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TT: Fachverband Tiefe Temperaturen

TT 24: Quantum-Critical Phenomena

TT 24.5: Talk

Tuesday, March 19, 2024, 10:30–10:45, H 2053

(Almost) Everything is a Dicke model — •Andreas Schellenberger and Kai Phillip Schmidt — FAU Erlangen-Nürnberg, Erlangen, Deutschland

We investigate classes of interacting quantum spin systems in a single-mode cavity with a Dicke coupling, as a paradigmatic example of correlated light-matter systems. Coming from the limit of weak light-matter couplings and large system sizes, we map the relevant low-energy sector of these models onto the exactly solvable Dicke model.

We apply the outcomes to the Dicke-Ising model as a paradigmatic example [1,2], in agreement with results obtained by mean-field theory [2]. We further accompany and verify our findings with finite-size calculations, using exact diagonalization and the series expansion method pcst++ [3].

[1] J. Rohn et al., Phys. Rev. Research 2 (2020) 023131

[2] Y. Zhang et al., Sci Rep 4 (2014) 4083

[3] L. Lenke et al., Phys. Rev. A 108 (2023)

Keywords: Light-matter system; Dicke-Ising model; Thermodynamic limit; Series expansion method