The thermodynamic phases of many-body systems within cavities have been of perennial interest since the seminal work of Dicke, Hepp and Lieb. Determining what phase transitions may occur and how to classify them, has become a rich inter-disciplinary field, with connections to quantum chaos, to driven and open quantum systems theory, and to the theory of superconducting circuits. It has also given rise to extensive foundational debates surrounding the role and importance of gauge-freedom and the validity of traditional models in cavity QED.

Recently, these topics have received renewed interest, stimulated by various contemporary theoretical studies on ultra-strongly coupled magnonic cavity QED systems and strongly correlated electrons coupled to one- and two-dimensional fields [1-7]. Many open challenges remain in revealing the rich phase diagrams of such systems, including the roles played by strong light-matter interactions, gauge-freedom, and the legitimacy of approximations.

The purpose of this mini-colloquium is to bring together diverse researchers of light-matter physics, condensed matter, and statistical physics to present and discuss emerging theoretical, numerical, and experimental results, to share ideas, and to understand and expand the scope of future research on the thermodynamics of many-body cavity QED systems.

References

[1] Phys. Rev. A 97, 043820, (2018)

[2] Phys. Rev. B 100 (12), 121109 (2019)

[3] Phys. Rev. B 102(12), 125137 (2020)

[4] Commun. Physics 5, 3 (2022)  

[5] Phys. Rev. Lett. 125, 257604 (2020)

[6] Phys. Rev. Lett. 122, 017401, (2019)

[7] Phys. Rev. Lett. 123, 207402, (2019)