Biomedical subjects

Y Kagan

Publications and source records attributed to Y Kagan.

8 recordsLinked to original sources

PubMed2001

Energy transport induced by an external alternating field in strongly disordered media.

The delocalization of excitations in an ensemble of two-level systems with a strong disorder due to an external alternating acoustic or electric field is considered. The propagating modes are shown to appear if a ratio of the field amplitude to the frequency is large enough. Two complementary approaches, the static one similar to that of Anderson and the dynamic one related to Landau-Zener, are developed. It is shown that the field-induced relaxation mechanism can have a strong influence on the kinetics. The internal friction is argued to be vastly affected by the relaxation mechanism proposed.

Journal Article↗

PubMed2000

Manifestation of superfluidity in an evolving Bose-Einstein condensed gas.

We study the generation of excitations due to an "impurity" (static perturbation) placed into an oscillating Bose-Einstein condensed gas in the time-dependent trapping field. It is shown that there are two regions for the position of the local perturbation. In the first region the condensate flows around the impurity without generation of excitations demonstrating superfluid properties. In the second region the creation of excitations occurs, at least within a limited time interval, revealing destruction of superfluidity. The phenomenon can be studied by measuring the damping of condensate oscillations at different positions of the impurity.

Journal Article↗

PubMed1996