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P · Â vs x · Ê: Gauge invariance in quantum optics and quantum field theory

Funai, Nicholas; Louko, Jorma; Martin-Martinez, Eduardo

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Authors

Nicholas Funai

JORMA LOUKO JORMA.LOUKO@NOTTINGHAM.AC.UK
Professor of Mathematical Physics

Eduardo Martin-Martinez



Abstract

We compare the predictions of the fundamentally motivated minimal coupling (^p⋅^A) and the ubiquitous dipole coupling (^x⋅^E) in the light-matter interaction. By studying the light-matter interaction for hydrogenlike atoms we find that the dipole approximation cannot be a priori justified to analyze the physics of vacuum excitations (a very important phenomenon in relativistic quantum information) since a dominant wavelength is absent in those problems, no matter how small (as compared to any frequency scale) the atom is. Remarkably, we show that the dipole approximation in those regimes can still be valid as long as the interaction time is longer than the light-crossing time of the atoms, which is a very reasonable assumption. We also highlight some of the subtleties that one has to be careful with when working with the explicitly gauge noninvariant nature of the minimal coupling, and we compare it with the explicitly gauge invariant dipole coupling.

Citation

Funai, N., Louko, J., & Martin-Martinez, E. (2019). P · Â vs x · Ê: Gauge invariance in quantum optics and quantum field theory. Physical Review D, 99(6), Article 065014. https://doi.org/10.1103/physrevd.99.065014

Journal Article Type Article
Acceptance Date Feb 28, 2019
Online Publication Date Mar 26, 2019
Publication Date Mar 15, 2019
Deposit Date Aug 22, 2019
Publicly Available Date Aug 28, 2019
Journal Physical Review D
Print ISSN 2470-0010
Electronic ISSN 2470-0029
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 99
Issue 6
Article Number 065014
DOI https://doi.org/10.1103/physrevd.99.065014
Keywords Quantum Physics; High Energy Physics - Theory
Public URL https://nottingham-repository.worktribe.com/output/2460630
Publisher URL https://journals.aps.org/prd/abstract/10.1103/PhysRevD.99.065014
Contract Date Aug 28, 2019

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