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A Nazarkin

Publications and source records attributed to A Nazarkin.

7 recordsLinked to original sources
PubMed2004

High-order Raman scattering of X rays by optical phonons and generation of ultrafast X-ray transients.

We study the modulation of x-ray diffraction in ideal crystals by a copropagating wave of optical vibrations generated by a fs-laser pulse. Our results suggest that in the synchronous interaction regime the output diffracted x-ray field has the form of ultrafast transients with a time structure even shorter than the period of the excited vibrational mode. The behavior is explained in terms of high-order Raman scattering of x rays by optical phonons.

Optics and Photonics↗
PubMed2004

Electromagnetically induced quantum memory.

We discuss the problem of creating coherence in an optically driven quantum system in conditions where decoherence is caused by the laser field itself, due to coupling of the system to a rapidly decaying state or continuum. It is shown that by applying an additional laser field between this state and a bound state the relaxation channel can be suppressed as a result of a "dark state" formation, giving rise to long living Rabi oscillations in the system. It is found that the same mechanism of preserving coherence exists in systems with level splitting or degeneracy, where the driving field interacts with multiple resonant sublevels simultaneously. We also show that specific coherent propagation phenomena assisted by the interference suppression of decoherence can be observed under these conditions.

Journal Article↗
PubMed2003

Observation of selectivity of coherent population transfer induced by optical interference.

A fs time-resolved selective control of multilevel systems using superposition of two identical, frequency-chirped fields is proposed and demonstrated. By adjusting the delay between the pulses, a selected transition of the Rb doublet was brought into the "holes" of the interference pattern and remained nonexcited, thus allowing to manipulate another transition by the laser field as if it were an isolated two-level system. Based on light interference, this technique needs neither strong driving field intensities nor controlling the chirp direction to achieve the selectivity.

Journal Article↗
PubMed2000

fs-pulse synthesis using phase modulation by impulsively excited molecular vibrations

We report the temporal characteristics of laser radiation transmitted through impulsively excited SF6 and exhibiting sideband Raman lines. Even without special dispersion control we observed a sequence of compressed fs pulses following with the period of the excited A(1g) vibrational mode of SF6. The use of both negative and positive group velocity dispersion compensation for the temporal compression was found to be as appropriately efficient. The results prove our new concept of the ultrafast molecular phase modulator.

Journal Article↗