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Spectroscopy and complex-time correlations using minimally entangled typical thermal states

Zhenjiu Wang1,2,3,*, Paul McClarty3,4, Dobromila Dankova3, Andreas Honecker5, and Alexander Wietek3,†

  • *Contact author: wangzj@lzu.edu.cn
  • †Contact author: awietek@pks.mpg.de
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Phys. Rev. B 113, 024406 – Published 5 January, 2026

DOI: https://doi.org/10.1103/fc58-w1rr

Abstract

Tensor network states have enjoyed great success in capturing aspects of strong correlation physics. However, obtaining dynamical correlators at nonzero temperatures is generically hard even using these methods. Here, we introduce a practical approach to computing such correlators using minimally entangled typical thermal states (METTS). While our primary method directly computes dynamical correlators of physical operators in real time, we propose extensions where correlations are evaluated in the complex-time plane. The imaginary time component bounds the rate of entanglement growth and strongly alleviates the computational difficulty allowing the study of larger system sizes. To extract the physical correlators, one must take the limit of purely real-time evolution. We present two routes for obtaining this information: (i) via an analytic correlation function in complex time combined with a stochastic analytic continuation method to obtain the real-time limit and (ii) a Hermitian correlation function that asymptotically captures the desired correlation function quantitatively. We show that these numerical techniques capture the finite-temperature dynamics of the Shastry-Sutherland model—a model of interacting spins one-half in two spatial dimensions.

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See Also

Anomalous thermal broadening in the Shastry-Sutherland model and SrCu2(BO3)2

Zhenjiu Wang, Paul McClarty, Dobromila Dankova, Andreas Honecker, and Alexander Wietek
Phys. Rev. B 113, L041104 (2026)

Article Text

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Phys. Rev. B 113, 024406– Published 5 January, 2026
  • Received 18 June 2024
  • Revised 19 September 2025
  • Accepted 22 September 2025
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