Year: 2026
Type: preprint
Abstract: The Hubbard model on the honeycomb lattice is a pristine realisation of a semimetal-to-insulator Mott transition belonging to the O(3) Gross-Neveu universality class. We couple this system to a single linearly polarised, uniform cavity photon mode. For this interacting light-matter model, we formulate a negative-sign-free fermion quantum Monte Carlo algorithm that allows for unbiased results on finite system sizes. Our numerical results show that the coupling to the cavity is irrelevant at criticality, even at strong electron-photon coupling. On the other hand, we observe, and show analytically, that the photon spectrum acquires finite corrections in the form of the optical conductivity. In the semimetal phase, gapless particle-hole excitations produce a low-energy polaritonic mode, which is suppressed in the Mott insulator phase. Furthermore, we show that the photon spectra can be used to detect universal information about the quantum critical point. Thereby, our results establish that a single, uniform cavity photon mode acts as a contact-free non-invasive probe for Mott criticality. Our results can be generalised to any cavity where an intensive number of uniform linearly polarised photon modes couple to the electronic system.
Source: arXiv (Cornell University)
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: Alexander von Humboldt-Stiftung, Friedrich-Alexander-Universität Erlangen-Nürnberg, Deutsche Forschungsgemeinschaft, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Austrian Science Fund, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Instituto Serrapilheira, Gauss Centre for Supercomputing, Leibniz-Gemeinschaft
Awards: G1840770272, G2152757567, G2311368543, G2584274330, G3389371798, Numerische Simulationen von topologischen und exotischen Zuständen der QuantenMaterie, HochleistungscomputeCluster, G5428645319, G6010662946, EXC 2147: Komplexität und Topologie in Quantenmaterialien (CT.QMAT), G6690480278, Phasenübergänge jenseits des LandauGinzburgWilsonParadigmas., G7577322452, G8197580332, G8242838943
OpenAlex ID: W7163344245