Probing phase transitions in non-Hermitian systems with multiple quantum coherences

Diego Paiva Pires and Tommaso Macrì
Phys. Rev. B 104, 155141 – Published 25 October 2021

Abstract

Understanding the interplay between quantum coherence and non-Hermitian features would enable the devising of quantum technologies based on dissipative systems. In turn, quantum coherence can be characterized in terms of the language of multiple quantum coherences (MQCs) originally developed in solid-state nuclear magnetic resonance (NMR), nowadays applied to the detection of quantum chaos and to the study of criticality in many-body quantum systems. Here, we show the usefulness of MQCs for probing equilibrium phase transitions in non-Hermitian systems. To do so, we investigate the connection of quantum coherences and critical points for several paradigmatic non-Hermitian Hamiltonians. For a non-Hermitian two-level system, MQCs witness the parity-symmetry-breaking phase transition from the unbroken to the broken phase. Furthermore, for the non-Hermitian transverse field Ising model, MQCs capture the Yang-Lee phase transition in which the ground state energy acquires a nonzero imaginary component. For the disordered Hatano-Nelson (HN) model with periodic boundary conditions, MQCs testify the emergence of mobility edges in the spectrum of this model. In addition, MQCs signal the topological phase transition exhibited by the complex energy spectra of the disorder-free HN model. Finally, we comment on experimentally probing phase transitions in NMR systems, realizing non-Hermitian Hamiltonians. Our results have applications to non-Hermitian quantum sensing, quantum thermodynamics, and in the study of the non-Hermitian skin effect.

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  • Received 8 September 2021
  • Revised 5 October 2021
  • Accepted 13 October 2021

DOI:https://doi.org/10.1103/PhysRevB.104.155141

©2021 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyGeneral PhysicsCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Diego Paiva Pires1,* and Tommaso Macrì2,3

  • 1Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65080-805 São Luís, Maranhão, Brazil
  • 2Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, Rio Grande do Norte, Brazil
  • 3International Institute of Physics, Federal University of Rio Grande do Norte, Campus Universitário, Lagoa Nova, 59078-970 Natal, Rio Grande do Norte, Brazil

  • *diegopaivapires@gmail.com

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Issue

Vol. 104, Iss. 15 — 15 October 2021

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