Thermodynamics and renormalized quasiparticles in the vicinity of the dilute Bose gas quantum critical point in two dimensions

Article

关键词: CONTINUOUS SYMMETRY GROUP;    LONG-RANGE ORDER;    2-DIMENSIONAL SYSTEMS;    DESTRUCTION;    TRANSITION;   

DOI  :  10.1103/PhysRevB.95.024414

来源: SCIE

【 摘 要 】

We use the functional renormalization group (FRG) to derive analytical expressions for thermodynamic observables (density, pressure, entropy, and compressibility) as well as for single-particle properties (wave-function renormalization and effective mass) of interacting bosons in two dimensions as a function of temperature T and chemical potential mu. We focus on the quantum disordered and the quantum critical regime close to the dilute Bose gas quantum critical point. Our approach is based on a truncated vertex expansion of the hierarchy of FRG flow equations and the decoupling of the two-body contact interaction in the particle-particle channel using a suitable Hubbard-Stratonovich transformation. Our analytic FRGresults extend previous analytical renormalization-group calculations for thermodynamic observables at mu = 0 to finite values of mu. To confirm the validity of our FRG approach, we have also performed quantum Monte Carlo simulations to obtain the magnetization, susceptibility, and correlation length of the two-dimensional spin-1/2 quantum XY model with coupling J in a regime where its quantum critical behavior is controlled by the dilute Bose gas quantum critical point. We find that our analytical results describe the Monte Carlo data for mu <= 0 rather accurately up to relatively high temperatures T less than or similar to 0.1J.

【 授权许可】

Free