Physics and Astronomy, Condensed Matter Physics, Atomic and Molecular Physics, and Optics
359
Scopus Publications
Scopus Publications
C++ CUDA programs for solving the time-dependent dipolar Gross-Pitaevskii equation Denis Mujo, Dušan Vudragović, Paulsamy Muruganandam, Sadhan K. Adhikari Computer Physics Communications, 2026 This paper introduces an improved version of our previous CUDA programs [1] for solving the dipolar Gross-Pitaevskii equation in three spatial dimensions, now incorporating a quantum fluctuation term [2] , [3] , [4] . This enhancement is vital for accurately modeling quantum dipolar droplets [5] , [6] in dipolar Bose-Einstein condensates. Originally developed in C, the code has been transitioned to C++ to take advantage of its features. Speedup tests were conducted on two types of GPU cards – one commercial and one HPC-optimized – and the results were compared to earlier versions on GPUs and a modern HPC cluster. Both configurations showed an increase in speed.
Quasi-two-dimensional soliton in a self-repulsive spin-orbit-coupled dipolar binary condensate S. K. Adhikari Physical Review E, 2026 We study the formation of solitons in a uniform quasi-two-dimensional (quasi-2D) spin-orbit (SO) coupled self-repulsive binary dipolar and nondipolar Bose-Einstein condensate (BEC) using the mean-field Gross-Pitaevskii equation. For a weak SO coupling, in a nondipolar BEC, one can have three types of degenerate solitons: a multiring soliton with intrinsic vorticity of angular momentum projection +1 or -1 in one component and 0 in the other, a circularly asymmetric soliton, and a stripe soliton with stripes in the density. For an intermediate SO coupling, the multiring soliton ceases to exist and a square-lattice soliton appears with a spatially periodic pattern in density on a square lattice, in addition to the degenerate circularly asymmetric and stripe solitons. In the presence of a dipolar interaction, with the polarization direction aligned in the quasi-2D plane, only the degenerate circularly asymmetric and stripe solitons appear.
Spatially periodic states in a strongly dipolar 164Dy - 162Dy mixture S. K. Adhikari Physical Review A, 2025 We demonstrate the formation of a novel eigenstate in a strongly dipolar binary $^{164}\mathrm{Dy}\text{\ensuremath{-}}^{162}\mathrm{Dy}$ mixture, where the inter- and intraspecies dipolar lengths are larger than the corresponding scattering lengths. When this mixture is confined by a quasi-two-dimensional harmonic trap, the total density exhibits the formation of droplets on a spatially symmetric triangular or square lattice, where each droplet is formed of a single species of atoms; two types of atoms never exist on the same lattice site. The density of any of the species shows a partially filled incomplete lattice; only the total density exhibits a completely full lattice structure. In this theoretical investigation we employ the numerical solution of an improved mean-field model including a Lee-Huang-Yang-type interaction in the intraspecies components alone, meant to stop a collapse of the atoms at high atom density.
Dynamically stable two- and four-droplet solitons in a very strongly dipolar NaCs condensate S. K. Adhikari Physical Review E, 2025 A strongly dipolar Bose-Einstein condensate (BEC) of Dy atoms could sustain different types of states not possible in a nondipolar BECs. Motivated by the observation of a very strongly dipolar condensate of NaCs molecules [N. Bigagli et al., Nature (London) 631, 289 (2024)0028-083610.1038/s41586-024-07492-z], with dipolar interaction stronger by more than an order of magnitude compared with that of Dy atoms, we demonstrate that, in a very strongly dipolar NaCs BEC, it is possible to have a two- and a four-droplet metastable soliton, axially free along the polarization z direction. In this study, we employ imaginary-time propagation of an improved mean-field model, including the Lee-Huang-Yang interaction. The dipolar solitons are subject to an expulsive Gaussian potential at the center and a harmonic potential, both acting in the x-y plane. The phase-coherent solitons, possessing the isolated droplets, are free to move along the z-axis without any relative motion between the droplets. The dynamical stability and mobility of these solitons are demonstrated by real-time propagation employing the converged imaginary-time wave function as the initial state.
Quasi-one- and quasi-two-dimensional symbiotic solitons bound by dipolar interaction S. K. Adhikari Physical Review E, 2024 We study the formation of quasi-one- (quasi-1D) and quasi-two-dimensional (quasi-2D) symbiotic solitons bound by an interspecies dipolar interaction in a binary dipolar Bose-Einstein condensate. These binary solitons have a repulsive intraspecies contact interaction stronger than the intraspecies dipolar interaction, so that they can not be bound in isolation in the absence of an interspecies dipolar interaction. These symbiotic solitons are bound in the presence of an interspecies dipolar interaction and zero interspecies contact interaction. The quasi-1D solitons are free to move along the polarization z direction of the dipolar atoms, whereas the quasi-2D solitons move in the x-z plane. To illustrate these, we consider a ^{164}Er-^{166}Er mixture with scattering lengths a(^{164}Er)=81a_{0} and a(^{166}Er)=68a_{0} and with dipolar lengths a_{dd}(^{164}Er)≈a_{dd}(^{166}Er)≈65a_{0}, where a_{0} is the Bohr radius. In each of the two components a>a_{dd}, which stops the binding of solitons in each component in isolation, whereas a binary quasi-1D or a quasi-2D ^{164}Er-^{166}Er soliton is bound in the presence of an interspecies dipolar interaction. The stationary states were obtained by imaginary-time propagation of the underlying mean-field model; dynamical stability of the solitons was established by real-time propagation over a long period of time.
The BCS-Bose crossover theory S.K. Adhikari, M. de Llano, F.J. Sevilla, M.A. Solís, J.J. Valencia Physica C Superconductivity and Its Applications, 2007
Differential cross sections for elastic and inelastic positronium-hydrogen-atom scattering Physical Review A Atomic Molecular and Optical Physics, 2001
Cooper pair dispersion relation for weak to strong coupling Sadhan K. Adhikari, M. Casas, A. Puente, A. Rigo, M. Fortes, M. A. Solís, M. de Llano, Ariel A. Valladares, O. Rojo Physical Review B Condensed Matter and Materials Physics, 2000
Dynamical calculation of direct muon-transfer rates from thermalized muonic hydrogen to C6+ and O8+ Physical Review A Atomic Molecular and Optical Physics, 2000
Quantum tunneling fragmentation model Borko D. Stošić, M. A. F. Gomes, Sadhan K. Adhikari Physical Review E Statistical Physics Plasmas Fluids and Related Interdisciplinary Topics, 2000
Superconductivity as a Bose-Einstein condensation? S.K. Adhikari, M. Casas, A. Puente, A. Rigo, M. Fortes, M.A. Solís, M. de Llano, A.A. Valladares, O. Rojo Physica C Superconductivity and Its Applications, 2000
Cooper pair dispersion relation in two dimensions S.K. Adhikari, M. Casas, A. Puente, A. Rigo, M. Fortes, M.A. Solís, M. de Llano, A.A. Valladares, O. Rojo Physica C Superconductivity and Its Applications, 2000
