4.7 Article

Locality of Temperature

期刊

PHYSICAL REVIEW X
卷 4, 期 3, 页码 -

出版社

AMER PHYSICAL SOC
DOI: 10.1103/PhysRevX.4.031019

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资金

  1. Studienstiftung des Deutschen Volkes
  2. Alexander von Humboldt Stiftung
  3. EU
  4. ERC

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This work is concerned with thermal quantum states of Hamiltonians on spin- and fermionic-lattice systems with short-range interactions. We provide results leading to a local definition of temperature, thereby extending the notion of intensivity of temperature to interacting quantum models. More precisely, we derive a perturbation formula for thermal states. The influence of the perturbation is exactly given in terms of a generalized covariance. For this covariance, we prove exponential clustering of correlations above a universal critical temperature that upper bounds physical critical temperatures such as the Curie temperature. As a corollary, we obtain that above the critical temperature, thermal states are stable against distant Hamiltonian perturbations. Moreover, our results imply that above the critical temperature, local expectation values can be approximated efficiently in the error and the system size.

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