Time behavior of superradiance

Hideaki Hara, Riku Omoto, N. Sasao +6 more

To achieve more controllable development of coherence in solids, we investigated the effect of a trigger laser tuned to the superradiance transition wavelength on periodic superradiance observed in an Er:YSO crystal. For period control, applying the trigger laser reduced both the superradiance period and its variance, demonstrating enhanced controllability of coherence development dynamics. As the trigger laser power increased, both the period and the number of emitted superradiance photons decreased while maintaining a proportional relationship. This behavior is explained by a reduced superradiance threshold under a constant excitation rate and is reproduced by numerical simulations based on the Maxwell-Bloch equations. For timing control, we found that superradiance could be triggered even when the excitation laser alone was insufficient. This enabled us to control the emission timing of superradiance using short trigger pulses and provided a device capable of generating superradiance at desired timing.

Masuo Suzuki

L. I. Men’shikov

Christoph M. Greiner, THOMAS W. MOSSBERG

Summary form only given. The radiative behavior of an ensemble of correlated atoms can be dramatically different from that of a single atom. Correlation, for example, can give rise to sub- or superradiant emission. Experimental studies of the fascinating correlative effects expected have been severely constrained by difficulties in creating suitably correlated media and by propagation effects that perturb correlation during emission. We have found that optical cavities of moderate reflectivity and very short ring-down time can be employed to "accelerate" the superradiant process and bring it to dominance in media sufficiently dilute so that propagation effects both in excitation and emission are absent. For the first time, it is possible to observe strong optical superradiance under the pure and simple conditions that were originally envisioned. Note that superradiance here does not refer to the emission of initially inverted atomic samples (i.e. superfluorescence), but to cooperative emission from samples of atoms prepared in correlated superposition states. Moreover, the cavity accelerated superradiant system is found to display heretofore unknown nonlinear behavior in terms of its effect on the "area" of injected optical pulses.

L. M. Biberman, А. И. Глейзер, Г. А. Кобзев

Oriol Rubies-Bigordà, Susanne F. Yelin

Superradiance and subradiance are collective effects that emerge from coherent interactions between quantum emitters. Due to their many-body nature, theoretical studies of extended samples with length larger than the atomic transition wavelength are usually restricted to their early-time behavior or to the few-excitation limit. We use herein a mean-field approach to reduce the complex many-body system to an effective two-atom master equation that includes all correlations up to second order and that can be numerically propagated in time. We find that three-dimensional and two-dimensional inverted atomic arrays sustain superradiance below a critical lattice spacing and quantify the scaling of the superradiant peak for both dimensionalities. Finally, we study the late-time dynamics of the system and demonstrate that a subradiant phase appears before the system finally relaxes.