-Symmetric Effective Model for Nonequilibrium Phase Transitions in a Dissipative Fermionic Mott Insulator Chain

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Non-Hermitian Physics

Background:

• Nonequilibrium phase transitions in open dissipative systems are often described by effective non-Hermitian Hamiltonians.
• These models exhibit parity-time (PT) symmetry, which is lost at the transition point.
• Microscopic foundations for these phenomenological models are currently lacking.

Purpose of the Study:

• To propose a microscopic mechanism for the PT-symmetric effective model in the context of a nonequilibrium Mott transition.
• To investigate the role of electron-phonon coupling and electric fields in driving these transitions.
• To analyze the implications for understanding re-entrant insulator behavior.

Main Methods:

• A microscopic model of a half-filled fermionic Hubbard chain subjected to an electric field and electron-phonon coupling is developed.
• Explicit expressions for the non-Hermitian parameter are derived in terms of system parameters.
• The model is analyzed to understand the conditions for PT symmetry and phase transitions.

Main Results:

• A microscopic mechanism leading to the PT-symmetric effective model is established.
• Explicit expressions for the non-Hermitian parameter are obtained, linking it to electron-phonon coupling and driving field.
• A re-entrant Mott insulator phase is predicted for specific phonon density of states.

Conclusions:

• The study provides a microscopic basis for phenomenological models of nonequilibrium phase transitions.
• The findings offer insights into the behavior of dissipative quantum systems under external driving.
• The prediction of re-entrant Mott insulator behavior highlights complex phase diagrams in driven quantum systems.