42 citations · 202 across the 23 of their papers we have counts for
24 papers
Phase-shift instanton approach to tunneling duality in Read--Rezayi state
Ryoi Ohashi, Hiroki Isobe, Ryota Nakai +1
We study the duality between quasi-particle and electron tunneling in point-contact geometries of fractional quantum Hall states. To treat non-Abelian edge operators, we introduce…
Topological superconductivity on a kagome magnet coupled to a Rashba superconductor
Koji Kudo, Ryota Nakai, Hiroki Isobe +1
A quantum anomalous Hall system is predicted to realize topological superconductivity when proximity-coupled to an -wave superconductor. A kagome magnet with chiral magnetic ord…
Repulsive-Interaction-Driven Topological Superconductivity in a Landau Level Coupled to an -Wave Superconductor
Koji Kudo, Ryota Nakai, Hiroki Isobe +2
A two-dimensional topologically nontrivial state of noninteracting electrons, such as the surface state of a three-dimensional topological insulator, is predicted to realize a topo…
Chirality-selective proximity effect between chiral -wave superconductors and quantum Hall insulators
Ryota Nakai, Koji Kudo, Hiroki Isobe +1
Heterostructures of superconductors and quantum-Hall insulators are promising platforms of topological quantum computation. However, these two systems are incompatible in some aspe…
Discrete time crystals detected by time-translation twist
Ryota Nakai, Taozhi Guo, Shinsei Ryu
We introduce a boundary condition twisted by time translation as a novel probe to characterize dynamical phases in periodically driven (Floquet) quantum systems. Inspired by twiste…
Quantum anomalous, spin, and valley Hall effects in pentalayer rhombohedral graphene moiré superlattices
Koji Kudo, Ryota Nakai, Kentaro Nomura
Recent experiments on pentalayer rhombohedral graphene moiré superlattices have observed the quantum anomalous Hall effect at moiré filling factor of and various fractional…
Disorder-induced topological superconductivity in a spherical quantum-Hall--superconductor hybrid
Koji Kudo, Ryota Nakai, Kentaro Nomura
Quantum-Hall--Superconductor hybrids have been predicted to exhibit various types of topological order, providing possible platforms for intrinsically fault-tolerant quantum comput…
Twisted-Boundary-Condition Formalism for Thermal Transport and an Application to the One-Dimensional XY Spin Chain
Ryota Nakai, Taozhi Guo, Shinsei Ryu
We introduce and formulate the boundary condition twisted by the energy (time translation) in one-dimensional quantum many-body systems. The stiffness against this boundary conditi…
Higher-order topological superconductor phases in a multilayer system
Ryota Nakai, Kentaro Nomura
Higher-order topological phases are gapped phases of matter that host gapless corner or hinge modes. For the case of superconductors, corner or hinge modes are gapless Majorana mod…
Non-Hermitian boost deformation
Taozhi Guo, Kohei Kawabata, Ryota Nakai +1
The Hatano-Nelson model is one of the most prototypical non-Hermitian models that exhibit the intrinsic non-Hermitian topological phases and the concomitant skin effect. These phen…
Andreev-like Reflection in the Pfaffian Fractional Quantum Hall Effect
Ryoi Ohashi, Ryota Nakai, Takehito Yokoyama +2
We studied the tunnel transport between the edge of a Pfaffian fractional quantum Hall state and that of an integer quantum Hall state. Based on the duality argument between the st…
Energy-twisted boundary condition and response in one-dimensional quantum many-body systems
Ryota Nakai, Taozhi Guo, Shinsei Ryu
Thermal transport in condensed matter systems is traditionally formulated as a response to a background gravitational field. In this work, we seek a twisted-boundary-condition form…
Edge-induced pairing states in a Josephson junction through a spin-polarized quantum anomalous Hall insulator
Ryota Nakai, Kentaro Nomura, Yukio Tanaka
Despite the robustness of the chiral edge modes of quantum Hall systems against the superconducting proximity effect, Cooper pairs can penetrate into the chiral edge channels and c…
Weyl superconductor phases in a Weyl-semimetal/superconductor multilayer
Ryota Nakai, Kentaro Nomura
Topologically nontrivial superconducting phases have been engineered in topological materials by the proximity effect in contact with conventional superconductors. In this paper, b…
Real-time evolution and quantized charge pumping in magnetic Weyl semimetals
Takahiro Misawa, Ryota Nakai, Kentaro Nomura
Real-time evolution and charge pumping in magnetic Weyl semimetals are studied by solving the time-dependent Schrödinger equations. In the adiabatic limit of the real-time evolutio…
Nonreciprocal thermal and thermoelectric transport of electrons in noncentrosymmetric crystals
Ryota Nakai, Naoto Nagaosa
Nonreciprocal transport phenomena indicate that the forward and backward flows differ, and are attributed to broken inversion symmetry. In this paper, we study the nonreciprocity o…
Laughlin's argument for the quantized thermal Hall effect
Ryota Nakai, Shinsei Ryu, Kentaro Nomura
We extend Laughlin's magnetic-flux-threading argument to the quantized thermal Hall effect. A proper analogue of Laughlin's adiabatic magnetic-flux threading process for the case o…
Crossed responses of spin and orbital magnetism in topological insulators
Ryota Nakai, Kentaro Nomura
Crossed magnetic responses between spin and orbital angular momentum are studied in time-reversal symmetric topological insulators. Due to spin-orbit coupling in the quantum spin H…
Finite-temperature effective boundary theory of the quantized thermal Hall effect
Ryota Nakai, Shinsei Ryu, Kentaro Nomura
A finite-temperature effective free energy of the boundary of a quantized thermal Hall system is derived microscopically from the bulk two-dimensional Dirac fermion coupled with a…
Disorder effects on thermal transport on the surface of topological superconductors by the self-consistent Born approximation
Ryota Nakai, Kentaro Nomura
We have studied the longitudinal thermal conductivity of the surface of a three-dimensional time-reversal symmetric topological superconductor with random disorder. Majorana fermio…
Time-reversal symmetric Kitaev model and topological superconductor in two dimensions
Ryota Nakai, Shinsei Ryu, Akira Furusaki
A time-reversal invariant Kitaev-type model is introduced in which spins (Dirac matrices) on the square lattice interact via anisotropic nearest-neighbor and next-nearest-neighbor…
Disordered topological quantum critical points in three-dimensional systems
Ryuichi Shindou, Ryota Nakai, Shuichi Murakami
Generic non-magnetic disorder effects onto those topological quantum critical points (TQCP), which intervene the three-dimensional topological insulator and an ordinary insulator,…
Particle Propagator of Spin Calogero-Sutherland Model
Ryota Nakai, Yusuke Kato
Explicit-exact expressions for the particle propagator of the spin 1/2 Calogero-Sutherland model are derived for the system of a finite number of particles and for that in the ther…
Derivation of Green's Function of Spin Calogero-Sutherland Model by Uglov's Method
Ryota Nakai, Yusuke Kato
Hole propagator of spin 1/2 Calogero-Sutherland model is derived using Uglov's method, which maps the exact eigenfunctions of the model, called Yangian Gelfand-Zetlin basis, to a l…