-
[show abstract]
[hide abstract]
ABSTRACT: We report here the experimental observation of an ultranarrow resonance, as narrow as EIT ones, due to the transfer of coherent population oscillations to the lower states of a Λ-system.
Frontiers in Optics (FiO), Rochester, NY; 09/2012
-
[show abstract]
[hide abstract]
ABSTRACT: It is well known that ultranarrow electromagnetically induced transparency (EIT) resonances can be observed in atomic gases at room temperature. We report here the experimental observation of another type of ultranarrow resonances, as narrow as the EIT ones, in a \Lambda-system selected by light polarization in metastable 4He at room temperature. It is shown to be due to coherent population oscillations in an open two-level system (TLS). For perpendicular linearly polarized coupling and probe beams, this system can be considered as two coupled open TLSs, in which the ground state populations exhibit anti-phase oscillations. We also predict theoretically that in case of two parallel polarizations, the system would behave like a closed TLS, and the narrow resonance associated with these oscillations would disappear.
----. 01/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: It is well known that ultranarrow electromagnetically induced transparency (EIT) resonances can be observed in atomic gases at room temperature. We report here the experimental observation of another type of ultranarrow resonances, as narrow as the EIT ones, in a �-system selected by light polarization in metastable 4He at room temperature. It is shown to be due to coherent population oscillations in an open two-level system (TLS). For perpendicular linearly polarized coupling and probe beams, this system can be considered as two coupled open TLSs, in which the ground state
populations exhibit anti-phase oscillations. We also predict theoretically that in case of two parallel polarizations, the system would behave like a closed TLS, and the narrow resonance associated with these oscillations would disappear.
arXiv:1201.3742[physics.atom-ph]. 01/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: Propagation of light pulses through negative group velocity media is known to
give rise to a number of paradoxical situations that seem to violate causality.
The solution of these paradoxes has triggered the investigation of a number of
interesting and unexpected features of light propagation. Here we report a
combined theoretical and experimental study of the ring-down oscillations in
optical cavities filled with a medium with such a strongly negative frequency
dispersion to give a negative round-trip group delay time. We theoretically
anticipate that causality imposes the existence of additional resonance peaks
in the cavity transmission, resulting in a non-exponential decay of the cavity
field and in a breakdown of the cavity decay rate concept. Our predictions are
validated by simulations and by an experiment using a room-temperature gas of
metastable helium atoms in the detuned electromagnetically induced transparency
regime as the cavity medium.
07/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: The quantum coherence phenomenon of electromagnetically induced transparency (EIT) is observed in a three-level system composed of an excited state and two coherent superpositions of the two ground-state levels. This peculiar ground state basis is composed of the so-called bright and dark states of the same atomic system in a standard coherent population trapping configuration. The characteristics of EIT, namely, width of the transmission window and reduced group velocity of light, in this unusual basis, are theoretically and experimentally investigated and are shown to be essentially identical to those of standard EIT in the same system.
Optics Express 10/2009; 17(22):19444-50. · 3.59 Impact Factor
