Taksu Cheon

J-GLOBAL         Last updated: Dec 25, 2019 at 00:43
Taksu Cheon
Kochi University of Technology
School of Environmental Science and Engineering
Job title
Professor, Dean, Graduate School of Engineering & School of Engineering
BSc (Univ. Tokyo, 1980), Ph.D. (Univ. Tokyo, 1985)
Research funding number


Inside the red brick building overlooking a subtropical garden in the Tosa Yamada campus, Kochi University of Technology in idyllic southeast Japan, Taksu Cheon is exploring uncharted dark corners of quantum mechanics, the universal law of microscopic world. His recent focus is on the quantum graph, which is a theoretical laboratory for exotic quantum phenomena in the simplest of settings, and a useful mathematical model of futuristic single-electron devices based on quantum wire. He is also interested in developing a unified theory of quantum holonomy that comprises both the celebrated Berry phase and its newly found twin, the exotic spiral holonomy.

We live only to discover beauty. All else is a form of waiting. (Kahlil Gibran)

Taksu Cheon, a native of the ancient city of Kyoto, graduated in Physics from the University of Tokyo. He earned his PhD also from the University of Tokyo in the area of theoretical nuclear physics. His career path has traversed several research institutions in Japan and United States, including Hosei University, the University of Georgia, and the University of Maryland. He is currently Professor of Theoretical Physics at the Kochi University of Technology.

Books etc

Quantum mechanical approach to system and control
Mar 2018   ISBN:4339033561
Takuju Zen (Taksu Cheon)
University of Tokyo Press   Sep 2014   ISBN:4130636073
A. Iqbal, T. Cheon (Part:Contributor, pp.251-290, Ch. 13 "Evolutionary stability in quantum games")
Imperial College Press   Sep 2008   ISBN:1848162677

Published Papers

Atushi Tanaka, Takaaki Nakamura, Taksu Cheon
   Dec 2019   [Refereed]
It is shown that the ground state of weakly interacting Bose particles in a quasi one-dimensional box trap can be converted into an excited stationary state by an adiabatic cyclic operation that involves a quench of interaction strength: A sharp i...
Serge Galam, Taksu Cheon
Entropy   22 25-(19pp)   Jan 2020   [Refereed]
Asymmetry in contrarian behavior is investigated within the Galam model of opinion dynamics using update groups of size 3 with two competing opinions A and B. Denoting Tex and Tex the respective proportions of A and B contrarians, fourschemes of i...
Axel Pérez-Obiol, Taksu Cheon
   Nov 2019   [Refereed]
We consider the solution of the quantum Coulomb problem in one dimension with the most general connection condition at the origin. The divergence of the derivative of the wave function at the origin invalidates the standard current conservation ap...
Axel Perez-Obiol and Taksu Cheon
   Jul 2019   [Refereed]
We consider a Bose-Einstein condensate with repulsive interactions confined in a 1D ring where a Dirac delta is rotating at constant speed. The spectrum of stationary solutions is analyzed in terms of the nonlinear coupling, delta velocity, and de...
Serge Galam, Taksu Cheon
   Jan 2019   [Refereed]
Sudden and unexpected changes in the dynamics of public opinion while facing a decisive issue seem to be inherently unpredictable as with the outbreak of street protests and eventual social uprisings as well as odd voting outcomes. Respective illu...
Axel Perez-Obiol, Taksu Cheon
J. Phys. Soc. Jpn.   88 034005-(7pp)   Feb 2019   [Refereed]
All possible Tex and Tex boundary conditions are considered at the defect, computing for each of them the real eigenfunctions, written as Jacobi elliptic functions, and eigenvalues for the ground state and first few excited energy level...
Taksu Cheon, Serge Galam
Phys. Lett. A   382 1509-1515   Jun 2018   [Refereed]
We introduce a model of temporal evolution of political opinions which amounts to a dynamical extension of Galam model in which the number of inflexibles are treated as dynamical variables. We find that the critical value of inflexibles in the o...
Takaaki Nakamura, Taksu Cheon
J. Phys. Soc. Jpn.   86 114001-(5pp)   Feb 2018   [Refereed]
The stationary states of nonlinear Schr{ö}dinger equation on a ring with a defect is numerically analyzed. Unconventional connection conditions are imposed on the point defect, and it is shown that the system displays energy level crossings and...
Atushi Tanaka, Taksu Cheon
Bulletine of Physical Society of Japan   72(4) 240-245   Apr 2017   [Refereed][Invited]
Several examples of systems that exhibits exotic quantum holonomy are reviewed. Related theoretical works are briefly explained.
Taksu Cheon, Sergey S. Poghosyan
Physica A   469 353-362   Feb 2017   [Refereed]
We introduce the concept of metaasabiya, the second non-material resource, to the asabiya theory of historical dynamics. We find that the resulting three variable dynamical system has peculiar structures of the repeller axis, the attractor string...
Atushi Tanaka, Taksu Cheon
Functional Analysis and Operator Theory for Quantum Physics. A Festschrift in Honor of Pavel Exner, eds.J. Dittrich, H. Kovarik, A. Laptev   531-542   Dec 2016   [Refereed][Invited]
An adiabatic time evolution of a closed quantum system connects eigenspaces of initial and final Hermitian Hamiltonians for slowly driven systems, or, unitary Floquet operators for slowly modulated driven systems. We show that the connection of e...
Taksu Cheon, Sergey S. Poghosyan
Bulletin of Kochi University of Technology   13 105-114   Jul 2016   [Refereed]
It is shown that any Hermitian operator can be expanded in terms of a set of operator formed from bi-orthogonal basis, and the expansion coefficients are given as products of weight functions and weak values, shedding a new light on the physical i...
Atushi Tanaka, Taksu Cheon
New J. Phys.   18 045023-(7)   Apr 2016   [Refereed][Invited]
We show that an adiabatic cycle excites Bose particles confined in a one-dimensional box. During the adiabatic cycle, a wall described by a Tex-shaped potential is applied and its strength and position are slowly varied. When the system is ...
Taksu Cheon, Jun Morimoto
Phys. Lett. A   380 429-434   Jan 2016   [Refereed]
We introduce a novel type of contrarian agent, the balancer, to Galam model of opinion dynamics, in order to account for the skepticism over one-sidedness and for the sense of fairness. We find that the inclusion of balancers along with floaters ...
Taksu Cheon
J. Kor. Phys. Soc.   67 777-784   Sep 2015   [Refereed]
Wigner's marginal probability theory is revisited, and systematically applied to n-particle correlation measurements. A set of Bell inequalities whose corollaries are Hardy contradiction and its generalisation are derived with intuitive graphical...
Taksu Cheon, Sergey S. Poghosyan
J. Phys. Soc. Jpn.   84 064006-(8pp)   Jun 2015   [Refereed]
We introduce a double-stranded Kronig-Penney model, and analyse its transport properties. The asymmetric fluxes between two strands with suddenly alternating localization patterns are found as the energy is varied. The zero-size limit of the int...
Atushi Tanaka, Taksu Cheon
Phys. Lett. A   379 1693-1698   May 2015   [Refereed]
A topological formulation of the eigenspace anholonomy, where eigenspaces are interchanged by adiabatic cycles, is introduced. The anholonomy in two-level systems is identified with a disclination of the director (headless vector) of a Bloch vect...
Ondrej Turek, Taksu Cheon
Linear Algebra & its Applications   469 569-593   Jan 2015   [Refereed]
We study Hermitian unitary matrices Tex with the following property: There exist Tex and Tex such that the entries of Tex satisfy Tex and Tex for all $j,k=1,...
Atushi Tanaka, Sang Wook Kim, Taksu Cheon
Phys. Rev. E   89 042904-(8pp)   Apr 2014   [Refereed]
The correspondence between exotic quantum holonomy that occurs in families of Hermitian cycles, and exceptional points (EPs) for non-Hermitian quantum theory is examined in quantum kicked tops. Under a suitable condition, an explicit expressions o...
Sergey S. Poghosyan and Taksu Cheon
J. Phys. Soc. Jpn.   83 044004-(8pp)   Apr 2014   [Refereed]
We study a set of scattering matrices of quantum graphs containing minimal number of passbands, i.e., maximal number of zero elements. The cases of even and odd vertex degree are considered. Using a solution of inverse scattering problem, we reco...

Conference Activities & Talks

Nakamura Takaaki, Kawamata Masahiro, Cheon Taksu
Meeting Abstracts of the Physical Society of Japan   2017   
Tanaka Atushi, Cheon Taksu
Meeting Abstracts of the Physical Society of Japan   2017   
<p>新奇な量子ホロノミーを応用し、多粒子系の準位反転状態と呼ばれる非平衡状態を断熱サイクルから生成する方法を報告する。対象とする系は、ポテンシャルに捕捉された弱く相互作用するボーズ粒子系であり、その基底状態を始状態とする。断熱サイクルではデルタ関数状のポテンシャルを印加し、その強度と位置を変化させたあとで、これを取り除く。終状態では、一粒子系の第一励起状態を全粒子が占有する意味で、準位反転が実現する。Ref. arXiv:1512.07946; New J. Phys 18, 04502...
Quantum vertices: Theory and applications [Invited]
Taksu Cheon
3rd Dynamics Days in Central Asia (Astana)   5 Sep 2016   
Spiral orbits and oscillations in historical evolution of empires [Invited]
Taksu Cheon
Colloqium, Dept. of Mathematics, Nazarbayev University   1 Sep 2016   
Morimoto J., Cheon T.
日本物理学会講演概要集   19 Mar 2016   
Nakamura Takaaki, Turek Ondrej, Cheon Taksu
Meeting Abstracts of the Physical Society of Japan   2016   
Morimoto Jun, Cheon Taksu
日本物理学会講演概要集   16 Sep 2015   
Tanaka Atushi, Cheon Taksu
日本物理学会講演概要集   16 Sep 2015   
Cheon Taksu, Poghosyan Sergey
Meeting abstracts of the Physical Society of Japan   22 Aug 2014   
Tanaka Atushi, Cheon Taksu
Meeting abstracts of the Physical Society of Japan   22 Aug 2014   


Taksu Cheon
U.P.- Bulletin of Tokyo University Press      Jan 2015   [Refereed][Invited]
Singular point and one-dimensional quantum mechanics
Taksu Cheon, Izumi Tsutsui
別冊・数理科学「量子の新世紀」(サイエンス社)   2006-4 197-207   Apr 2006   [Invited]
Taksu Cheon
Suri Kagaku   40(11) 54-62   Nov 2002   [Invited]
応用物理教育   24(1)    2000   [Invited]


Taksu Cheon   Educational Materials   Jan 2006
This electronic lecture covers the theory of "quantum graph", which is one of the main subject under current research at the Mathematical Engineering Laboratory/ Theoretical Physics Group at Kochi University of Technology. The lecture is based on...
Taksu Cheon   Educational Materials   Jan 2005
This electronic lecture note on the cellular automaton models of traffic flow is an outgrowth of the materials pepared for the seminars and study meetings of the Mathematical Engineering Laboratory (aka, Theoretical Physics Group) at the Graduate ...
Taksu Cheon   Educational Materials   Jan 2004
This eNote is a translation of my lecture note prepared for a course in the first and second quaters of academic year 2003 at Graduate School, Kochi University of Technology. This is made open in the hope to attract general public to the emerging ...
全卓樹   Educational Materials   Nov 2003

Research Grants & Projects

Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 2015 - Mar 2018    Investigator(s): Zen Takuju
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 2012 - Mar 2015    Investigator(s): Zen Takuju
We have studied the singular vertex of quantum graphs, which is the basic building block in quantum graph theory. We have performed its mathematical analysis and classification and its physical characterization. In the process, we have establishe...
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 2009 - Mar 2012    Investigator(s): Zen Takuju
The exotic quantum holonomy refers to the anholonomy of quantum states other than that of the quantum phases. It involves the exchange of eigenstates after the cyclic variation of system parameters. We have created a gauge theoretical formulation ...
Ministry of Education: Grant-in-Aid, Special Guest Researcher Fund
Project Year: Sep 2006 - Mar 2008    Investigator(s): Zen Takuju
ゲーム理論の量子的拡張である量子ゲームの研究を行った。古典戦略に比したときの量子戦略の利点が明確になるような量子ゲームの定式化を試みて、次の二点の成果を得た。 1)量子ゲームを、ヒルベルトベクトルを直接用いずに、確率分布の用語のみを使って表現する手法を開拓した。この場合に鍵となったのは、非分離型の連合確率(nonfactorizable jointy probability)である。これによって量子戦略というものの物理的内容が明確になるとともに、量子ゲーム的設定をどのようにして実現できるか...
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 2006 - Mar 2009    Investigator(s): Zen Takuju
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 2001 - Mar 2004    Investigator(s): Zen Takuju
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 1998 - Mar 2001    Investigator(s): Zen Takuju