38 citations · 39 across the 2 of their papers we have counts for
5 papers
Quantum Phase Transitions in the Hubbard Model on Triangular Lattice
Takuya Yoshioka, Akihisa Koga, Norio Kawakami
We investigate the quantum phase transitions in the half-filled Hubbard model on the triangular lattice by means of the path-integral renormalization group (PIRG) method with a new…
Supersolid state of ultracold fermions in an optical lattice
Akihisa Koga, Takuji Higashiyama, Kensuke Inaba +2
We study ultracold fermionic atoms trapped in an optical lattice with harmonic confinement by means of the dynamical mean-field approximation. It is demonstrated that a supersolid…
Variational Monte Carlo analysis of the Hubbard model with a confining potential: one-dimensional fermionic optical lattice systems
Yusuke Fujihara, Akihisa Koga, Norio Kawakami
We investigate the one-dimensional Hubbard model with a confining potential, which may describe cold fermionic atoms trapped in an optical lattice. Combining the variational Monte…
Excitation Spectrum for Quantum Spin Systems with Ladder, Plaquette and Mixed-Spin Structures
Akihisa Koga, Norio Kawakami
By using the series expansion techniques, we study the excitation spectrum for the two-dimensional quantum spin systems with ladder, plaquette and mixed-spin structures. We calcula…
Mixed-spin cluster expansion for a quasi-one-dimensional Haldane system
Akihisa Koga, Norio Kawakami
We present a novel mixed-spin cluster expansion method for a quasi-one-dimensional Haldane system with bond alternation. By mapping the s=1 antiferromagnetic spin model on square a…