Spontaneous emission with a cascaded driving field in the same transition channel

D. V. Skobelʹt︠s︡yn

Piotr Gładysz, Karolina Słowik, Francesco V. Pepe

We investigate spontaneous radiative processes in a driven polar two-level system whose interaction with the laser field is dominated by broken inversion symmetry rather than by the usual transition dipole coupling. Using a polaron transformation, we derive the dressed eigenstates of the atom-laser system and show that their longitudinal coupling reshapes the spectrum into two displaced harmonic ladders. We then analyze spontaneous transitions induced by a bosonic reservoir, and obtain transition rates that depend on both the laser parameters and the overlap between displaced field states. In the few-photon regime, we identify conditions under which spontaneous emission from the excited state can be strongly suppressed, thereby extending its lifetime, as well as regimes where the ladder structure enables spontaneous absorption from the ground state. In the semiclassical limit of a strong coherent drive, we derive compact analytical expressions for the total transition rates and show that they are governed by Bessel-function weights associated with multiphoton channels. Our results show how broken inversion symmetry qualitatively modifies decay dynamics and radiative cascades, and they establish driven polar quantum systems as a platform for controlling spontaneous light emission beyond the standard inversion-symmetric setting.

G. S. Agarwal, János A. Bergou, Claus Benkert +1 more

An intense single-mode correlated-spontaneous-emission laser or maser can be realized by driving the active atoms coherently with an injected external field. The scheme involves single-photon transitions unlike the two-photon or quantum-beat correlated-emission lasers that utilize correlations between successive photon-cascade emissions or between simultaneous emissions into modes of the field. Quenching of both the amplitude and phase noise and, in certain cases, squeezing of the amplitude fluctuations are found.

Takasi Endo

Xiangming Hu, Wenxing Shi, Qing Yang Xu +3 more

Mihai Macovei, Jörg Evers, Christoph H. Keitel

The spontaneous emission of an excited two-level emitter driven by a strong classical coherent low-frequency electromagnetic field is investigated. We find that for relatively strong laser driving, multiphoton processes are induced, thereby opening additional decay channels for the atom. We analyze the interplay between the strong low-frequency driving and the interfering multiphoton decay channels, and discuss its implications for the spontaneous emission dynamics.