555 citations · 1.4k across the 22 of their papers we have counts for
22 papers
Observation of non-Hermitian point gap in photonic crystals
Yuto Moritake, Nozomi Ogawa, Issei Takeda +7
Non-Hermitian point gap (NHPG) is a unique phenomenon in non-Hermitian systems and induces non-Hermitian skin effect (NHSE). In photonic crystals, NHPG and the NHSE have previously…
Higher-order exceptional points unveiled by nilpotence and mathematical induction
Kenta Takata, Adam Mock, Masaya Notomi +1
Non-Hermitian systems can have peculiar degeneracies of eigenstates called exceptional points (EPs). An EP of degenerate states is said to have order , and higher-order EPs…
BIC slow light waveguides based on interband coupling
Sae R. Endo, Yuta Tanimura, Takahiro Ito +5
Harnessing bound states in the continuum (BICs) for guiding light in leaky environments has unlocked new possibilities in photonic integrated circuits. BIC confinement enables low-…
Transition from exceptional points to observable nonlinear bifurcation points in anti-PT symmetric coupled cavity systems
Takahiro Uemura, Kenta Takata, Masaya Notomi
Exceptional points (EPs) in anti-parity-time (APT)-symmetric systems have attracted significant interest. While linear APT-symmetric systems exhibit structural similarities with no…
Propagation and circulating modes of reciprocal non-Hermitian skin effect
Issei Takeda, Taiki Yoda, Yuto Moritake +2
The non-Hermitian skin effect (NHSE) is a novel localization phenomenon, in which all bulk states in a non-Hermitian system under certain conditions are localized at the edge of th…
Slow Light Waveguides based on Bound States in the Continuum
Yuta Tanimura, Yuki Ishii, Kenta Takata +4
The concept of bound states in the continuum (BIC) has been advancing light confinement technology in leaky environments. In this letter, we propose and numerically demonstrate a s…
EP restoration and fast-light edge states in photonic crystal waveguide with glide and time reversal symmetry
Takahiro Uemura, Taiki Yoda, Yuto Moritake +3
Exceptional points (EPs) in the propagation states give rise to the emergence of intriguing properties with the divergence of the group velocity. However, there have been no experi…
Optical non-Hermitian skin effect in two-dimensional uniform media
Taiki Yoda, Yuto Moritake, Kenta Takata +3
The non-Hermitian skin effect (NHSE) is a novel localization phenomenon in certain non-Hermitian systems with gain and/or loss. Most of previous works study the non-Hermitian skin…
Improved design and experimental demonstration of ultrahigh-Q C-symmetric H1 hexapole photonic crystal nanocavities
Kenta Takata, Eiichi Kuramochi, Akihiko Shinya +1
An H1 photonic crystal nanocavity is based on a single point defect and has eigenmodes with a variety of symmetric features. Thus, it is a promising building block for photonic tig…
Imaginary couplings in non-Hermitian coupled-mode theory: Effects on exceptional points of optical resonators
Kenta Takata, Nathan Roberts, Akihiko Shinya +1
Exceptional point (EP) degeneracies in coupled cavities with gain and loss provide on-chip photonic devices with unconventional features and performance. However, such systems with…
Emulating the local Kuramoto model with an injection-locked photonic crystal laser array
Naotomo Takemura, Kenta Takata, Masato Takiguchi +1
The Kuramoto model is a mathematical model for describing the collective synchronization phenomena of coupled oscillators. We theoretically demonstrate that an array of coupled pho…
Observing exceptional point degeneracy of radiation with electrically pumped photonic crystal coupled-nanocavity lasers
Kenta Takata, Kengo Nozaki, Eiichi Kuramochi +6
Controlling gain and loss of coupled optical cavities can induce non-Hermitian degeneracies of eigenstates, called exceptional points (EPs). Various unconventional phenomena around…
Active topological photonics
Yasutomo Ota, Kenta Takata, Tomoki Ozawa +6
Topological photonics has emerged as a novel route to engineer the flow of light. Topologically-protected photonic edge modes, which are supported at the perimeters of topologicall…
Photonic Topological Insulating Phase Induced Solely by Gain and Loss
Kenta Takata, Masaya Notomi
We reveal a one-dimensional topological insulating phase induced solely by gain and loss control in non-Hermitian optical lattices. The system comprises units of four uniformly cou…
A 16-bit Coherent Ising Machine for One-Dimensional Ring and Cubic Graph Problems
Kenta Takata, Alireza Marandi, Ryan Hamerly +6
Many tasks in our modern life, such as planning an efficient travel, image processing and optimizing integrated circuit design, are modeled as complex combinatorial optimization pr…
Quantum correlation in degenerate optical parametric oscillators with mutual injections
Kenta Takata, Alireza Marandi, Yoshihisa Yamamoto
We theoretically and numerically study the quantum dynamics of two degenerate optical parametric oscillators with mutual injections. The cavity mode in the optical coupling path be…
Binary phase oscillation of two mutually coupled semiconductor lasers
Shoko Utsunomiya, Naoto Namekata, Kenta Takata +3
A two-site Ising model is implemented as an injection-locked laser network consisting of a single master laser and two mutually coupled slave lasers. We observed ferromagnetic and…
Network of Time-Multiplexed Optical Parametric Oscillators as a Coherent Ising Machine
Alireza Marandi, Zhe Wang, Kenta Takata +2
Finding the ground states of the Ising Hamiltonian [1] maps to various combinatorial optimization problems in biology, medicine, wireless communications, artificial intelligence, a…
Data Search by a Laser Ising Machine with Gradual Pumping or Coupling
Kenta Takata, Yoshihisa Yamamoto
We study two operational schemes for a coherent Ising machine based on an injection-locked laser network. These schemes gradually increase the pumping rate or the mutual coupling a…
Valence-band structure of ferromagnetic semiconductor (InGaMn)As
Shinobu Ohya, Iriya Muneta, Yufei Xin +2
To clarify the whole picture of the valence-band structures of prototype ferromagnetic semiconductors (III,Mn)As (III: In and Ga), we perform systematic experiments of the resonant…
Comment on "Reconciling results of tunnelling experiments on (Ga,Mn)As" arXiv:1102.3267v2 by Dietl and Sztenkiel
Shinobu Ohya, Kenta Takata, Iriya Muneta +2
We comment on the recent paper "Reconciling results of tunnelling experiments on (Ga,Mn)As" arXiv:1102.3267v2 by Dietl and Sztenkiel. They claimed that the oscillations observed in…
Universal valence-band picture of the ferromagnetic semiconductor GaMnAs
Shinobu Ohya, Kenta Takata, Masaaki Tanaka
The origin of ferromagnetism in the prototype ferromagnetic semiconductor GaMnAs is still controversial due to the insufficient understanding of its band structure and Fermi level…