pure pair condensate is unstable, and the stable equilibrium corresponds to only a mixture of single-particle and pair condensates.