Description
Ultrastrong light–matter interaction in solids can reveal collective optical phenomena that are traditionally studied in quantum optics [1]. We explore Dicke phenomena in materials. We demonstrated superfluorescence in electron–hole ensembles [2], a burst of emission where peak intensity scales as $N^2$ [3]. We also observe cooperative radiative damping of cyclotron resonance in a 2D electron gas [4]. Motivated by the Dicke superradiant phase transition (SRPT), we explored the ultrastrong coupling regime in Landau polaritons [5,6]. Finally, we demonstrated Dicke cooperativity [7] and the magnonic SRPT [8] in the Er$^{3+}$-Fe$^{3+}$ exchange interaction in ErFeO$_3$. These studies demonstrate that cooperative light–matter interactions profoundly shape the dynamics of correlated electrons.
References
1. K. Cong et al., J. Opt. Soc. Am. B 33, C80 (2016).
2. G. T. Noe II et al., Nat. Phys. 8, 219 (2012).
3. R. H. Dicke, Phys. Rev. 93, 99 (1954).
4. Q. Zhang et al., Phys. Rev. Lett. 113, 047601 (2014).
5. Q. Zhang et al., Nat. Phys. 12, 1005 (2016).
6. X. Li et al., Nat. Photon. 12, 324 (2018).
7. X. Li et al., Science 361, 794 (2018).
8. D. Kim et al., Sci. Adv. 11, eadt1691 (2025).
