Abstract

As a discrete-time quantum walk model on the one-dimensional integer lattice , the quantum walk recently constructed by Wang and Ye [Caishi Wang and Xiaojuan Ye, Quantum walk in terms of quantum Bernoulli noises, Quantum Information Processing 15 (2016), 1897–1908] exhibits quite different features. In this paper, we extend this walk to a higher dimensional case. More precisely, for a general positive integer , by using quantum Bernoulli noises we introduce a model of discrete-time quantum walk on the d-dimensional integer lattice , which we call the d-dimensional QBN walk. The d-dimensional QBN walk shares the same coin space with the quantum walk constructed by Wang and Ye, although it is a higher dimensional extension of the latter. Moreover we prove that, for a range of choices of its initial state, the d-dimensional QBN walk has a limit probability distribution of d-dimensional standard Gauss type, which is in sharp contrast with the case of the usual higher dimensional quantum walks. Some other results are also obtained.

Highlights

  • As quantum analogs of classical random walks, quantum walks [1] have found wide application in quantum information, quantum computing and many other fields [2,3]

  • Quantum Bernoulli noises refer to the family of annihilation and creation operators acting on Bernoulli functionals, which satisfy a canonical anti-commutation relation (CAR) in equal time, and can provide an approach to the effects of environment on an open quantum system [7,8]

  • This just means that l 2 (Zd ) describes the position of the d-dimensional QBN walk, while H describes its internal degrees of freedom

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Summary

Introduction

As quantum analogs of classical random walks, quantum walks [1] have found wide application in quantum information, quantum computing and many other fields [2,3]. In 2016, by using quantum Bernoulli noises, Wang and Ye [9] introduced a discrete-time quantum walk model on the one-dimensional integer lattice Z, which we call the one-dimensional QBN walk below. Belonging to the category of unitary quantum walks, the one-dimensional QBN walk, exhibits quite different features It takes the space H of square integrable Bernoulli functionals as its coin space, has infinitely many internal degrees of freedom since H is infinite-dimensional. By taking the operators Cn , ε ∈ {−1, +1}d , n ≥ 0 as coin operators, we establish a model of discrete-time quantum walk on Zd , which we call the d-dimensional QBN walk Of this walk, we obtain a unitary representation in the function space l 2 Zd , H and a characterization in the tensor space l 2 Zd ⊗ H.

Preliminaries
Definition and Fundamental Properties
Coin Operators
Definition and Unitary Representation
Characterization in Tensor Space
Amplitude Formula
Limit Probability Distribution
Conclusions
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