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.

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.