309 citations · 3.5k across the 93 of their papers we have counts for
39 papers · 1 filter
Singular-Value Statistics of Non-Hermitian Random Matrices and Open Quantum Systems
Kohei Kawabata, Zhenyu Xiao, Tomi Ohtsuki +1
The spectral statistics of non-Hermitian random matrices are of importance as a diagnostic tool for chaotic behavior in open quantum systems. Here, we investigate the statistical p…
Deciphering quantum fingerprints in electric conductance
Shunsuke Daimon, Kakeru Tsunekawa, Shinji Kawakami +5
When the electric conductance of a nano-sized metal is measured at low temperatures, it often exhibits complex but reproducible patterns as a function of external magnetic fields,…
Application of Convolutional Neural Network to Quantum Percolation in Topological Insulators
Tomohiro Mano, Tomi Ohtsuki
Quantum material phases such as the Anderson insulator, diffusive metal, and Weyl/Dirac semimetal as well as topological insulators show specific wave functions both in real and Fo…
Multifractality and the distribution of the Kondo temperature at the Anderson transition
Keith Slevin, Stefan Kettemann, Tomi Ohtsuki
Using numerical simulations, we investigate the distribution of Kondo temperatures at the Anderson transition. In agreement with previous work, we find that the distribution has a…
Unconventional scaling theory in disorder-driven quantum phase transition
Xunlong Luo, Tomi Ohtsuki, Ryuichi Shindou
We clarify novel forms of scaling functions of conductance, critical conductance distribution and localization length in a disorder-driven quantum phase transition between band ins…
Comparative study of Weyl semimetal, topological and Chern insulators: thin-film point of view
Yukinori Yoshimura, Wataru Onishi, Koji Kobayashi +2
Regarding three-dimensional (3D) topological insulators and semimetals as a stack of constituent 2D topological (or sometimes non-topological) layers is a useful viewpoint. Primari…
Engineering Dirac electrons emergent on the surface of a topological insulator
Yukinori Yoshimura, Koji Kobayashi, Tomi Ohtsuki +1
The concept of topological insulator (TI) has introduced a new point of view to condensed-matter physics, relating a priori unrelated subfields such as quantum (spin, anomalous) Ha…
Modification and Control of Topological Insulator Surface States Using Surface Disorder
Vincent Sacksteder, Tomi Ohtsuki, Koji Kobayashi
We numerically demonstrate a practical means of systematically controlling topological transport on the surface of a three dimensional topological insulator, by introducing strong…
Dimensional crossover of transport characteristics in topological insulator nanofilms
Koji Kobayashi, Yukinori Yoshimura, Ken-Ichiro Imura +1
We show how the two-dimensional (2D) topological insulator evolves, by stacking, into a strong or weak topological insulator with different topological indices, proposing a new con…
Experimental Proof of Universal Conductance Fluctuation in Quasi-1D Epitaxial BiSe Wires
Sadashige Matsuo, Kensaku Chida, Daichi Chiba +8
We report on conductance fluctuation in quasi-one-dimensional wires made of epitaxial BiSe thin film. We found that this type of fluctuation decreases as the wire lengt…
Density of States Scaling at the Semimetal to Metal Transition in Three Dimensional Topological Insulators
Koji Kobayashi, Tomi Ohtsuki, Ken-Ichiro Imura +1
The quantum phase transition between the three dimensional Dirac semimetal and the diffusive metal can be induced by increasing disorder. Taking the system of disordered $\mathbb{Z…
Critical exponent for the Anderson transition in the three dimensional orthogonal universality class
Keith Slevin, Tomi Ohtsuki
We report a careful finite size scaling study of the metal insulator transition in Anderson's model of localisation. We focus on the estimation of the critical exponent that de…
Disordered weak and strong topological insulators
Koji Kobayashi, Tomi Ohtsuki, Ken-Ichiro Imura
A global phase diagram of disordered weak and strong topological insulators is established numerically. As expected, the location of the phase boundaries is renormalized by disorde…
Finite-size energy gap in weak and strong topological insulators
Ken-Ichiro Imura, Mayuko Okamoto, Yukinori Yoshimura +2
The non-trivialness of a topological insulator (TI) is characterized either by a bulk topological invariant or by the existence of a protected metallic surface state. Yet, in reali…
Finite Size Scaling of the Chalker-Coddington Model
Keith Slevin, Tomi Ohtsuki
In Ref.1 (Physical Review B 80, 041304(R) (2009)), we reported an estimate of the critical exponent for the divergence of the localization length at the quantum Hall transition tha…
Conductance distributions in disordered quantum spin-Hall systems
K. Kobayashi, T. Ohtsuki, H. Obuse +1
We study numerically the charge conductance distributions of disordered quantum spin-Hall (QSH) systems using a quantum network model. We have found that the conductance distributi…
Finite Size Scaling Analysis of the Anderson Transition
Bernhard Kramer, Angus MacKinnon, Tomi Ohtsuki +1
This chapter describes the progress made during the past three decades in the finite size scaling analysis of the critical phenomena of the Anderson transition. The scaling theory…
Point-Contact Conductance in Asymmetric Chalker-Coddington Network Model
Koji Kobayashi, Tomi Ohtsuki, Keith Slevin
We study the transport properties of disordered two-dimensional electron systems with a perfectly conducting channel. We introduce an asymmetric Chalker-Coddington network model an…
Conductance plateau transitions in quantum Hall wires with spatially correlated random magnetic fields
Tohru Kawarabayashi, Yoshiyuki Ono, Tomi Ohtsuki +3
Quantum transport properties in quantum Hall wires in the presence of spatially correlated disordered magnetic fields are investigated numerically. It is found that the correlation…
Transport properties in network models with perfectly conducting channels
Koji Kobayashi, Kosuke Hirose, Hideaki Obuse +2
We study the transport properties of disordered electron systems that contain perfectly conducting channels. Two quantum network models that belong to different universality classe…
Chalker-Coddington model described by an S-matrix with odd dimensions
Kosuke Hirose, Tomi Ohtsuki, Keith Slevin
The Chalker-Coddington network model is often used to describe the transport properties of quantum Hall systems. By adding an extra channel to this model, we introduce an asymmetri…
Unconventional conductance plateau transitions in quantum Hall wires with spatially correlated disorder
Tohru Kawarabayashi, Yoshiyuki Ono, Tomi Ohtsuki +3
Quantum transport properties in quantum Hall wires in the presence of spatially correlated random potential are investigated numerically. It is found that the potential correlation…
Mesoscopic Hall effect driven by chiral spin order
Jun-ichiro Ohe, Tomi Ohtsuki, Bernhard Kramer
A Hall effect due to spin chirality in mesoscopic systems is predicted. We consider a 4-terminal Hall system including local spins with geometry of a vortex domain wall, where stro…
Quantum transport phenomena in disordered electron systems with spin-orbit coupling in two dimensions and below
Yoichi Asada, Keith Slevin, Tomi Ohtsuki
Electron transport phenomena in disordered electron systems with spin-orbit coupling in two dimensions and below are studied numerically. The scaling hypothesis is checked by analy…