New Insights into Persistent Currents with Non-Hermitian Quantum Theory

Recent research published in Physical Review Letters introduces a novel approach to understanding persistent currents, which are currents that flow continuously without the need for external power sources. The paper titled "Non-Hermitian Fermi-Dirac Distribution in Persistent Current Transport" by Pei-Xin Shen, Zhide Lu, Jose L. Lado, and Mircea Trif explores the implications of non-Hermitian quantum Hamiltonians on these currents.

The authors extend existing theories to incorporate dissipation, a factor often overlooked in traditional models. They utilize Green's function formalism to present a non-Hermitian Fermi-Dirac distribution, leading to an analytical expression for persistent current that is based solely on the complex spectrum of the system. This approach is significant as it allows for the analysis of persistent currents in two specific models: a phase-biased superconducting-normal-superconducting junction and a normal ring influenced by magnetic flux.

One of the key findings is that the persistent currents in these systems do not exhibit anomalies at any emergent exceptional points, which are critical points in the parameter space of the system. Instead, the signatures of these exceptional points are only observable in the current susceptibility. The authors validate their theoretical predictions through exact diagonalization and extend their analysis to consider finite temperatures and interaction effects.

This research not only enhances the theoretical framework surrounding persistent currents but also opens avenues for future studies on non-Hermitian systems, potentially impacting the development of quantum technologies and materials science. The full paper can be accessed via arXiv under the identifier arXiv:2403.09569.