1. Condensation of vanishing photon emission rates in random atomic clouds
- Author
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Viggiano, Viviana, Bachelard, Romain, Cunden, Fabio Deelan, Facchi, Paolo, Kaiser, Robin, Pascazio, Saverio, Pepe, Francesco V., and Scardicchio, Antonello
- Subjects
Quantum Physics ,Condensed Matter - Quantum Gases ,Mathematical Physics - Abstract
In the collective photon emission from atomic clouds both the atomic transition frequency and the decay rate are modified compared to a single isolated atom, leading to the effects of superradiance and subradiance. In this Letter, we analyse the properties of the Euclidean random matrix associated to the radiative dynamics of a cold atomic cloud, previously investigated in the contexts of photon localization and Dicke super- and subradiance. We present evidence of a new type of phase transition, surprisingly controlled by the cooperativeness parameter, rather than the spatial density or the diagonal disorder. The numerical results corroborate the occurrence of such a phase transition at a critical value of the cooperativeness parameter, above which the lower edge of the spectrum vanishes exhibiting a macroscopic accumulation of eigenvalues. Independent evaluations based on the two phenomena provide the same value of the critical cooperativeness parameter., Comment: 8 pages, 6 figures
- Published
- 2024