TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.15.3.113
TI  - First-order photon condensation in magnetic cavities: A two-leg ladder model
PY  - 2023/09/25
UR  - https://www.scipost.org/SciPostPhys.15.3.113
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 15
IS  - 3
SP  - 113
A1  - Bacciconi, Zeno
AU  - Andolina, Gian Marcello
AU  - Chanda, Titas
AU  - Chiriacò, Giuliano
AU  - Schirò, Marco
AU  - Dalmonte, Marcello
AB  - We consider a model of free fermions in a ladder geometry coupled to a non-uniform cavity mode via Peierls substitution. Since the cavity mode generates a magnetic field, no-go theorems on spontaneous photon condensation do not apply, and we indeed observe a phase transition to a photon condensed phase characterized by finite circulating currents, alternatively referred to as the equilibrium superradiant phase. We consider both square and triangular ladder geometries, and characterize the transition by studying the energy structure of the system, light-matter entanglement, the properties of the photon mode, and chiral currents. The transition is of first order and corresponds to a sudden change in the fermionic band structure as well as the number of its Fermi points. Thanks to the quasi-one dimensional geometry we scrutinize the accuracy of (mean field) cavity-matter decoupling against large scale density-matrix renormalization group simulations. We find that light-matter entanglement is essential for capturing corrections to matter properties at finite sizes and for the description of the correct photon state. The latter remains Gaussian in the the thermodynamic limit both in the normal and photon condensed phases.
ER  -

@Article{10.21468/SciPostPhys.15.3.113,
	title={{First-order photon condensation in magnetic cavities: A two-leg ladder model}},
	author={Zeno Bacciconi and Gian M. Andolina and Titas Chanda and Giuliano Chiriacò and Marco Schirò and Marcello Dalmonte},
	journal={SciPost Phys.},
	volume={15},
	pages={113},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.15.3.113},
	url={https://scipost.org/10.21468/SciPostPhys.15.3.113},
}