arXiv subjects

C. Nagaraja Kumar

Publications and source records attributed to C. Nagaraja Kumar.

6 recordsLinked to original sources

arXiv2007

Complex solitons with power law behaviour in Bose-Einstein condensates near Feshbach resonance

Complex, localized stable solitons, characterized by a power law behaviour, are found for a quasi-one-dimensional Bose-Einstein condensate near Feshbach resonance. Both dark and bright solitons can be excited in the experimentally allowed parameter domain, when two and three-body interactions are respectively repulsive and attractive. These solutions are obtained for non-zero chemical potential, unlike their unstable real counterparts which exist in the limit of vanishing $μ$. The dark solitons travel with constant speed, which is quite different from the Lieb mode, where profiles with different speeds, bounded above by sound velocity can exist for specified interaction strengths.

cond-mat.other↗

arXiv2003

Quantum information entropies of the eigenstates and the coherent state of the Pöschl-Teller potential

The position and momentum space information entropies, of the ground state of the Pöschl-Teller potential, are exactly evaluated and are found to satisfy the bound, obtained by Beckner, Bialynicki-Birula and Mycielski. These entropies for the first excited state, for different strengths of the potential well, are then numerically obtained. Interesting features of the entropy densities, owing their origin to the excited nature of the wave functions, are graphically demonstrated. We then compute the position space entropies of the coherent state of the Pöschl-Teller potential, which is known to show revival and fractional revival. Time evolution of the coherent state reveals many interesting patterns in the space-time flow of information entropy.

quant-ph↗

arXiv2003

Exact solitary wave solutions of the nonlinear Schrödinger equation with a source

We use a fractional transformation to connect the traveling wave solutions of the nonlinear Schrödinger equation (NLSE), phase-locked with a source, to the elliptic functions satisfying, $f^{\prime\prime}\pm af\pm λf^{3}=0$. The solutions are {\it necessarily} of the rational form, containing both trigonometric and hyperbolic types as special cases. Bright, and dark solitons, respectively, for attractive and repuslive type of nonlinearities, as also singular solitons, are obtained in suitable range of parameter values.

nlin.SI↗

arXiv1999

Compacton-like Solutions for Modified KdV and other Nonlinear Equations

We present compacton-like solution of the modified KdV equation and compare its properties with those of the compactons and solitons. We further show that, the nonlinear Schr{ö}dinger equation with a source term and other higher order KdV-like equations also possess compact solutions of the similar form.

solv-int↗

arXiv1998

Chiral Solitons in a Current Coupled Schrödinger Equation With Self Interaction

Recently non-topological chiral soliton solutions were obtained in a derivatively coupled non-linear Schrödinger model in 1+1 dimensions. We extend the analysis to include a more general self-coupling potential (which includes the previous cases) and find chiral soliton solutions. Interestingly even the magnitude of the velocity is found to be fixed. Energy and U(1) charge associated with this non-topological chiral solitons are also obtained.

cond-mat↗

arXiv1996

New Exactly and Conditionally Exactly Solvable N-Body Problems in One Dimension

We study a class of Calogero-Sutherland type one dimensional N-body quantum mechanical systems, with potentials given by $$ V( x_1, x_2, \cdots x_N) = \sum_{i <j} {g \over {(x_i - x_j)^2}} - \frac{g^{\prime}}{\sum_{i<j}(x_i - x_j)^2} + U(\sqrt{\sum_{i<j}(x_i - x_j)^2}),$$ where $U(\sqrt{\sum_{i<j}(x_i - x_j)^2})$'s are of specific form. It is shown that, only for a few choices of $U$, the eigenvalue problems can be solved {\it exactly}, for arbitrary $g^{\prime}$. The eigen spectra of these Hamiltonians, when $g^{\prime} \ne 0$, are non-degenerate and the scattering phase shifts are found to be energy dependent. It is further pointed out that, the eigenvalue problems are amenable to solution for wider choices of $U$, if $g^{\prime}$ is conveniently fixed. These conditionally exactly solvable problems also do not exhibit energy degeneracy and the scattering phase shifts can be computed {\it only} for a specific partial wave.

hep-th↗