# A Spin-Optical Nano Device

## TL;DR

This paper demonstrates a device that maps photon polarization to a pseudo-spin in a plasmonic waveguide, enabling spin-controlled optical information processing at the nanoscale.

## Contribution

It introduces a novel nano device that converts photon polarization into a pseudo-spin within a plasmonic structure, facilitating spin-based optical control.

## Key findings

- Photon polarization can be mapped to a pseudo-spin in a plasmonic waveguide.
- The pseudo-spin exhibits spin-orbit locking and controlled precession.
- Potential for spin-optical transistors for quantum information processing.

## Abstract

The photon spin is an important resource for quantum information processing as is the electron spin in spintronics. However, for subwavelength confined optical excitations, polarization as a global property of a mode cannot be defined. Here, we show that any polarization state of a plane-wave photon can reversibly be mapped to a pseudo-spin embodied by the two fundamental modes of a subwavelength plasmonic two-wire transmission line. We design a device in which this pseudo-spin evolves in a well-defined fashion throughout the device reminiscent of the evolution of photon polarization in a birefringent medium and the behaviour of electron spins in the channel of a spin field-effect transistor. The significance of this pseudo-spin is enriched by the fact that it is subject to spin-orbit locking. Combined with optically active materials to exert external control over the pseudo-spin precession, our findings could enable spin-optical transistors, i.e. the routing and processing of quantum information with light on a subwavelength scale.

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Source: https://tomesphere.com/paper/1812.03721