Unscrambling entanglement through a complex medium

Valencia, N. H., Goel, S., McCutcheon, W., Defienne, H. and Malik, M. (2020) Unscrambling entanglement through a complex medium. Nature Physics, 16(11), pp. 1112-1116. (doi: 10.1038/s41567-020-0970-1)

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The transfer of quantum information through a noisy environment is a central challenge in the fields of quantum communication, imaging and nanophotonics. In particular, high-dimensional quantum states of light enable quantum networks with significantly higher information capacities and noise robustness as compared with qubits. However, although qubit entanglement has been distributed over large distances through free space and fibre, the transport of high-dimensional entanglement is hindered by the complexity of the channel, which encompasses effects such as free-space turbulence or mode mixing in multimode waveguides. Here, we demonstrate the transport of six-dimensional spatial-mode entanglement through a 2-m-long, commercial multimode fibre with 84.4% fidelity. We show how the entanglement can itself be used to measure the transmission matrix of the complex medium, allowing the recovery of quantum correlations that were initially lost. Using a unique property of entangled states, the medium is rendered transparent to entanglement by carefully ‘scrambling’ the photon that did not enter it, rather than unscrambling the photon that did. Our work overcomes a primary challenge in the fields of quantum communication and imaging, and opens a new pathway towards the control of complex scattering processes in the quantum regime.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Defienne, Dr Hugo
Authors: Valencia, N. H., Goel, S., McCutcheon, W., Defienne, H., and Malik, M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Nature Physics
Publisher:Nature Publishing Group
ISSN (Online):1745-2481
Copyright Holders:Copyright © 2020, The Author(s), under exclusive licence to Springer Nature Limited
First Published:First published in Nature Physics 16(11):1112-1116
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
305457Adaptive Optics for Quantum CommunicationDaniele FaccioEuropean Commission (EC)840958P&S - Physics & Astronomy