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Kubo Formula for Non-Hermitian Systems and Tachyon Optical Conductivity
Doru Sticlet1, Balázs Dóra2, Cătălin Paşcu Moca3,4
1National Institute for R&D of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca, Romania.
Physical Review Letters
|January 21, 2022
Summary
We developed a general theory for linear response in non-Hermitian systems, revealing finite DC conductivity and satisfied optical sum rules for tachyons. This advances understanding of non-Hermitian quantum dynamics.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
- Theoretical Physics
Background:
- Linear response theory is crucial for understanding quantum and classical systems.
- Non-Hermitian systems with nonunitary dynamics present unique theoretical challenges.
Purpose of the Study:
- To develop a general theory for linear response in non-Hermitian systems.
- To derive a modified Kubo formula applicable to arbitrary systems and perturbations.
- To investigate the dynamical response of a specific non-Hermitian Dirac model.
Main Methods:
- Development of a generalized linear response theory.
- Derivation of a modified Kubo formula for generalized susceptibility.
- Analysis of a one-dimensional non-Hermitian Dirac model with a time-dependent electric field.
Main Results:
- A modified Kubo formula was derived for non-Hermitian systems.
- The dynamical response of a non-Hermitian Dirac model was evaluated.
- Finite DC conductivity and exact satisfaction of the optical sum rule were found for tachyons.
Conclusions:
- The study highlights peculiar properties of the Kubo formula in non-Hermitian systems.
- Results are applicable to diverse physical settings involving non-Hermitian dynamics.
- The findings advance the theoretical framework for studying complex quantum systems.
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