59 citations · 93 across the 17 of their papers we have counts for
17 papers
Efficiency of Continuous-Time Quantum Monte Carlo Updates in the Ferromagnetic State of the Doped SU(3) Fermi-Hubbard Model
Juntaro Fujii, Kazuki Yamamoto, Akihisa Koga
We investigate the sampling efficiency in a segment-based continuous-time hybridization-expansion quantum Monte Carlo solver within dynamical mean-field theory for the doped SU(3)…
Stealthy hyperuniform disorder: A new route to controlling electric states and magnetic phase transition in correlated systems
Akihisa Koga, Takanori Sugimoto
We investigate the effects of stealthy hyperuniform bond distributions on the electronic and magnetic properties of the Hubbard model on the honeycomb lattice. Hyperuniform structu…
Impact of Stealthy Hyperuniform Magnetic Impurity Configurations on Bulk Magnetism in a Two-dimensional Heisenberg Model
K. Asakura, K. Yamamoto, A. Koga
We investigate an antiferromagnetic quantum Heisenberg model on a square lattice with high-spin magnetic impurities to clarify how random and stealthy hyperuniform impurity configu…
Generalized Nagaoka ferromagnetism accompanied by flavor-selective Mott states in an SU() Fermi-Hubbard model
Juntaro Fujii, Kazuki Yamamoto, Akihisa Koga
We study the ferromagnetic instability in an SU() Fermi-Hubbard model on the hypercubic lattice. Combining dynamical mean-field theory with continuous-time quantum Monte Carlo s…
Elliptical-rod geometries enhance photonic band gaps in disordered stealthy hyperuniform photonic crystals
Kota Asakura, Kazuki Yamamoto, Akihisa Koga
We study two-dimensional photonic crystals composed of elliptical dielectric rods arranged according to stealthy hyperuniform point patterns. These patterns are characterized by th…
Dimensionality effect on exceptional fermionic superfluidity with spin-dependent asymmetric hopping
Soma Takemori, Kazuki Yamamoto, Akihisa Koga
Non-Hermitian (NH) quantum systems host exceptional points (EPs), where eigenstates and eigenvalues coalesce, leading to unconventional many-body phenomena absent in Hermitian syst…
Holographic Aspects of Dynamical Mean-Field Theory
Kouichi Okunishi, Akihisa Koga
Dynamical mean-field theory (DMFT) is one of the most standard theoretical frameworks for addressing strongly correlated electron systems. In this study, we explore a holographic r…
Itinerant ferromagnetism in an SU(3) Fermi-Hubbard model at finite temperatures: A dynamical mean-field theory study
Juntaro Fujii, Kazuki Yamamoto, Akihisa Koga
We investigate an SU(3) Fermi-Hubbard model on a hypercubic lattice at finite temperatures, combining dynamical mean-field theory with continuous-time quantum Monte Carlo simulatio…
Modulated honeycomb lattices and their magnetic properties
Akihisa Koga, Toranosuke Matsubara
We propose a family of modulated honeycomb lattices, a class of quasiperiodic tilings characterized by the metallic mean. These lattices consist of six distinct hexagonal prototile…
Spin-Depairing-Induced Exceptional Fermionic Superfluidity
Soma Takemori, Kazuki Yamamoto, Akihisa Koga
We investigate the non-Hermitian (NH) attractive Hubbard model with spin depairing, which is a spin-resolved asymmetric hopping that nonreciprocally operates spins in the opposite…
Measurement-induced phase transitions for free fermions in a quasiperiodic potential
Toranosuke Matsubara, Kazuki Yamamoto, Akihisa Koga
We study the dynamics under continuous measurements for free fermions in a quasiperiodic potential by using the Aubry-André-Harper model with hopping rate and potential strengt…
Triangular and dice quasicrystals modulated by generic 1D aperiodic sequences
Toranosuke Matsubara, Akihisa Koga, Tomonari Dotera
We present a method for generating hexagonal aperiodic tilings that are topologically equivalent to the triangular and dice lattices. This approach incorporates aperiodic sequences…
Critical behavior of the Ising model on square-triangle tilings
Akihisa Koga, Shiro Sakai
We investigate magnetic properties of the ferromagnetic Ising model on square-triangle tilings to explore how the hyperuniformity, which characterizes long-range behavior of the po…
Hyperuniform properties of the square-triangle tilings
Akihisa Koga, Shiro Sakai, Yushu Matsushita +1
We study hyperuniform properties for the square-triangle tilings. The tiling is generated by a local growth rule, where squares or triangles are iteratively attached to its boundar…
Phase diagram of non-Hermitian BCS superfluids in a dissipative asymmetric Hubbard model
Soma Takemori, Kazuki Yamamoto, Akihisa Koga
We investigate the non-Hermitian (NH) attractive Fermi-Hubbard model with asymmetric hopping and complex-valued interactions, which can be realized by collective one-body loss and…
Aperiodic approximants bridging quasicrystals and modulated structures
Toranosuke Matsubara, Akihisa Koga, Atsushi Takano +2
Aperiodic crystals constitute a fascinating class of materials that includes incommensurate (IC) modulated structures and quasicrystals (QCs). Although these two categories share a…
Incipient and well-developed entropy plateaus in spin-S Kitaev models
J. Oitmaa, A. Koga, R. R. P. Singh
We present results on entropy and heat-capacity of the spin-S honeycomb-lattice Kitaev models using high-temperature series expansions and thermal pure quantum (TPQ) state methods.…