arXiv subjects

Vivek M. Vyas

Publications and source records attributed to Vivek M. Vyas.

24 records · Page 2Linked to original sources

arXiv2011

On Berezinskii-Kosterlitz-Thouless Phase Transition in Quasi-One Dimensional Bose-Einstein Condensate

We show that quasi-one dimensional Bose-Einstein condensate under suitable conditions can exhibit a Berezinskii-Kosterlitz-Thouless phase transition. The role played by quantized vortices in two dimensional case, is played in this case by dark solitons. We find that the critical temperature for this transition lies in nano Kelvin range and below, for a wide range of experimentally accessible parameters. It is seen that the high temperature (disordered) phase differs from low temperature (ordered) phase in terms of phase coherence, which can be used as an experimental signature for observing this transition.

cond-mat.quant-gas↗

arXiv2011

A constrained theory of non-BCS type superconductivity in gapped Graphene

We show that gapped Graphene, with a local constraint that current arising from the two valley fermions are exactly equal, shows a non-BCS type superconductivity. Unlike the conventional mechanisms, this superconductivity phenomenon does not require any pairing. We estimate the critical temperature for superconducting-to-normal transition via Berezinskii-Kosterlitz-Thouless mechanism, and find that it is proportional to the gap.

cond-mat.supr-con↗

arXiv2011

Travelling wave solutions to nonlinear Schrodinger equation with self-steepening and self-frequency shift

We investigate exact travelling wave solutions of higher order nonlinear Schrodinger equation in the absence of third order dispersion, which exhibit non-trivial self phase modulation. It is shown that, the corresponding dynamical equation, governing the evolution of intensity in the femtosecond regime, is that of non-linear Schrodinger equation with a source. The exact localized solutions to this system can have both super and subluminal propagation belonging to two distinct class. A number of these solitons exhibit chirality, thereby showing preferential propagation behavior determined by group velocity dispersion. Both localized bright and dark solitons are found in complementary velocity and experimental parameter domains, which can exist for anomalous and normal dispersion regimes. It is found that, dark solitons in this system propagate with non-zero velocity, unlike their counterpart in nanosecond regime. Interestingly, subluminal propagation is observed for solitons having a nontrivial Pade type intensity profile.

nlin.PS↗

arXiv2010

Possible Realization of non-BCS type Superconductivity in Graphene

We show that the gauge field induced due to non-uniform hopping, in gapped graphene, can give rise to a non-BCS type of superconductivity. Unlike the conventional mechanisms, this superconductivity phenomena does not require any pairing. We estimate the critical temperature for superconducting-to-normal transition via Berezinskii-Kosterlitz-Thouless mechanism. Possibility of observing the same in ultra cold atomic gases is also pointed out.

cond-mat.supr-con↗

arXiv2009

Classical solutions for Yang-Mills-Chern-Simons field coupled to an external source

We find wide class of exact solutions of Yang-Mills-Chern-Simons theory coupled to an external source, in terms of doubly periodic Jacobi elliptic functions. The obtained solutions include localized solitons, trigonometric solutions, pure cnoidal waves, and singular solutions in certain parameter range. Furthermore, it is observed that these solutions exist over a nonzero background.

hep-th↗

arXiv2008

Chirped chiral solitons in nonlinear Schrödinger equation with self-steepening and self-frequency shift

We find exact solutions to nonlinear Schrödinger equation in the presence of self-steepening and self-frequency shift. These include periodic solutions and localized solutions of dark-bright type which can be {\emph{chiral}}, and chirality being controlled by sign of self steepening term. A new form of self phase modulation, which can be tuned by higher order nonlinearities as also by the initial conditions, distinct from nonlinear Schrödinger equation, characterizes these solutions. In certain nontrivial parameter domain solutions are found to satisfy {\emph{linear}} Schrödinger equation, indicating possiblity of linear superposition in this nonlinear system. Dark and bright solitons exist in both anomalous and normal dispersion regimes and a duality between dark-bright type of solution and kinematic-higher order chirping is also seen. Localized kink solutions similar to NLSE solitons, but with very different self phase modulation, are identified.

nlin.SI↗