Multidimensional entanglement transport through single-mode fiber

Jun Liu; Isaac Nape; Qainke Wang; Adam Vallés; Jian Wang; Andrew Forbes

doi:10.1126/sciadv.aay0837

Multidimensional entanglement transport through single-mode fiber

Sci Adv. 2020 Jan 24;6(4):eaay0837. doi: 10.1126/sciadv.aay0837. eCollection 2020 Jan.

Authors

Jun Liu¹, Isaac Nape², Qainke Wang¹, Adam Vallés², Jian Wang¹, Andrew Forbes^{1

2}

Affiliations

¹ Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China.
² School of Physics, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa.

Abstract

The global quantum network requires the distribution of entangled states over long distances, with substantial advances already demonstrated using polarization. While Hilbert spaces with higher dimensionality, e.g., spatial modes of light, allow higher information capacity per photon, such spatial mode entanglement transport requires custom multimode fiber and is limited by decoherence-induced mode coupling. Here, we circumvent this by transporting multidimensional entangled states down conventional single-mode fiber (SMF). By entangling the spin-orbit degrees of freedom of a biphoton pair, passing the polarization (spin) photon down the SMF while accessing multiple orbital angular momentum (orbital) subspaces with the other, we realize multidimensional entanglement transport. We show high-fidelity hybrid entanglement preservation down 250 m SMF across multiple 2 × 2 dimensions, confirmed by quantum state tomography, Bell violation measures, and a quantum eraser scheme. This work offers an alternative approach to spatial mode entanglement transport that facilitates deployment in legacy networks across conventional fiber.

Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).