Enhancement of Kerr nonlinearity via multi-photon coherence

We propose a new method of resonant enhancement of optical Kerr nonlinearity using multi-level atomic coherence. The enhancement is accompanied by suppression of the other linear and nonlinear susceptibility terms of the medium. We show that the effect results in a modification of the nonlinear Faraday rotation of light propagating in an Rb87 vapor cell by changing the ellipticity of the light.Comment: 4 pages, 3 figures Submitted to Optics Letter

El infoentretenimiento en la televisión rusa como medio para desacralizar los mitos soviéticos y crear un mito sobre el futuro

This paper deals with the process of incorporation of “infotainment” in the Russian television industry. Professional journalism is analyzed as a tool for the interpretation of facts, which have contributed to erode the myths of mass consciousness, which were formed by Soviet propaganda. According to the author, television news and other infotainment programs have affected socio-cultural processes in Russia; in particular, they have contributed to shaping the worldview of post-Soviet intellectuals, known as the “new intelligentsia”.Este artículo trata principalmente el proceso de incorporación del “infoentretenimiento” en la industria televisiva rusa. El periodismo profesional se considera como un medio para la interpretación de los hechos que ha contribuido a erosionar los mitos de la conciencia de masas configurados por la propaganda soviética. Según la hipótesis defendida por la autora, las noticias de televisión y otros programas de infoentretenimiento han influido notablemente en procesos socio-culturales en Rusia, en concreto, en la formación de la visión del mundo de los intelectuales post-soviéticos, también llamados la “nueva intelectualidad”

Persistence-driven durotaxis: Generic, directed motility in rigidity gradients

Cells move differently on substrates with different elasticities. In particular, the persistence time of their motion is higher on stiffer substrates. We show that this behavior will result in a net transport of cells directed up a soft-to-stiff gradient. Using simple random walk models with controlled persistence and stochastic simulations, we characterize this propensity to move in terms of the durotactic index measured in experiments. A one-dimensional model captures the essential features of this motion and highlights the competition between diffusive spreading and linear, wavelike propagation. Since the directed motion is rooted in a non-directional change in the behavior of individual cells, the motility is a kinesis rather than a taxis. Persistence-driven durokinesis is generic and may be of use in the design of instructive environments for cells and other motile, mechanosensitive objects.Comment: 5 pages, 4 figure

Observation of polarization quantum noise of laser radiation in Rb vapor cell

We present experimental study of polarization quantum noise of laser radiation passed through optically think vapor of Rb87. We observe a step-like noise spectrum. We discuss various factor which may result in such noise spectrum and prevent observation of squeezing of quantum fluctuations predicted in Matsko et al. PRA 63, 043814 (2001).Comment: 4 pages, 5 figures. Translated from Russian by I. Novikov

Radiation trapping in coherent media

We show that the effective decay rate of Zeeman coherence, generated in a Rb87 vapor by linearly polarized laser light, increases significantly with the atomic density. We explain this phenomenon as the result of radiation trapping. Our study shows that radiation trapping must be taken into account to fully understand many electromagnetically induced transparency experiments with optically thick media

Large negative and positive delay of optical pulses in coherently prepared dense Rb vapor with buffer gas

We experimentally study the group time delay for a light pulse propagating through hot Rb vapor in the presence of a strong coupling field in a $\Lambda$ configuration. We demonstrate that the ultra-slow pulse propagation is transformed into superluminal propagation as the one-photon detuning of the light increases due to the change in the transmission resonance lineshape. Negative group velocity as low as -c/10^6=-80 m/s is recorded. We also find that the advance time in the regime of the superluminal propagation grows linearly with increasing laser field power.Comment: 5 pages, 6 figure