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Robust Nonequilibrium Edge Currents with and without Band Topology
Mark T Mitchison1, Ángel Rivas2,3, Miguel A Martin-Delgado2,3
1School of Physics, Trinity College Dublin, College Green, Dublin 2, D02 K8N4, Ireland.
Physical Review Letters
|April 8, 2022
Summary
This study reveals robust chiral edge currents in two-dimensional lattice systems, even without topological band effects. These currents flow against temperature gradients, demonstrating unique nonequilibrium phenomena in bosonic and fermionic systems.
Area of Science:
- Condensed Matter Physics
- Quantum Many-Body Systems
- Non-equilibrium Statistical Mechanics
Background:
- Understanding non-equilibrium phenomena in condensed matter systems is crucial for novel device applications.
- Topological phases of matter offer unique properties, but their behavior under non-equilibrium conditions requires further investigation.
- Lattice systems provide a tunable platform to explore fundamental physics under external influences like temperature gradients.
Purpose of the Study:
- To investigate nonequilibrium current distributions in two-dimensional bosonic and fermionic lattice systems subjected to thermal gradients.
- To characterize the role of topology and dissipative symmetries in the emergence of edge currents.
- To explore the robustness of these currents against environmental coupling and system imperfections.
Main Methods:
- Utilized a non-perturbative Green function approach to analyze the system's behavior.
- Studied a lattice model with broken time-reversal symmetry, encompassing both trivial and non-trivial topological phases.
- Imposed sharp temperature gradients using two thermal baths to create non-equilibrium conditions.
Main Results:
- Identified robust chiral edge currents in both bosonic and fermionic systems, unaffected by reservoirs or defects.
- Demonstrated that current robustness stems from topological effects at zero temperature and dissipative symmetries away from topology.
- Observed energy flowing against the temperature gradient due to chiral edge currents, without external work.
Conclusions:
- Chiral edge currents in these lattice systems exhibit remarkable robustness, persisting even in the absence of band topology.
- Dissipative symmetries play a key role in maintaining current chirality under non-equilibrium conditions.
- The findings highlight novel transport phenomena in driven quantum systems, with potential implications for thermodynamics and topological physics.
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