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Updated: May 18, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
Noncanonical statistics of a spin-boson model: theory and exact Monte Carlo simulations
Chee Kong Lee1, Jianshu Cao, Jiangbin Gong
1Centre for Quantum Technologies, National University of Singapore, 117543, Singapore.
Abstract:
Equilibrium canonical distribution in statistical mechanics assumes weak system-bath coupling (SBC). In real physical situations this assumption can be invalid, and equilibrium quantum statistics of the system may be noncanonical. By exploiting both polaron transformation and perturbation theory in a spin-boson model, an analytical treatment is advocated to study noncanonical statistics of a two-level system at arbitrary temperature and for arbitrary SBC strength, yielding theoretical results in agreement with exact Monte Carlo simulations. In particular, the eigen-representation of system's reduced density matrix is used to quantify noncanonical statistics as well as the quantumness of the open system. For example, it is found that irrespective of SBC strength, noncanonical statistics enhances as temperature decreases but vanishes at high temperature.
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