Related papers: Finite-temperature topological phase transitions of spin-$j$ systems in Uhlmann processes: General formalism and experimental protocols

Finite-temperature topological phase transitions of spin-$j$ systems in Uhlmann processes: General formalism and experimental protocols

URL: http://arxiv.org/abs/2103.15340v2
Date: Mon, 31 May 2021 17:21:11 GMT
Title: Finite-temperature topological phase transitions of spin-$j$ systems in Uhlmann processes: General formalism and experimental protocols
Authors: Xu-Yang Hou, Hao Guo, Chih-Chun Chien
Abstract summary: We analyze an ideal spin-j quantum paramagnet in a magnetic field undergoing an Uhlmann process. A quantized jump of the Uhlmann phase signifies a topological quantum phase transition (TQPT) of the underlying process. The exact results of j=1/2 and j=1 systems show topological regimes that only survive at finite temperatures but not at zero temperature.
Score: 2.6514968639939296
License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
Abstract: The Uhlmann process is built on the density matrix of a mixed quantum state and offers a way to characterize topological properties at finite temperatures. We analyze an ideal spin-j quantum paramagnet in a magnetic field undergoing an Uhlmann process and derive general formulae of the Uhlmann phase and Loschmidt amplitude for arbitrary j as the system traverses a great circle in the parameter space. A quantized jump of the Uhlmann phase signifies a topological quantum phase transition (TQPT) of the underlying process, which is accompanied by a zero of the Loschmidt amplitude. The exact results of j=1/2 and j=1 systems show topological regimes that only survive at finite temperatures but not at zero temperature, and the number of TQPTs is associated with the winding number in the parameter space. Our results pave the way for future studies on finite-temperature topological properties, and possible experimental protocols and implications for atomic simulators and digital simulations are discussed.

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