Thermodynamics of a dilute Bose gas: A path-integral Monte Carlo study

We present precise path-integral Monte Carlo results for the thermodynamics of a homogeneous dilute Bose gas. Pressure and energy are calculated as function temperature both below above Bose-Einstein transition. Specifically, we address interaction effects, focusing on deviations from ideal-gas law in thermodynamic limit. also calculate isothermal compressibility contact parameter, which provide clear signature role played by interactions. In particular, obtain indications discontinuity at transition point. To gain physical insight, numerical systematically compared with predictions first-order Hartree-Fock second-order Popov theories, giving an approximate description gas thermodynamics. The comparison shows extension critical region around point, where inaccuracies perturbative expansions more pronounced.