arXiv subjects

Priyam Das

Publications and source records attributed to Priyam Das.

39 records · Page 3Linked to original sources

arXiv2010

Effect of an Impurity on Grey Soliton Dynamics in Cigar-Shaped Bose-Einstein Condensate

In a cigar shaped Bose-Einstein condensate, explicit solutions of the coupled mean-field equations, describing defect-grey soliton dynamics are obtained, demonstrating the coexistence of grey soliton and a localized defect. Unlike the case of dark soliton, where the defect trapping center has vanishing superfluid density, the moving grey soliton necessarily possesses a finite superfluid component at the defect location. The wave vector of the impurity is controlled by the velocity of the grey soliton, which has an upper bound. It is found that the presence of the impurity lowers the speed of the grey soliton, as compared to the defect free case, where it can reach the sound velocity. The grey soliton's energy gets substantially modified through its interaction with the defect, opening up the possibility of its control through defect dynamics.

cond-mat.quant-gas↗

arXiv2010

Loss of superfluidity in the Bose-Einstein condensate in an optical lattice with cubic and quintic nonlinearity

In a one-dimensional shallow optical lattice, in the presence of both cubic and quintic nonlinearity, a superfluid density wave is identified in a Bose-Einstein condensate. Interestingly, it ceases to exist when only one of these interactions is operative. We predict the loss of superfluidity through a classical dynamical phase transition, where modulational instability leads to the loss of phase coherence. In a certain parameter domain, the competition between lattice potential and the interactions is shown to give rise to a stripe phase, where atoms are confined in finite domains. In a pure two-body case, apart from the known superfluid and insulating phases, a density wave insulating phase is found to exist, possessing two frequency modulations commensurate with the lattice potential.

cond-mat.other↗

arXiv2009

Sinusoidal Excitations in Two Component Bose-Einstein Condensates

The non-linear coupled Gross-Pitaevskii equation governing the dynamics of the two component Bose-Einstein condensate (TBEC) is shown to admit pure sinusoidal, propagating wave solutions in quasi one dimensional geometry. These solutions, which exist for a wide parameter range, are then investigated in the presence of a harmonic oscillator trap with time dependent scattering length. This illustrates the procedure for coherent control of these modes through temporal modulation of the parameters, like scattering length and oscillator frequency. We subsequently analyzed this system in an optical lattice, where the occurrence of an irreversible phase transition from superfluid to insulator phase is seen.

cond-mat.other↗