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We theoretically study the propagation of light through a cold atomic medium, where the effects of motion, laser intensity, atomic density, and polarization can all modify the properties of the scattered light. We present two different…

Quantum Physics · Physics 2016-08-24 Bihui Zhu , John Cooper , Jun Ye , Ana Maria Rey

We propose a novel implementation of discrete time quantum walks for a neutral atom in an array of optical microtraps or an optical lattice. We analyze a one-dimensional walk in position space, with the coin, the additional qubit degree of…

Quantum Physics · Physics 2009-11-11 K. Eckert , J. Mompart , G. Birkl , M. Lewenstein

We investigate a system of two atoms in an optical lattice, performing a quantum walk by state-dependent shift operations and a coin operation acting on the internal states. The atoms interact, e.g., by cold collisions, whenever they are in…

We study the asymptotic position distribution of general quantum walks on a lattice, including walks with a random coin, which is chosen from step to step by a general Markov chain. In the unitary (i.e., non-random) case, we allow any…

Quantum Physics · Physics 2011-04-21 Andre Ahlbrecht , Holger Vogts , Albert H. Werner , Reinhard F. Werner

We study a spin-1/2-particle moving on a one dimensional lattice subject to disorder induced by a random, space-dependent quantum coin. The discrete time evolution is given by a family of random unitary quantum walk operators, where the…

Quantum Physics · Physics 2015-05-27 Andre Ahlbrecht , Volkher B. Scholz , Albert H. Werner

Inspired by the classical phenomenon of random walk, the concept of quantum walk has emerged recently as a powerful platform for the dynamical simulation of complex quantum systems, entanglement production and universal quantum computation.…

A particular family of time- and space-dependent discrete-time quantum walks (QWs) is considered in one dimensional physical space. The continuous limit of these walks is defined through a new procedure and computed in full detail. In this…

Quantum Physics · Physics 2017-04-25 Di Molfetta Giuseppe , Fabrice Debbasch , Marc E Brachet

We consider a new model of quantum walk on a one-dimensional momentum space that includes both discrete jumps and continuous drift. Its time evolution has two stages; a Markov diffusion followed by localized dynamics. As in the well known…

Quantum Physics · Physics 2009-11-10 A. Romanelli , A. Auyuanet , R. Siri , G. Abal , R. Donangelo

Quantum walks have a host of applications, ranging from quantum computing to the simulation of biological systems. We present an intrinsically stable, deterministic implementation of discrete quantum walks with single photons in space. The…

Quantum Physics · Physics 2010-04-21 M. A. Broome , A. Fedrizzi , B. P. Lanyon , I. Kassal , A. Aspuru-Guzik , A. G. White

Quantum random walks are shown to have non-intuitive dynamics which makes them an attractive area of study for devising quantum algorithms for long-standing open problems as well as those arising in the field of quantum computing. In the…

Quantum Physics · Physics 2009-11-13 K. Manouchehri , J. B. Wang

We investigate continuous-time quantum walks of two fermionic atoms loaded in one-dimensional optical lattices with on-site interaction and subjected to a Zeeman field. The quantum walks are accompanied by spin-flipping processes. We…

Quantum Gases · Physics 2016-04-20 Li Wang , Na Liu , Shu Chen , Yunbo Zhang

When particles move through a crystal or optical lattice, their motion can sometimes become frozen by strong external forces -- yet collective motion may still emerge through subtle many-body effects. In this work, we explore such…

Random walks describe diffusion processes, where movement at every time step is restricted to only the neighbouring locations. We construct a quantum random walk algorithm, based on discretisation of the Dirac evolution operator inspired by…

Quantum Physics · Physics 2015-03-13 Apoorva Patel , Md. Aminoor Rahaman

The development of quantum walks in the context of quantum computation, as generalisations of random walk techniques, led rapidly to several new quantum algorithms. These all follow unitary quantum evolution, apart from the final…

Quantum Physics · Physics 2008-03-02 Viv Kendon

We investigate the linear dynamics of an electromagnetic field propagating in curved spacetime in the presence of plasma. The dynamical equations are generically more involved and richer than the effective Proca equation adopted as a model…

General Relativity and Quantum Cosmology · Physics 2021-06-30 Enrico Cannizzaro , Andrea Caputo , Laura Sberna , Paolo Pani

We investigate the spectral properties of a hole moving in a two-dimensional Hubbard model for strongly correlated t_2g electrons. Although superexchange interactions are Ising-like, a quasi-one-dimensional coherent hole motion arises due…

Strongly Correlated Electrons · Physics 2008-02-15 M. Daghofer , K. Wohlfeld , A. M. Oles , E. Arrigoni , P. Horsch

Quantum walks, in virtue of the coherent superposition and quantum interference, possess exponential superiority over its classical counterpart in applications of quantum searching and quantum simulation. The quantum enhanced power is…

The electron spin transport in condensed matter, Spintronics, is a subject of rapidly growing interest both scientifically and from the point of view of applications to modern and future electronics. In many cases the electron spin…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Israel D. Vagner

We investigate the ballistic spreading behavior of the one-dimensional discrete time quantum walks whose time evolution is driven by any balanced quantum coin. We obtain closed-form expressions for the long-time variance of position of…

Quantum Physics · Physics 2017-12-07 Alexandre C. Orthey , Edgard P. M. Amorim

We investigate quantum walks in multiple dimensions with different quantum coins. We augment the model by assuming that at each step the amplitudes of the coin state are multiplied by random phases. This model enables us to study in detail…

Quantum Physics · Physics 2009-11-13 Jozef Kosik , Vladimir Buzek , Mark Hillery