Critical velocity of superfluid flow through single barrier and periodic potentials (2009)
Watanabe, Gentaro, Dalfovo, F., Piazza, F., Pitaevskii, L. P., Stringari, S.
We investigate the problem of an ultracold atomic gas in the superfluid phase flowing in the presence of a potential barrier or a periodic potential. We use a hydrodynamic scheme in the local density...
Formation of Nuclear "Pasta" in Supernovae (2009)
Watanabe, Gentaro, Sonoda, Hidetaka, Maruyama, Toshiki, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
In supernova cores, nuclear "pasta" phases such as triangular lattice of rod-like nuclei and layered structure of slab-like nuclei are considered to exist. However, it is still unclear whether or not...
Efficient scheme for breeding beautiful Schr\"odinger cat in a double-well potential (2009)
For trapped cold Bose gases in a double-well potential, we propose a new scheme for creating the Schr\"odinger cat state in which all particles in the right or left wells (so called NOON state). This...
Equation of state and effective mass of the unitary Fermi gas in a 1D periodic potential (2008)
Watanabe, Gentaro, Orso, Giuliano, Dalfovo, Franco, Pitaevskii, Lev P., Stringari, Sandro
By solving the Bogoliubov -- de Gennes equations at zero temperature, we study the effects of a one-dimensional optical lattice on the behavior of a superfluid Fermi gas at unitarity. We show that,...
Phase diagram of nuclear ``pasta' and its uncertainties in supernova cores (2007)
Sonoda, Hidetaka, Watanabe, Gentaro, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
We examine the model dependence of the phase diagram of inhomogeneous nulcear matter in supernova cores using the quantum molecular dynamics (QMD). Inhomogeneous matter includes crystallized matter...
Tkachenko modes in a superfluid Fermi gas at unitarity (2007)
Watanabe, Gentaro, Cozzini, Marco, Stringari, Sandro
We calculate the frequencies of the Tkachenko oscillations of a vortex lattice in a harmonically trapped superfluid Fermi gas. We use the elasto-hydrodynamic theory by properly accounting for the...
Impact of nuclear "pasta" on neutrino transport in collapsing stellar cores (2007)
Sonoda, Hidetaka, Watanabe, Gentaro, Sato, Katsuhiko, Takiwaki, Tomoya, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Nuclear ``pasta'', nonspherical nuclei in dense matter, is predicted to occur in collapsing supernova cores. We show how pasta phases affect the neutrino transport cross section via weak neutral...
Reversal of the circulation of a vortex by quantum tunneling in trapped Bose systems (2007)
Watanabe, Gentaro, Pethick, C. J.
We study the quantum dynamics of a model for a vortex in a Bose gas with repulsive interactions in an anisotropic, harmonic trap. By solving the Schr\"odinger equation numerically, we show that the...
Understanding nuclear "pasta": current status and future prospects (2006)
In cores of supernovae and crusts of neutron stars, nuclei can adopt interesting shapes, such as rods or slabs, etc., which are referred to as nuclear "pasta." In recent years, we have studied the...
Non-uniform vortex lattices in inhomogeneous rotating Bose-Einstein condensates (2006)
Baym, Gordon, Pethick, C. J., Gifford, S. Andrew, Watanabe, Gentaro
We derive a general framework, in terms of elastic theory, for describing the distortion of the vortex lattice in a rotating Bose-Einstein condensate at arbitrary rotation speed and determining the...
Structure of vortices in rotating Bose-Einstein condensates (2006)
Watanabe, Gentaro, Gifford, S. Andrew, Baym, Gordon, Pethick, C. J.
We calculate the structure of individual vortices in rotating Bose-Einstein condensates in a transverse harmonic trap. Making a Wigner-Seitz approximation for the unit cell of the vortex lattice, we...
BCS-BEC Crossover in Atomic Fermi Gases with a Narrow Resonance (2006)
Jensen, L. M., Nilsen, H. M., Watanabe, Gentaro
We determine the effects on the BCS-BEC crossover of the energy dependence of the effective two-body interaction, which at low energies is determined by the effective range. To describe interactions...
Experiments on the axial breathing mode in a rapidly rotating Bose-Einstein condensate are examined. Assuming a cold cloud without thermal component, we show that errors due to defocus of an imaging...
Recent progress on understanding "pasta" phases in dense stars (2005)
Watanabe, Gentaro, Sonoda, Hidetaka
In cores of supernovae and crusts of neutron stars, nuclei can adopt interesting shapes, such as rods or slabs, etc., which are referred to as nuclear "pasta." Recently, we have been studying the...
Breathing mode of rapidly rotating Bose-Einstein condensates (2005)
We show that the breathing mode of a rapidly-rotating, harmonically-trapped Bose-Einstein condensate may be described by a generalized lowest Landau level (LLL) wave function, in which the oscillator...
Dynamical Simulation of Nuclear "Pasta": Soft Condensed Matter in Dense Stars (2005)
Watanabe, Gentaro, Sonoda, Hidetaka
More than twenty years ago, it was predicted that nuclei can adopt interesting shapes, such as rods or slabs, etc., in the cores of supernovae and the crusts of neutron stars. These non-spherical...
Simulation of Transitions between "Pasta" Phases in Dense Matter (2004)
Watanabe, Gentaro, Maruyama, Toshiki, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Calculations of equilibrium properties of dense matter predict that at subnuclear densities nuclei can be rodlike or slablike. To investigate whether transitions between phases with non-spherical...
Landau levels and the Thomas-Fermi structure of rapidly rotating Bose-Einstein condensates (2004)
Watanabe, Gentaro, Baym, Gordon, Pethick, C. J.
We show that, within mean-field theory, the density profile of a rapidly rotating harmonically trapped Bose-Einstein condensate is of the Thomas-Fermi form as long as the number of vortices is much...
Watanabe, Gentaro, Pethick, C. J.
We study the global density profile of a rapidly rotating Bose-Einstein condensate in a harmonic trap with transverse frequency $\omega_{\perp}$. By introducing an additional variational degree of...
Phases of hot nuclear matter at subnuclear densities (2003)
Watanabe, Gentaro, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Structure of hot dense matter at subnuclear densities is investigated by quantum molecular dynamics (QMD) simulations. We analyze nucleon distributions and nuclear shapes using two-point correlation...
Nuclear pasta structure in hot neutron stars (2003)
Watanabe, Gentaro, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Structure of cold and hot dense matter at subnuclear densities is investigated by quantum molecular dynamics (QMD) simulations. Obtained phase diagrams show that the density of the phase boundaries...
Electron screening in the liquid-gas mixed phases of nuclear matter (2003)
Screening effects of electrons on inhomogeneous nuclear matter, which includes spherical, slablike, and rodlike nuclei as well as spherical and rodlike nuclear bubbles, are investigated in view of...
Structure of cold nuclear matter at subnuclear densities by Quantum Molecular Dynamics (2003)
Watanabe, Gentaro, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Structure of cold nuclear matter at subnuclear densities for the proton fraction $x=0.5$, 0.3 and 0.1 is investigated by quantum molecular dynamics (QMD) simulations. We demonstrate that the phases...
Microscopic Study of Slablike and Rodlike Nuclei: Quantum Molecular Dynamics Approach (2002)
Watanabe, Gentaro, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Structure of cold dense matter at subnuclear densities is investigated by quantum molecular dynamics (QMD) simulations. We succeeded in showing that the phases with slab-like and rod-like nuclei etc....
Microscopic Study of Nuclear "Pasta" by Quantum Molecular Dynamics (2001)
Watanabe, Gentaro, Sato, Katsuhiko, Yasuoka, Kenji, Ebisuzaki, Toshikazu
Structure of cold dense stellar matter at subnuclear densities is investigated with quantum molecular dynamics (QMD). We succeeded in showing that the phases with slab-like and rod-like nuclei etc....
Formation of Nuclear "Pasta" in Cold Neutron Star Matter (2001)
Iida, Kei, Watanabe, Gentaro, Sato, Katsuhiko
Formation and decay of rod-like and slab-like nuclei, as may be encountered in the outer parts of neutron stars, are examined within a zero-temperature stability analysis with respect to...
Effects of Neutrino Trapping on Thermodynamic Properties of Nuclear ``Pasta'' (2000)
Watanabe, Gentaro, Iida, Kei, Sato, Katsuhiko
Geometrical structure of matter at subnuclear densities is investigated in the presence of a degenerate gas of neutrinos as encountered in stellar collapse. The crystalline phases with spherical,...
Thermodynamic properties of nuclear "pasta" in neutron star crusts (2000)
Watanabe, Gentaro, Iida, Kei, Sato, Katsuhiko
Equilibrium phase diagrams for neutron star matter at subnuclear densities are obtained at zero temperature. Spherical, rod-like and slab-like nuclei as well as spherical and rod-like nuclear bubbles...