RESUMEN
We investigate the laser-induced quantum interference in extreme ultraviolet superfluorescence (SF) occurring in a dense gas of Λ-type helium atoms coupled by a coherent laser field in the visible region. Due to the constructive interatomic and intraatomic interferences, the SF can split in two pulses conveniently controlled by the gas density and intensity of the driving field, suggesting potential applications for pump-probe experiments.
RESUMEN
A method is investigated to manipulate the annihilation dynamics of a dense gas of positronium atoms employing superradiance and subradiance regimes of the cooperative spontaneous emission of the system. The corresponding annihilation dynamics is explored in two setups with regard to its fundamental novel properties and controlled by the gas density and by the intensity of a driving strong resonant laser field. In particular, the method allows us to increase the annihilation lifetime of an ensemble of positronium atoms by trapping the atoms in the excited state via collective radiative effects in the resonant laser field. In the second setup, the effect is enhanced by employing a cavity field. The maximum lifetime increase is by a factor of about 200 for para-positronium and by a factor of about 100 for ortho-positronium.
RESUMEN
We demonstrate that a single subcycle optical pulse can be generated when a pulse with a few optical cycles penetrates through resonant two-level dense media with a subwavelength structure. The single-cycle gap soliton phenomenon in the full Maxwell-Bloch equations without the frame of the slowly varying envelope and rotating wave approximations is observed. Our study shows that the subwavelength structure can be used to suppress the frequency shift caused by intrapulse four-wave mixing in continuous media and supports the formation of single-cycle gap solitons even in the case when the structure period breaks the Bragg condition. This suggests a way toward shortening high-intensity laser fields to few- and even single-cycle pulse durations.
RESUMEN
Light scattered by a regular structure of atoms can exhibit interference signatures, similar to the classical double-slit. These first-order interferences, however, vanish for strong light intensities, restricting potential applications. Here, we show how to overcome these limitations to quantum interference in strong fields. First, we recover the first-order interference in strong fields via a tailored electromagnetic bath with a suitable frequency dependence. At strong driving, the optical properties for different spectral bands are distinct, thus extending the set of observables. We further show that for a two-photon detector as, e.g., in lithography, increasing the field intensity leads to twice the spatial resolution of the second-order interference pattern compared to the weak-field case.
RESUMEN
The manipulation of the steady-state behavior of a collection of dipole-interacting three-level atoms in a V or Lambda configuration is investigated as a function of the relative phase of two strong coherent driving fields. For larger samples, the phase is shown to be a convenient parameter to rapidly populate or depopulate completely a trapping state of the ensemble. As applications, we present the appropriately prepared atomic sample as an optical switching device and show its virtues in controlling the collective steady-state resonance fluorescence intensity.
