Quantum criticality of the sub-Ohmic spin-boson model within displaced Fock states

2014/10/04 by He, Shu, Duan, Liwei, Chen, Qing-Hu
#FOS: Physical sciences #Quantum Physics (quant-ph)

paper · doi:10.48550/arxiv.1410.0999

Abstract

The spin-boson model is analytically studied using displaced Fock states (DFS) without discretization of the continuum bath. In the orthogonal displaced Fock basis, the ground-state wavefunction can be systematically improved in a controllable way. Interestingly, the zeroth-order DFS reproduces exactly the well known Silbey-Harris results. In the framework of the second-order DFS, the magnetization and the entanglement entropy are exactly calculated. It is found that the magnetic critical exponent β is converged to 0.5 in the whole sub-Ohmic bath regime 0

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