The effect of light-matter interaction is investigated for a situation where counter propagating ... more The effect of light-matter interaction is investigated for a situation where counter propagating laser pulses of localized nature are incident on the atomic condensate. In contrast to the earlier investigations on the similar systems, it's assumed that the laser beams are ultra-fast and they have a $\mathrm{sech}^2$ profile. Specifically, we consider a quasi-homogeneous, later extended to inhomogeneous, Bose-Einstein condensate (BEC), which is exposed to two counter propagating orthogonally polarized ultra-fast laser beams of equal intensity. The electromagnetic field creates an optical potential for the Bose-Einstein condensate, which in turn modifies the optical field. Hence, light and matter are found to contentiously exchange energy and thus to modify themselves dynamically. In the inhomogenous case, a self-similar method is used here to treat a cigar-shaped BEC exposed to light. Our theoretical analysis in a hither to unexplored regime of BEC-light interaction hints at the ...
Exchange of energy by means of light-matter interaction provides a new dimension to various nonli... more Exchange of energy by means of light-matter interaction provides a new dimension to various nonlinear dynamical systems. Here, the effects of light-matter interaction are investigated for a situation, where two counter-propagating, orthogonally polarized laser pulses are incident on the atomic condensate. It's observed that a localized laser pulse profile can induce localized modes in Bose-Einstein condensate. A stability analysis performed using Vakhitov-Kolokolov-like criterion has established that these localized modes are stable, when the atom-atom interaction is repulsive. The cooperative effects of light-matter interactions and atom-atom interactions on the Lieb-mode have been studied in the stable region through atomic dispersion, revealing the signature of bound state formation when the optical potential is Pöschl-Teller type. The energy diagram also indicates a continuous transfer of energy from the laser pulses to the atoms as the light-matter interaction changes its sign. PACS. 03.75.Lm Bose-Einstein condensates in periodic potentials-05.45.Yv SOlitons-32.80.Qk Coherent control of atomic interactions with photons
In this work, we realize the soliton's negative mass regime, when a Bose-Einstein condensate is s... more In this work, we realize the soliton's negative mass regime, when a Bose-Einstein condensate is subjected to a harmonic confinement. We also discuss that this system is favorable for the formation of a bound state when an additional species is considered. When a time modulated optical lattice potential is introduced, the sinusoidal lattice modes lead to the generation of nonlinear resonances. A classical dynamical phase transition is also identified in this case through a superfluid to the insulating phase transition.
We study the dispersion mechanism of Lieb mode excitations of both single and multi component ult... more We study the dispersion mechanism of Lieb mode excitations of both single and multi component ultra-cold atomic Bose gas, subject to a harmonic confinement through chirp management. It is shown that in some parameter domain, the hole-like excitations lead to the soliton's negative mass regime, arising due to the coupling between chirp momentum and Kohn mode. In low momenta region the trap considerably affects the dispersion of the grey soliton, which opens a new window to observe Lieb-mode excitations. Further, we extend our analysis to binary condensate, which yields usual shape compatible grey-bright soliton pairs. The inter-species interaction induces a shift in the Lieb-mode excitations, where the pair can form a bound state. We emphasize that the present model provides an opportunity to study such excitations in the low momenta regime, as well as the formation of bound state in binary condensate.
Journal of Physics B: Atomic, Molecular and Optical Physics, 2013
We demonstrate the existence of supersonic bell soliton in the Bardeen-Cooper-Schrieffer-Bose-Ein... more We demonstrate the existence of supersonic bell soliton in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensate (BCS-BEC) crossover regime. Starting from the extended Thomas-Fermi density functional theory of superfluid order parameter, a density transformation is used to map the hydrodynamic mean field equation to a Lienard type equation. As a result, bell solitons are obtained as exact solutions, which is further verified by the numerical solution of the dynamical equation. The stability of the soliton is established and its behavior in the entire crossover domain is obtained. It is found that, akin to the case of vortices, the bell solitons yield highest contrast in the BEC regime.
We elaborate on a general method to find complex envelope solitons in a cigar shaped Bose-Einstei... more We elaborate on a general method to find complex envelope solitons in a cigar shaped Bose-Einstein condensate in a trap. The procedure incorporates time dependent scattering length, oscillator frequency and loss/gain. A variety of time dependencies of the above parameters, akin to the ones occurring in the experiments can be tackled.
Experimentally observed grey solitons are analytically extracted from a physically viable Gross-P... more Experimentally observed grey solitons are analytically extracted from a physically viable Gross-Pitaevskii equation. Associated Lieb and Bogoliubov modes are calculated for these class of solitons. It is observed that, these nonlinear excitations have strong coupling with the trap at low momenta and hence can be effectively isolated from the Bogoliubov sound modes, which responds weakly to harmonic confinement. This strong coupling with the trap also makes the grey soliton amenable for control and manipulation through both trap modulation and temporal variation of the two-body interaction.
The effect of light-matter interaction is investigated for a situation where counter propagating ... more The effect of light-matter interaction is investigated for a situation where counter propagating laser pulses of localized nature are incident on the atomic condensate. In contrast to the earlier investigations on the similar systems, it's assumed that the laser beams are ultra-fast and they have a $\mathrm{sech}^2$ profile. Specifically, we consider a quasi-homogeneous, later extended to inhomogeneous, Bose-Einstein condensate (BEC), which is exposed to two counter propagating orthogonally polarized ultra-fast laser beams of equal intensity. The electromagnetic field creates an optical potential for the Bose-Einstein condensate, which in turn modifies the optical field. Hence, light and matter are found to contentiously exchange energy and thus to modify themselves dynamically. In the inhomogenous case, a self-similar method is used here to treat a cigar-shaped BEC exposed to light. Our theoretical analysis in a hither to unexplored regime of BEC-light interaction hints at the ...
Exchange of energy by means of light-matter interaction provides a new dimension to various nonli... more Exchange of energy by means of light-matter interaction provides a new dimension to various nonlinear dynamical systems. Here, the effects of light-matter interaction are investigated for a situation, where two counter-propagating, orthogonally polarized laser pulses are incident on the atomic condensate. It's observed that a localized laser pulse profile can induce localized modes in Bose-Einstein condensate. A stability analysis performed using Vakhitov-Kolokolov-like criterion has established that these localized modes are stable, when the atom-atom interaction is repulsive. The cooperative effects of light-matter interactions and atom-atom interactions on the Lieb-mode have been studied in the stable region through atomic dispersion, revealing the signature of bound state formation when the optical potential is Pöschl-Teller type. The energy diagram also indicates a continuous transfer of energy from the laser pulses to the atoms as the light-matter interaction changes its sign. PACS. 03.75.Lm Bose-Einstein condensates in periodic potentials-05.45.Yv SOlitons-32.80.Qk Coherent control of atomic interactions with photons
In this work, we realize the soliton's negative mass regime, when a Bose-Einstein condensate is s... more In this work, we realize the soliton's negative mass regime, when a Bose-Einstein condensate is subjected to a harmonic confinement. We also discuss that this system is favorable for the formation of a bound state when an additional species is considered. When a time modulated optical lattice potential is introduced, the sinusoidal lattice modes lead to the generation of nonlinear resonances. A classical dynamical phase transition is also identified in this case through a superfluid to the insulating phase transition.
We study the dispersion mechanism of Lieb mode excitations of both single and multi component ult... more We study the dispersion mechanism of Lieb mode excitations of both single and multi component ultra-cold atomic Bose gas, subject to a harmonic confinement through chirp management. It is shown that in some parameter domain, the hole-like excitations lead to the soliton's negative mass regime, arising due to the coupling between chirp momentum and Kohn mode. In low momenta region the trap considerably affects the dispersion of the grey soliton, which opens a new window to observe Lieb-mode excitations. Further, we extend our analysis to binary condensate, which yields usual shape compatible grey-bright soliton pairs. The inter-species interaction induces a shift in the Lieb-mode excitations, where the pair can form a bound state. We emphasize that the present model provides an opportunity to study such excitations in the low momenta regime, as well as the formation of bound state in binary condensate.
Journal of Physics B: Atomic, Molecular and Optical Physics, 2013
We demonstrate the existence of supersonic bell soliton in the Bardeen-Cooper-Schrieffer-Bose-Ein... more We demonstrate the existence of supersonic bell soliton in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensate (BCS-BEC) crossover regime. Starting from the extended Thomas-Fermi density functional theory of superfluid order parameter, a density transformation is used to map the hydrodynamic mean field equation to a Lienard type equation. As a result, bell solitons are obtained as exact solutions, which is further verified by the numerical solution of the dynamical equation. The stability of the soliton is established and its behavior in the entire crossover domain is obtained. It is found that, akin to the case of vortices, the bell solitons yield highest contrast in the BEC regime.
We elaborate on a general method to find complex envelope solitons in a cigar shaped Bose-Einstei... more We elaborate on a general method to find complex envelope solitons in a cigar shaped Bose-Einstein condensate in a trap. The procedure incorporates time dependent scattering length, oscillator frequency and loss/gain. A variety of time dependencies of the above parameters, akin to the ones occurring in the experiments can be tackled.
Experimentally observed grey solitons are analytically extracted from a physically viable Gross-P... more Experimentally observed grey solitons are analytically extracted from a physically viable Gross-Pitaevskii equation. Associated Lieb and Bogoliubov modes are calculated for these class of solitons. It is observed that, these nonlinear excitations have strong coupling with the trap at low momenta and hence can be effectively isolated from the Bogoliubov sound modes, which responds weakly to harmonic confinement. This strong coupling with the trap also makes the grey soliton amenable for control and manipulation through both trap modulation and temporal variation of the two-body interaction.
Uploads
Papers by Ayan Khan