Quantum state engineering using one-dimensional discrete-time quantum walks

Innocenti, Luca; Majury, Helena; Giordani, Taira; Spagnolo, Nicolò; Sciarrino, Fabio; Paternostro, Mauro; Ferraro, Alessandro

doi:10.1103/physreva.96.062326

Cited by 46 publications

(43 citation statements)

References 75 publications

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“…For example, it was pointed out that using the localization like effects in QWs, one can engineer a state of walker and obtain specific desired details for its state [59,60]. In [61], a beautiful theoretical framework was proposed for quantum state engineering of arbitrary superpositions of the walkers sites. Experimentally, Nitsche et al used QWs with dynamical control to prepare non-localized input states and implement a state transfer scheme for an arbitrary input state [62].…”

Section: Discussion On Physical Interpretationsmentioning

confidence: 99%

Controlling quantum random walk with a step-dependent coin

Panahiyan

Fritzsche

2018

New J. Phys.

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We report on the possibility of controlling quantum random walks (QWs) with a step-dependent coin (SDC). The coin is characterized by a (single) rotation angle. Considering different rotation angles, one can find diverse probability distributions for this walk including: complete localization, Gaussian and asymmetric likes. In addition, we explore the entropy of walk in two contexts; for probability density distributions over position space and walkerʼs internal degrees of freedom space (coin space). We show that entropy of position space can decrease for a SDC with the step-number, quite in contrast to a walk with step-independent coin (SIC). For entropy of coin space, a damped oscillation is found for walk with SIC while for a SDC case, the behavior of entropy depends on rotation angle. In general, we demonstrate that quantum walks with simple initiatives may exhibit a quite complex and varying behavior if SDCs are applied. This provides the possibility of controlling QW with a SDC.

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Section: Discussion On Physical Interpretationsmentioning

confidence: 99%

Controlling quantum random walk with a step-dependent coin

Panahiyan

Fritzsche

2018

New J. Phys.

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“…The study of structured light is an important field of investigation in both the quantum and classical regimes. 1,2 In particular, light carrying orbital angular momentum (OAM) different from zero has been used in many applications ranging from quantum simulation 3,4 and quantum engineering 5,6 to quantum and classical communications. [7][8][9][10][11][12][13][14] Recently, OAM modes have been particularly studied for their uses in biomedical applications of imaging and diagnosis.…”

Section: Introductionmentioning

confidence: 99%

Transmission of vector vortex beams in dispersive media

et al. 2020

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Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues. Finding appropriate strategies to increase the robustness to scattering is the common requirement in developing both communication protocols and imaging systems. Recently, structured light has attracted attention due to its seeming scattering resistance in terms of transmissivity and spatial behavior. Moreover, correlation between optical polarization and orbital angular momentum (OAM), which characterizes the so-called vector vortex beams (VVBs) states, seems to allow for the preservation of the polarization pattern. We extend the analysis by investigating both the spatial features and the polarization structure of vectorial optical vortexes propagating in scattering media with different concentrations. Among the observed features, we find a sudden swift decrease in contrast ratio for Gaussian, OAM, and VVB modes for concentrations of the adopted scattering media exceeding 0.09%. Our analysis provides a more general and complete study on the propagation of structured light in dispersive and scattering media.

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“…[37] provides an exact, analytical methodology for the preparation of arbitrary states of a quantum walker through only passive linear-optics transformation. This would thus provide the way to engineer initial states of the walker such as the one in Eq.…”

Section: Experimental Proposalmentioning

confidence: 99%

Robust quantum state engineering through coherent localization in biased-coin quantum walks

Majury

Boutari

O’Sullivan

et al. 2018

EPJ Quantum Technol.

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We address the performance of a coin-biased quantum walk as a generator for non-classical position states of the walker. We exploit a phenomenon of coherent localization in the position space -resulting from the choice of small values of the coin parameter and assisted by post-selection -to engineer large-size coherent superpositions of position states of the walker. The protocol that we design appears to be remarkably robust against both the actual value taken by the coin parameter and strong dephasing-like noise acting on the spatial degree of freedom. We finally illustrate a possible linear-optics implementation of our proposal, suitable for both bulk and integrated-optics platforms.Quantum walks, which generalize the well-known concept of random walks to the quantum domain, have recently attracted considerable attention in light of the possibility that they offer the capability to explore non-trivial phenomena in statistical mechanics [1], such as interference [2], localization [3-6] and tunnelling, and are able to establish entanglement among either the different degrees of freedom of a walker, or the parties of a multi-walker setting [7][8][9][10][11][12][13]. Quantum walk-based architectures for quantum computation have been proposed and theoretically explored [14], while the possibility to implement quantum simulation through schemes based on the dynamics of a quantum walker are currently being pursued both theoretically and experimentally.In the last few years, the number of experimental validations of the quantum walk paradigm, and investigations towards its use for the coherent manipulation of information at the quantum mechanical level have flourished [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. This therefore paves the way to the full exploitation of the possibilities offered by quantum walks for quantum state engineering in Hilbert spaces of large dimensions, which is in general a difficult task to pursue experimentally.In this paper, we explore exactly such a possibility and exploit the statistical features of a discrete-time quantum walk to engineer non-classical states of an N -dimensional system. Specifically, we make use of special coherent localization effects induced on the position state of a quantum walker by choosing properly the operation describing the tossing of a coin. We demonstrate that high-quality coherent superpositions of fully position states © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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Quantum state engineering using one-dimensional discrete-time quantum walks

Cited by 46 publications

References 75 publications

Controlling quantum random walk with a step-dependent coin

Controlling quantum random walk with a step-dependent coin

Transmission of vector vortex beams in dispersive media

Robust quantum state engineering through coherent localization in biased-coin quantum walks

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