paper

Variational tensor network renormalization in imaginary time: Two-dimensional quantum compass model at finite temperature

arXiv:1512.07168 · doi:10.1103/PhysRevB.93.184410

Abstract

Progress in describing thermodynamic phase transitions in quantum systems is obtained by noticing that the Gibbs operator for a two-dimensional (2D) lattice system with a Hamiltonian can be represented by a three-dimensional tensor network, the third dimension being the imaginary time (inverse temperature) . Coarse-graining the network along results in a 2D projected entangled-pair operator (PEPO) with a finite bond dimension . The coarse-graining is performed by a tree tensor network of isometries. The isometries are optimized variationally --- taking into account full tensor environment --- to maximize the accuracy of the PEPO. The algorithm is applied to the isotropic quantum compass model on an infinite square lattice near a symmetry-breaking phase transition at finite temperature. From the linear susceptibility in the symmetric phase and the order parameter in the symmetry-broken phase the critical temperature is estimated at , where is the isotropic coupling constant between pseudospins.

12 pages, 15 figures, slightly revised after referees' reports

References in corpus (37)

Cited by in corpus (29)