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Yu. V. Bezvershenko

Publications and source records attributed to Yu. V. Bezvershenko.

2 recordsLinked to original sources

The fate of a gray soliton in a quenched Bose-Einstein condensate

We investigate the destiny of a gray soliton in a repulsive one-dimensional Bose-Einstein condensate undergoing a sudden quench of the non-linearity parameter. The outcome of the quench is found to depend dramatically on the ratio $η$ of the final and initial values of the speed of sound. For integer $η$ the soliton splits into exactly $2η-1$ solitons. For non-integer $η$ the soliton decays into multiple solitons and Bogoliubov modes. The case of integer $η$ is analyzed in detail. The parameters of solitons in the out-state are found explicitly. Our approach exploits the inverse scattering method and can be easily used for the similar quenches in any classical integrable system.

cond-mat.quant-gas

Resonance in a driven two-level system: analytical results without the rotating wave approximation

We consider the problem of two-level system dynamics induced by the time-dependent field B={a(t)cosωt,a(t)sinωt,ω_0}, with a(t) \sim cn(νt,k). The problem is exactly analytically solvable and we propose the scheme for constructing the solutions. For all field configurations the resonance conditions are discussed. The explicit solutions for N=1,2 we obtained coincide at ω=0 in the proper parameter domain with predictions of the rotating wave approximation and agree nicely with numerical calculations beyond it.

math-ph