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A discrete-time Quantum Walk (QW) is essentially an operator driving the evolution of a single particle on the lattice, through local unitaries. Some QWs admit a continuum limit, leading to well-known physics partial differential equations,…

Quantum Physics · Physics 2018-06-20 Pablo Arrighi , Giuseppe Di Molfetta , Iván Márquez-Martín , Armando Pérez

A continuous-time quantum walk is modelled using a graph. In this short paper, we provide lower bounds on the size of a graph that would allow for some quantum phenomena to occur. Among other things, we show that, in the adjacency matrix…

Combinatorics · Mathematics 2018-05-23 Gabriel Coutinho

We obtain some rigorous results on limit theorems for quantum walks driven by many coins introduced by Brun et al. in the long time limit. The results imply that whether the behavior of a particle is quantum or classical depends on the…

Quantum Physics · Physics 2009-02-06 Etsuo Segawa , Norio Konno

The effect of unitary noise on the discrete one-dimensional quantum walk is studied using computer simulations. For the noiseless quantum walk, starting at the origin (n=0) at time t=0, the position distribution Pt(n) at time t is very…

Quantum Physics · Physics 2009-11-10 Daniel Shapira , Ofer Biham , A. J. Bracken , Michelle Hackett

We present a discrete-time, one-dimensional quantum walk based on the entanglement between the momentum of ultracold rubidium atoms (the walk space) and two internal atomic states (the "coin" degree of freedom). Our scheme is highly…

Quantum Physics · Physics 2018-09-26 Siamak Dadras , Alexander Gresch , Caspar Groiseau , Sandro Wimberger , Gil S. Summy

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 use discrete-event simulation on a digital computer to study two different models of experimentally realizable quantum walks. The simulation models comply with Einstein locality, are as "realistic" as the one of the simple random walk in…

Quantum Physics · Physics 2020-05-08 Madita Willsch , Dennis Willsch , Kristel Michielsen , Hans De Raedt

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

In this paper we present closed-form expressions for the wave function that governs the evolution of the discrete-time quantum walk on a line when the coin operator is arbitrary. The formulas were derived assuming that the walker can either…

Quantum Physics · Physics 2015-02-18 Miquel Montero

Quantum walks are promising for information processing tasks because on regular graphs they spread quadratically faster than random walks. Static disorder, however, can turn the tables: unlike random walks, quantum walks can suffer Anderson…

Mesoscale and Nanoscale Physics · Physics 2015-11-18 Tibor Rakovszky , Janos K. Asboth

We consider a network model, embedded on the Manhattan lattice, of a quantum localisation problem belonging to symmetry class C. This arises in the context of quasiparticle dynamics in disordered spin-singlet superconductors which are…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 E. J. Beamond , A. L. Owczarek , John Cardy

The quantum walk was originally proposed as a quantum mechanical analogue of the classical random walk, and has since become a powerful tool in quantum information science. In this paper, we show that discrete time quantum walks provide a…

Mesoscale and Nanoscale Physics · Physics 2010-09-30 Takuya Kitagawa , Mark S. Rudner , Erez Berg , Eugene Demler

We study the evolution of a random walker on a conservative dynamic random environment composed of independent particles performing simple symmetric random walks, generalizing results of [16] to higher dimensions and more general transition…

A discrete-time Quantum Walk (QW) is an operator driving the evolution of a single particle on the lattice, through local unitaries. Some QW admit, as their continuum limit, a well-known equation of Physics. In arXiv:1803.01015 the QW is…

Quantum Physics · Physics 2018-12-07 Pablo Arrighi , Giuseppe Di Molfetta , Iván Márquez-Martín , Armando Pérez

We construct a new type of quantum walks on simplicial complexes as a natural extension of the well-known Szegedy walk on graphs. One can numerically observe that our proposing quantum walks possess linear spreading and localization as in…

Mathematical Physics · Physics 2015-08-05 Kaname Matsue , Osamu Ogurisu , Etsuo Segawa

It has been observed that quantum walks on regular lattices can give rise to wave equations for relativistic particles in the continuum limit. In this paper we define the 3D walk as a product of three coined one-dimensional walks. The…

Quantum Physics · Physics 2018-05-09 Leonard Mlodinow , Todd A. Brun

We consider a one-dimensional space-inhomogeneous discrete time quantum walk. This model is the Hadamard walk with one defect at the origin which is different from the model introduced by Wojcik et al. [14]. We obtain a stationary measure…

Mathematical Physics · Physics 2015-07-31 Takako Endo , Norio Konno , Etsuo Segawa , Masato Takei

It is well known that many real world networks have the power-law degree distribution (scale-free property). However there are no rigorous results for continuous-time quantum walks on such realistic graphs. In this paper, we analyze…

Quantum Physics · Physics 2010-11-12 Yusuke Ide , Norio Konno

We systematically study the localization effect in discrete-time quantum walks on a honeycomb network and establish the mathematical framework. We focus on the Grover walk first and rigorously derive the limit form of the walker's state,…

Quantum Physics · Physics 2015-11-11 Changyuan Lyu , Luyan Yu , Shengjun Wu

A discrete-time Quantum Walk (QW) is essentially a unitary operator driving the evolution of a single particle on the lattice. Some QWs admit a continuum limit, leading to familiar PDEs (e.g. the Dirac equation). In this paper, we study the…

Quantum Physics · Physics 2016-04-29 Pablo Arrighi , Stefano Facchini , Marcelo Forets