000133447 001__ 133447 000133447 005__ 20250923084427.0 000133447 0247_ $$2doi$$a10.1103/PhysRevA.109.033715 000133447 0248_ $$2sideral$$a138130 000133447 037__ $$aART-2024-138130 000133447 041__ $$aeng 000133447 100__ $$0(orcid)0000-0002-6123-8165$$aTerradas-Briansó, Sergi 000133447 245__ $$aWaveguide QED in the dipole gauge 000133447 260__ $$c2024 000133447 5060_ $$aAccess copy available to the general public$$fUnrestricted 000133447 5203_ $$aIn recent studies on ultrastrong coupling between matter and light in cavities, the significance of gauge choice when employing the widely used two-level approximation has been highlighted. Expanding upon these investigations, we extend the analysis to waveguide QED, where we demonstrate that truncations performed in the dipole gauge also yield accurate results. To illustrate this point, we consider the case of a dipole coupled to a cavity array. Various numerical and analytical techniques have been employed to investigate the low-energy dynamics of the system. Leveraging these theoretical tools, we argue that single-photon scattering is an ideal method for investigating gauge-related issues. Our findings reveal two effects in the scattering spectra, which cannot be reproduced in a truncated model using the Coulomb gauge. First, the primary resonance is modified due to a Lamb shift contribution. Second, we observe asymmetric transmission amplitudes surrounding this resonance, reflecting the asymmetry of the spectral density in this model. Additionally, we explore other features in the scattering spectra resulting from ultrastrong couplings, such as the emergence of Fano resonances and inelastic channels. Finally, we propose an experimental test of our ideas in the context of circuit QED. 000133447 536__ $$9info:eu-repo/grantAgreement/ES/DGA/E09-17R-Q-MAD$$9info:eu-repo/grantAgreement/ES/MCIU/PID2020-Q1115221GB-C41$$9info:eu-repo/grantAgreement/EUR/MICINN/TED2021-131447B-C21 000133447 540__ $$9info:eu-repo/semantics/openAccess$$aAll rights reserved$$uhttp://www.europeana.eu/rights/rr-f/ 000133447 590__ $$a2.9$$b2024 000133447 592__ $$a1.033$$b2024 000133447 591__ $$aPHYSICS, ATOMIC, MOLECULAR & CHEMICAL$$b13 / 39 = 0.333$$c2024$$dQ2$$eT2 000133447 593__ $$aAtomic and Molecular Physics, and Optics$$c2024$$dQ1 000133447 591__ $$aOPTICS$$b53 / 125 = 0.424$$c2024$$dQ2$$eT2 000133447 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000133447 700__ $$0(orcid)0000-0001-9273-8165$$aMartín-Moreno, Luis 000133447 700__ $$0(orcid)0000-0003-4478-1948$$aZueco, David 000133447 773__ $$g109, 3 (2024), e033715 [13 pp.]$$pPhys. rev., A$$tPhysical Review A$$x2469-9926 000133447 8564_ $$s1666509$$uhttps://zaguan.unizar.es/record/133447/files/texto_completo.pdf$$yVersión publicada 000133447 8564_ $$s3215561$$uhttps://zaguan.unizar.es/record/133447/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000133447 909CO $$ooai:zaguan.unizar.es:133447$$particulos$$pdriver 000133447 951__ $$a2025-09-22-14:40:25 000133447 980__ $$aARTICLE