Quantum walks in external gauge fields

verfasst von: C. Cedzich, T. Geib, A. H. Werner, R. F. Werner
Abstract: Describing a particle in an external electromagnetic field is a basic task of quantum mechanics. The standard scheme for this is known as "minimal coupling" and consists of replacing the momentum operators in the Hamiltonian by the modified ones with an added vector potential. In lattice systems, it is not so clear how to do this because there is no continuous translation symmetry, and hence, there are no momenta. Moreover, when time is also discrete, as in quantum walk systems, there is no Hamiltonian, but only a unitary step operator. We present a unified framework of gauge theory for such discrete systems, keeping a close analogy to the continuum case. In particular, we show how to implement minimal coupling in a way that automatically guarantees unitary dynamics. The scheme works in any lattice dimension, for any number of internal degrees of freedom, for walks that allow jumps to a finite neighbourhood rather than to nearest neighbours, is naturally gauge invariant, and prepares possible extensions to non-abelian gauge groups.
Organisationseinheit(en): Fakultät für Mathematik und Physik
Institut für Theoretische Physik
SFB 1227: Designte Quantenzustände der Materie (DQ-mat)
Externe Organisation(en): Universität zu Köln
University of Copenhagen
Typ: Artikel
Journal: Journal of Mathematical Physics
Band: 60
ISSN: 0022-2488
Publikationsdatum: 01.2019
Publikationsstatus: Veröffentlicht
Peer-reviewed: Ja
ASJC Scopus Sachgebiete: Statistische und nichtlineare Physik, Mathematische Physik
Elektronische Version(en): https://doi.org/10.48550/arXiv.1808.10850 (Zugang: Offen)
https://doi.org/10.1063/1.5054894 (Zugang: Geschlossen)

BibTeX

@article{4a4598a899d248609cbffa7f0e54e7a7,
title = "Quantum walks in external gauge fields",
abstract = "Describing a particle in an external electromagnetic field is a basic task of quantum mechanics. The standard scheme for this is known as {"}minimal coupling{"} and consists of replacing the momentum operators in the Hamiltonian by the modified ones with an added vector potential. In lattice systems, it is not so clear how to do this because there is no continuous translation symmetry, and hence, there are no momenta. Moreover, when time is also discrete, as in quantum walk systems, there is no Hamiltonian, but only a unitary step operator. We present a unified framework of gauge theory for such discrete systems, keeping a close analogy to the continuum case. In particular, we show how to implement minimal coupling in a way that automatically guarantees unitary dynamics. The scheme works in any lattice dimension, for any number of internal degrees of freedom, for walks that allow jumps to a finite neighbourhood rather than to nearest neighbours, is naturally gauge invariant, and prepares possible extensions to non-abelian gauge groups.",
author = "C. Cedzich and T. Geib and Werner, {A. H.} and Werner, {R. F.}",
note = "Funding information: A. H. Werner thanks the Humboldt Foundation for its support with a Feodor Lynen Fellowship and the VILLUM FONDEN via the QMATH Centre of Excellence (Grant No. 10059). C. Cedzich acknowledges support by the Excellence Initiative of the German Federal and State Governments (ZUK 81) and the DFG (Project No. B01 of CRC 183). T. Geib and R. F. Werner acknowledge support from the ERC grant DQSIM, the DFG SFB 1227 DQmat, and the European project SIQS.",
year = "2019",
month = jan,
doi = "10.48550/arXiv.1808.10850",
language = "English",
volume = "60",
journal = "Journal of Mathematical Physics",
issn = "0022-2488",
publisher = "American Institute of Physics",
number = "1",
}