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K Sacha

Publications and source records attributed to K Sacha.

3 recordsLinked to original sources

Routes towards Anderson-like localization of Bose-Einstein condensates in disordered optical lattices.

We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.

Journal Article↗

Driven Rydberg atoms reveal quartic level repulsion.

The dynamics of Rydberg states of a hydrogen atom subjected simultaneously to uniform static electric field and two microwave fields with commensurate frequencies is considered in the range of small field amplitudes. In the certain range of the parameters of the system the classical secular motion of the electronic ellipse reveals chaotic behavior. Quantum mechanically, when the fine structure of the atom is taken into account, the energy level statistics obey predictions appropriate for the symplectic Gaussian random matrix ensemble.

Journal Article↗

Massive haemorrhage presenting as a complication after percutaneous nephrolithotomy (PCNL).

Authors describe and discuss cases of massive haemorrhage after percutaneous nephrolithotomy. In 10 (0.3%) of 3080 patients who underwent PCNL massive haemorrhage from renal fistula drain or urinary bladder was observed. Renal arteriography was performed in this group of patients which revealed arteriovenous fistulae in 4 patients and aneurysms of renal artery branches in 2. In 4 patients arteriography did not reveal haemorrhage. In one patient nephrectomy was necessary to stop the haemorrhage.

Arteriovenous Fistula↗