title: Two-photon quantum walk in a multimode fiber.
abstract: Multiphoton propagation in connected structures-a quantum walk-offers the potential of simulating complex physical systems and provides a route to universal quantum computation. Increasing the complexity of quantum photonic networks where the walk occurs is essential for many applications. We implement a quantum walk of indistinguishable photon pairs in a multimode fiber supporting 380 modes. Using wavefront shaping, we control the propagation of the two-photon state through the fiber in which all modes are coupled. Excitation of arbitrary output modes of the system is realized by controlling classical and quantum interferences. This report demonstrates a highly multimode platform for multiphoton interference experiments and provides a powerful method to program a general high-dimensional multiport optical circuit. This work paves the way for the next generation of photonic devices for quantum simulation, computing, and communication.
authors.affiliation: Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, F-75005 Paris, France.
authors.forename: Hugo
authors.initials: H
authors.lastname: Defienne
authors.affiliation: Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Rome, Italy.
authors.forename: Marco
authors.identifier: 0000-0003-2057-9104
authors.initials: M
authors.lastname: Barbieri
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, OX1 3PU Oxford, UK.
authors.forename: Ian A
authors.identifier: 0000-0002-4714-0575
authors.initials: IA
authors.lastname: Walmsley
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, OX1 3PU Oxford, UK.
authors.forename: Brian J
authors.identifier: 0000-0003-0835-9555
authors.initials: BJ
authors.lastname: Smith
authors.affiliation: Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, F-75005 Paris, France.
authors.forename: Sylvain
authors.identifier: 0000-0002-9914-6231
authors.initials: S
authors.lastname: Gigan
mesh_terms: D008962:Models, Theoretical; D055100:Optical Fibers; D017785:Photons; D011789:Quantum Theory
keywords: Random medium; Transmission matrix; multimode fiber; photon pairs; quantum interferences; quantum walks; scattering medium; spatial light modulator; wavefront shaping