Adjustable-depth quantum circuit for position-dependent coin operators of discrete-time quantum walks

Fuente: arXiv
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Autori principali: Nzongani, Ugo, Arnault, Pablo
Natura: Preprint
Pubblicazione: 2023
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author Nzongani, Ugo
Arnault, Pablo
author_facet Nzongani, Ugo
Arnault, Pablo
contents Discrete-time quantum walks with position-dependent coin operators have numerous applications. For a position dependence that is sufficiently smooth, it has been provided in Ref. [1] an approximate quantum-circuit implementation of the coin operator that is efficient. If we want the quantum-circuit implementation to be exact (e.g., either, in the case of a smooth position dependence, to have a perfect precision, or in order to treat a non-smooth position dependence), but the depth of the circuit not to scale exponentially, then we can use the linear-depth circuit of Ref. [1], which achieves a depth that is linear at the cost of introducing an exponential number of ancillas. In this paper, we provide an adjustable-depth quantum circuit for the exact implementation of the position-dependent coin operator. This adjustable-depth circuit consists in (i) applying in parallel, with a linear-depth circuit, only certain packs of coin operators (rather than all of them as in the original linear-depth circuit [1]), each pack contributing linearly to the depth, and in (ii) applying sequentially these packs, which contributes exponentially to the depth.
format Preprint
id arxiv_https___arxiv_org_abs_2304_10460
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Adjustable-depth quantum circuit for position-dependent coin operators of discrete-time quantum walks
Nzongani, Ugo
Arnault, Pablo
Quantum Physics
Emerging Technologies
Discrete-time quantum walks with position-dependent coin operators have numerous applications. For a position dependence that is sufficiently smooth, it has been provided in Ref. [1] an approximate quantum-circuit implementation of the coin operator that is efficient. If we want the quantum-circuit implementation to be exact (e.g., either, in the case of a smooth position dependence, to have a perfect precision, or in order to treat a non-smooth position dependence), but the depth of the circuit not to scale exponentially, then we can use the linear-depth circuit of Ref. [1], which achieves a depth that is linear at the cost of introducing an exponential number of ancillas. In this paper, we provide an adjustable-depth quantum circuit for the exact implementation of the position-dependent coin operator. This adjustable-depth circuit consists in (i) applying in parallel, with a linear-depth circuit, only certain packs of coin operators (rather than all of them as in the original linear-depth circuit [1]), each pack contributing linearly to the depth, and in (ii) applying sequentially these packs, which contributes exponentially to the depth.
title Adjustable-depth quantum circuit for position-dependent coin operators of discrete-time quantum walks
topic Quantum Physics
Emerging Technologies
url https://arxiv.org/abs/2304.10460