# Seeking Maxwell's Demon in a non-reciprocal quantum ring

## TL;DR

This paper investigates a non-reciprocal quantum ring with Rashba spin-orbit interaction, revealing unique electronic properties and demonstrating a nanoscale Maxwell's demon that sorts electrons by spin without external work.

## Contribution

It introduces a non-reciprocal quantum ring with distinct spin-dependent properties and demonstrates a Maxwell's demon-like mechanism at the nanoscale.

## Key findings

- Aharonov-Bohm oscillations are absent in the ring.
- Electrons are spatially separated by spin via magnetic field control.
- Different spin temperatures are observed in the two arms.

## Abstract

A non-reciprocal quantum ring, where one arm of the ring contains the Rashba spin-orbit interaction but not in the other arm, is found to posses very unique electronic properties. In this ring the Aharonov-Bohm oscillations are totally absent. That is because in a magnetic field the electron stays in the non-Rashba arm, while it resides in the Rashba arm for zero (or negative) magnetic field. The average kinetic energy in the two arms of the ring are found to be very different. It also reveals different "spin temperature" in the two arms of the non-reciprocal ring. The electrons are sorted according to their spins in different regions of the ring by switching on and off (or reverse) the magnetic field, thereby creating order without doing work on the system. This resembles the action of a demon in the spirit of Maxwell's original proposal, exploiting a non-classical internal degree of freedom. Our demon clearly demonstrates some of the required features on the nanoscale.