1.5k citations · 2.2k across the 36 of their papers we have counts for
36 papers
Entanglement Generation Beyond Quantum Theory: From Product States to Popescu-Rohrlich Boxes
Shun Umekawa, Akihiro Hokkyo, Hayato Arai +1
Entanglement generation is a fundamental dynamical capability in quantum information science and underpins many quantum advantages. While quantum theory enables it through unitary…
Generating collective spin cat states via photon-number measurements near the Dicke critical point
Taiga Nakamoto, Shohei Imai, Kazuaki Takasan
We propose a method for generating collective spin cat states in a cavity-coupled atomic ensemble by exploiting strong light-matter entanglement and anti-squeezing associated with…
One-dimensional extended Hubbard model coupled with an optical cavity
Taiga Nakamoto, Kazuaki Takasan, Naoto Tsuji
We study the one-dimensional extended Hubbard model coupled with an optical cavity, which describes an interplay of the effect of vacuum fluctuation of light and the quantum phase…
Current-Enabled Optical Conductivity of Collective Modes in Unconventional Superconductors
Gerrit Niederhoff, Ryusei Kataoka, Kazuaki Takasan +1
We theoretically investigate the current-enabled linear optical conductivity of collective modes in superconductors with unconventional pairing symmetries. After deriving general f…
Superconducting nonlinear Hall effect induced by geometric phases
Kazuaki Takasan, Naoto Tsuji
We study the nonlinear Hall effect in superconductors without magnetic fields induced by a quantum geometric phase (i.e., the Aharonov-Bohm phase) carried by single or pair particl…
Nonequilibrium hysteretic phase transitions in periodically light-driven superconductors
Huanyu Zhang, Kazuaki Takasan, Naoto Tsuji
We find nonequilibrium phase transitions accompanied by multiple (nested) hysteresis behaviors in superconductors coupled to baths under a time-periodic light driving. The transiti…
Partial yet definite emergence of the Kardar-Parisi-Zhang class in isotropic spin chains
Kazumasa A. Takeuchi, Kazuaki Takasan, Ofer Busani +3
Integrable spin chains with a continuous non-Abelian symmetry, such as the one-dimensional isotropic Heisenberg model, show superdiffusive transport with little theoretical underst…
Light-driven interlayer propagation of collective-mode excitations in layered superconductors
Niklas Ziereis, Kazuaki Takasan, Naoto Tsuji
Superconductors exhibit a nonlinear interaction with an applied light, which can resonantly excite the collective amplitude (Higgs) mode. Here we study light-induced dynamics of la…
Activity-induced ferromagnetism in one-dimensional quantum many-body systems
Kazuaki Takasan, Kyosuke Adachi, Kyogo Kawaguchi
We study a non-Hermitian quantum many-body model in one dimension analogous to the Vicsek model or active spin models, and investigate its quantum phase transitions. The model cons…
Light-field-driven non-Ohmic current and Keldysh crossover in a Weyl semimetal
R. Ikeda, H. Watanabe, J. H. Moon +3
In recent years, coherent electrons driven by light fields have attracted significant interest in exploring novel material phases and functionalities. However, observing coherent l…
Patchwork Conditions for Holographic Nonlinear Responses: A Computational Method for Electric Conductivity and Friction Coefficient
Shuta Ishigaki, Shin Nakamura, Kazuaki Takasan
We propose a new method to compute nonlinear transport coefficients in holography, such as nonlinear DC conductivity and nonlinear friction coefficient. The conventional method can…
Drude weights in one-dimensional systems with a single defect
Kazuaki Takasan, Masaki Oshikawa, Haruki Watanabe
Ballistic transport of a quantum system can be characterized by Drude weight, which quantifies the response of the system to a uniform electric field in the infinitely long timesca…
Supercurrent-Induced Weyl Superconductivity
Shuntaro Sumita, Kazuaki Takasan
We show that Weyl superconductivity can be induced by finite supercurrent in noncentrosymmetric spin-orbit-coupled superconductors with line nodes. We introduce a three-dimensional…
Topological d-wave superconductivity in two dimensions
Youichi Yanase, Akito Daido, Kazuaki Takasan +1
Despite intensive searches for topological superconductors, the realization of topological superconductivity remains under debate. Previous proposals for the topological -wave,…
Ferromagnetism in tilted fermionic Mott insulators
Kazuaki Takasan, Masaki Tezuka
We investigate the magnetism in tilted fermionic Mott insulators. With a small tilt, the fermions are still localized and form a Mott-insulating state, where the localized spins in…
Supercurrent-induced topological phase transitions
Kazuaki Takasan, Shuntaro Sumita, Youichi Yanase
We show that finite current in superconductors can induce topological phase transitions, as a result of the deformation of the quasiparticle spectrum by a finite center-of-mass (CO…
Adiabatic transport in one-dimensional systems with a single defect
Kazuaki Takasan, Masaki Oshikawa, Haruki Watanabe
The adiabatic transport properties of U(1) invariant systems are determined by the dependence of the ground state energy on the twisted boundary condition. We examine a one-dimensi…
Exact results for nonlinear Drude weights in the spin-1/2 XXZ chain
Yuhi Tanikawa, Kazuaki Takasan, Hosho Katsura
Nonlinear Drude weight (NLDW) is a new concept which characterizes the nonlinear transport in quantum many-body systems. We investigate these weights for the spin-1/2 XXZ chain in…
Control of superexchange interactions with DC electric fields
Shunsuke C. Furuya, Kazuaki Takasan, Masahiro Sato
We discuss DC electric-field controls of superexchange interactions. We first present generic results about antiferromagnetic and ferromagnetic superexchange interactions valid in…
Breakdown of Markovianity by interactions in stroboscopic Floquet-Lindblad dynamics under high-frequency drive
Kaoru Mizuta, Kazuaki Takasan, Norio Kawakami
Floquet-Magnus (FM) expansion theory is a powerful tool in periodically driven (Floquet) systems under high-frequency drives. In closed systems, it dictates that their stroboscopic…
Activity-induced phase transition in a quantum many-body system
Kyosuke Adachi, Kazuaki Takasan, Kyogo Kawaguchi
A crowd of nonequilibrium entities can show phase transition behaviors that are prohibited in conventional equilibrium setups. An interesting question is whether similar activity-d…
Laser-induced topological -wave superconductivity in bilayer transition metal dichalcogenides
Hiroomi Chono, Kazuaki Takasan, Youichi Yanase
In this paper, we propose a way to realize topological -wave superconductivity with application of circularly polarized laser light in two-dimensional bilayer transition metal d…
Current-induced second harmonic generation in inversion-symmetric Dirac and Weyl semimetals
Kazuaki Takasan, Takahiro Morimoto, Joseph Orenstein +1
Second harmonic generation (SHG) is a fundamental nonlinear optical phenomenon widely used both for experimental probes of materials and for application to optical devices. Even-or…
Anomalous Hydrodynamic Transport in Interacting Noncentrosymmetric Metals
Riki Toshio, Kazuaki Takasan, Norio Kawakami
In highly conductive metals with sufficiently strong momentum-conserving scattering, the electron momentum is regarded as a long-lived quantity, whose dynamics is described by an e…