Reversible Mapping and Sorting the Spin of Photons on the Nanoscale: A Spin-Optical Nanodevice

• Published in: Nano letters Vol. 19; no. 5; pp. 3364 - 3369
• Main Authors: Krauss, Enno, Razinskas, Gary, Köck, Dominik, Grossmann, Swen, Hecht, Bert
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.05.2019
• Subjects: Surface plasmon polaritons; Poincaré-sphere; optical nanocircuitry; spin−orbit interaction; plasmonic waveguides; photonic spin-Hall effect; Poincaré-sphere
• ISSN: 1530-6984; 1530-6992; 1530-6992
• DOI: 10.1021/acs.nanolett.9b01162

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 pseudospin embodied by the two fundamental modes of a subwavelength plasmonic two-wire transmission line. We design a device in which this pseudospin evolves in a well-defined fashion throughout the device reminiscent of the evolution of photon polarization in a birefringent medium and the behavior of electron spins in the channel of a spin field-effect transistor. The significance of this pseudospin is enriched by the fact that it is subject to spin–orbit locking. Combined with optically active materials to exert external control over the pseudospin precession, our findings could enable spin-optical transistors, that is, the routing and processing of quantum information with light on a subwavelength scale.