A Novel Bulk-Optics Scheme for Quantum Walk with High Phase Stability

Abstract

A novel bulk optics scheme for quantum walks is presented. It consists of a one-dimensional lattice built on two concatenated displaced Sagnac interferometers that make it possible to reproduce all the possible trajectories of an optical quantum walk. Because of the closed loop configuration, the interferometric structure is intrinsically stable in phase. Moreover, the lattice structure is highly configurable, as any phase component perceived by the walker is accessible, and finally, all output modes can be measured at any step of the quantum walk evolution. We report here on the experimental implementation of ordered and disordered quantum walks.

Experimental Investigation of Superdiffusion via Coherent Disordered Quantum Walks

“…4 the expected behaviours simulated by considering ideal optical elements for the two limit cases of ordered and completely disordered QW (respectively blue and red dotted lines). They differ from the experimental data because of the non perfectly symmetric behaviour of BS 1 (see SM for details) [25]. The actual superdiffusive behaviour of the experimental evolutions is shown in Tab.…”

“…The output modes of each step can be extracted for measurement by a set of Moving Mirros (MMs), intersecting and extracting from the setup only the modes at the selected step N j , without intersecting the steps N < N j . The extracted radiation is then coupled on a single mode fiber and measured (for further details on the setup see [24] and [25]). A slight modification of the setup allows to inject two distinguishable or indistinguishable photons through the two different input ports of BS 1 .…”

Quantum-clustered two-photon walks

“…Losses, decoherence, and chip imperfections will of course limit the possible walk lengths of experimental implementations. Up to this point, quantum walks of both single photons and of entangled photon pairs have typically been implemented using integrated optics for walks of lengths on the order of five to ten time steps (for example, [15,[28][29][30]), although proposals have been made for arrangements that may allow longer walks [31]. In what follows, we assume an idealized system, neglecting losses and other imperfections.…”

Enhancing nonclassical bosonic correlations in a Quantum Walk network through experimental control of disorder

“…The extracted radiation is then coupled to a single-mode fiber and measured (for further details on the setup see Ref. [46,56]). Using couplers to collect the extracted photons, we can measure coincidences between all possible modes at each step and experimentally reconstruct the two-photon probability distribution.…”