arXiv subjects

A. V. Rybin

Publications and source records attributed to A. V. Rybin.

9 recordsLinked to original sources

arXiv2006

Slow-light solitons: influence of relaxation

We have applied the transformation of the slow light equations to Liouville theory that we developed in our previous work, to study the influence of relaxation on the soliton dynamics. We solved the problem of the soliton dynamics in the presence of relaxation and found that the spontaneous emission from the upper atomic level is strongly suppressed. Our solution proves that the spatial shape of the soliton is well preserved even if the relaxation time is much shorter than the soliton time length. This fact is of great importance for applications of the slow-light soliton concept in optical information processing. We also demonstrate that the relaxation plays a role of resistance to the soliton motion and slows the soliton down even if the controlling field is constant.

quant-ph↗

arXiv2006

Slow-light solitons revisited

We investigate propagation of slow-light solitons in atomic media described by the nonlinear $Λ$-model. Under a physical assumption, appropriate to the slow light propagation, we reduce the $Λ$-scheme to a simplified nonlinear model, which is also relevant to 2D dilatonic gravity. Exact solutions describing various regimes of stopping slow-light solitons can then be readily derived.

quant-ph↗

arXiv2005

Theory of slow-light solitons

In the framework of the nonlinear $Λ$-model we investigate propagation of solitons in atomic vapors and Bose-Einstein condensates. We show how the complicated nonlinear interplay between fast solitons and slow-light solitons in the $Λ$-type media points to the possibility to create optical gates and, thus, to control the optical transparency of the $Λ$-type media. We provide an exact analytic description of decelerating, stopping and re-accelerating of slow-light solitons in atomic media in the nonadiabatic regime. Dynamical control over slow-light solitons is realized via a controlling field generated by an auxiliary laser. For a rather general time dependence of the field; we find the dynamics of the slow-light soliton inside the medium. We provide an analytical description for the nonlinear dependence of the velocity of the signal on the controlling field. If the background field is turned off at some moment of time, the signal stops. We find the location and shape of the spatially localized memory bit imprinted into the medium. We discuss physically interesting features of our solution, which are in a good agreement with recent experiments.

quant-ph↗

arXiv2005

An exact solution of the slow-light problem

We investigate propagation of a slow-light soliton in atomic vapors and Bose-Einstein condensates described by the nonlinear Lambda-model. We show that the group velocity of the soliton monotonically decreases with the intensity of the controlling laser field, which decays exponentially after the laser is switched off. The shock wave of the vanishing controlling field overtakes the slow soliton and stops it, while the optical information is recorded in the medium in the form of spatially localized polarization. We find an explicit exact solution describing the whole process within the slowly varying amplitude and phase approximation. Our results point to the possibility of addressing spatially localized memory formations and moving these memory bits along the medium in a controllable fashion.

quant-ph↗

arXiv2005

Manipulation of optical memory bits in atomic vapors and Bose-Einstein condensates

We provide an exact analytic description of decelerating, stopping and re-accelerating optical solitons in atomic media. By virtue of this solution we describe in detail how spatially localized optical memory bits can be written down, read and moved along the atomic medium in a prescribed manner. Dynamical control over the solitons is realized via a background laser field whose intensity controls the velocity of the slow light in a similar way as in the linear theory of electromagnetically induced transparency (EIT). We solve the nonlinear model when the controlling field and the solitons interact in an inseparable nonlinear superposition process. This allows us to access results beyond the limits of the linear theory of EIT.

quant-ph↗

arXiv2004

Driving the slow-light soliton by controlling laser field

In the framework of the nonlinear $Λ$-model we investigate propagation of a slow-light soliton in atomic vapors and Bose-Einstein condensates. The velocity of the slow-light soliton is controlled by a time-dependent background field created by a controlling laser. For a fairly arbitrary time dependence of the field we find the dynamics of the slow-light soliton inside the medium. We provide an analytical description for the nonlinear dependence of the velocity of the signal on the controlling field. If the background field is turned off at some moment of time, the signal stops. We find the location and shape of the spatially localized memory bit imprinted into the medium. We show that the process of writing optical information can be described in terms of scattering data for the underlying scattering problem.

quant-ph↗

arXiv2004

Manipulation of optical solitons in Bose-Einstein condensates

We propose a method to control the optical transparency of a Bose-Einstein condensate with working energy levels of the Lambda-type. The reported effects are essentially nonlinear and are considered in the framework of an exactly solvable model describing the interaction of light with a Lambda-type medium. We show how the complicated nonlinear interplay between fast and slow solitons in the $Λ$-type medium points to a possibility to create optical gates as well as to a possibility to store optical information.

quant-ph↗

arXiv2002

Singularity formation in the Gross-Pitaevskii Equation and Collapse in BEC

We study a mechanism of collapse of the condensate wave function in the Gross-Pitaevskii theory with attractive interparticle interaction. We reformulate the Gross-Pitaevskii equation as Newton's equations for the particle flux and introduce a collapsing fraction of particles. We assume that the collapsing fraction is expelled from the condensate due to dissipation. Using this hypothesis we analyze the dependence of the condensate collapse on the initial conditions. We found that for a properly chosen negative scattering length the remnant fraction becomes larger when the initial aspect ratio is increased.

cond-mat↗

arXiv2001

Singularity Formation and Collapse in the Attractive Gross-Pitaevskii Equation

A generic mechanism of collapse in the Gross-Pitaevskii equation with attractive interparticle interactions is gained by reformulating this equation as Newton's equation of motion for a system of particles with a constraint. 'Quantum pressure' effects give rise to formation of a potential barrier around the emerging singularity, which prevents a fraction of the particles from falling into the singularity. For reasonable initial widths of the condensate, the fraction of collapsing particles, which are thereby removed from the condensate, is found to be a 'universal' number $\simeq 0.7$.

cond-mat↗