Masaya Kunimi

J-GLOBAL         Last updated: Dec 7, 2019 at 00:24

Research Areas


Published Papers

Ultrafast creation of overlapping Rydberg electrons in an atomic BEC and Mott-insulator lattice
M. Mizoguchi, Y. Zhang, M. Kunimi, A. Tanaka, S. Takeda, N. Takei, V. Bharti, K. Koyasu, T. Kishimoto, D. Jaksch, A. Glaetzle, M. Kiffner, G. Masella, G. Pupillo, M. Weidemüller, and K. Ohmori
An array of ultracold atoms in an optical lattice (Mott insulator) excited to a state where single electron wavefunctions
spatially overlap would represent a new and ideal platform to simulate exotic electronic many-body
phenomena in the condensed...
Masaya Kunimi and Ippei Danshita
Phys. Rev. A 100, 063617 (2019)   100    [Refereed]
We investigate the stability of nonequilibrium steady states of Bose-Einstein condensates with a local one-body loss in the presence of double potential barriers. We construct an exactly solvable mean-field model, in which the local loss and the p...
Kazuma Nagao, Masaya Kunimi, Yosuke Takasu, Yoshiro Takahashi, Ippei Danshita
Phys. Rev. A 99, 023622 (2019)      2019   [Refereed]
We analyze the time evolution of the Bose-Hubbard model after a sudden
quantum quench to a weakly interacting regime. Specifically, motivated by a
recent experiment at Kyoto University, we numerically simulate redistribution
of the kinetic and ons...
Masaya Kunimi, Ippei Danshita
Phys. Rev. A 99, 043613 (2019)      2019   [Refereed]
We study the supercurrent decay of a Bose-Einstein condensate in a ring trap combined with a repulsive barrier potential. In recent experiments, Kumar {\it et al.} [Phys. Rev. A {\bf 95}, 021602(R) (2017)] have measured the dependence of the decay...
Masaya Kunimi, Ippei Danshita
Phys. Rev. A 95, 033637 (2017)      2017   [Refereed]
We study the decay of superflow via thermally activated phase slips in
one-dimensional Bose gases in a shallow optical lattice. By using the Kramers
formula, we numerically calculate the nucleation rate of a thermally activated
phase slip for vari...
Yujiro Eto, Masahiro Takahashi, Masaya Kunimi, Hiroki Saito, Takuya Hirano
New J. Phys. 18, 073029 (2016)      2016   [Refereed]
The non-equilibrium spatial dynamics in a two-component Bose-Einstein
condensate were excited by controlled miscible-immiscible transition, in which
immiscible condensates with domain structures are transferred to the miscible
condensates by chang...
Yujiro Eto, Masahiro Takahashi, Keita Nabeta, Ryotaro Okada, Masaya Kunimi, Hiroki Saito, Takuya Hirano
Phys. Rev. A 93, 033615 (2016)      2016   [Refereed]
We investigate dynamic properties of bouncing and penetration in colliding
binary and ternary Bose-Einstein condensates comprised of different Zeeman or
hyperfine states of 87Rb. Through the application of magnetic field gradient
pulses, two- or t...
Yujiro Eto, Masaya Kunimi, Hidekatsu Tokita, Hiroki Saito, Takuya Hirano
Phys. Rev. A 92, 013611 (2015)      2015   [Refereed]
We investigate flow properties of immiscible Bose-Einstein condensates
composed of two different Zeeman spin states of 87Rb. Spatially overlapping two
condensates in the optical trap are prepared by application of a resonant radio
frequency pulse,...
Masaya Kunimi, Hiroki Saito
Phys. Rev. A 91, 043624 (2015)      2015   [Refereed]
Using a variational method, we derive an exact upper bound for one-magnon
excitation energy in ferromagnetic spinor gases, which limits the quantum
corrections to the effective mass of a magnon to be positive. We also derive an
upper bound for one...
Hiroki Saito, Masaya Kunimi
Phys. Rev. A 91, 041603(R) (2015)      2015   [Refereed]
Motivated by the recent experiment performed by the Berkeley group [G. E.
Marti {\it et al.}, Phys. Rev. Lett. {\bf 113}, 155302 (2014)], we consider the
dynamics of magnons in a spin-1 spinor-dipolar Bose-Einstein condensate, using
mean-field the...
Masaya Kunimi
Phys. Rev. A 90, 063632 (2014)      2014   [Refereed]
We investigate the metastability of a ferromagnetic spin-1 Bose-Einstein
condensate confined in a quasi-one-dimensional rotating ring trap by solving
the spin-1 Gross-Pitaevskii equation. We find analytical solutions that exhibit
spin textures. By...
Masaya Kunimi, Yusuke Kato
Phys. Rev. A 91, 053608 (2015)      2015   [Refereed]
We solve the Gross-Pitaevskii (GP) and Bogoliubov equations to investigate
the metastability of superfluidity in a Bose-Einstein condensate in the
presence of a uniformly moving defect potential in a two-dimensional torus. We
calculate the total e...
Masaya Kunimi, Yusuke Kato
J. Low Temp. Phys. 175, 201 (2014)      2014   [Refereed]
We investigate excitations and fluctuations of Bose-Einstein condensates in a
two-dimensional torus with a uniformly moving Gaussian potential by solving the
Gross-Pitaevskii equation and the Bogoliubov equation. The energy gap Tex
between th...
Masaya Kunimi, Yusuke Kato
Phys. Rev. B 86, 060510(R) (2012)      2012   [Refereed]
The soft-core boson system is one of the simplest models of supersolids,
which have both off-diagonal long-range order (Bose-Einstein condensation) and
diagonal long-range order (crystalline order). Although this model has been
studied from variou...
Masaya Kunimi, Michikazu Kobayashi, Yusuke Kato
J. Phys.: Conf. Ser. 400, 012037 (2012)      2012   [Refereed]
We study dynamical properties of one-dimensional supersolids in the framework of the Gross-Pitaevskii equation with a finite-range two-body interaction in the presence of an obstacle. Above a critical velocity, superfluidity breaks down and solito...
Masaya Kunimi, Yuki Nagai, Yusuke Kato
Phys. Rev. B 84, 094521 (2011)      Sep 2011   [Refereed]
We demonstrate that superflow past an obstacle is possible in a solid phase in the one-dimensional Gross-Pitaevskii equation with a finite-range two-body interaction. The phenomenon we find is analogous to the dc Josephson effect in superconductor...

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