Taksu Cheon

J-GLOBAL         Last updated: May 11, 2016 at 14:22
 
Avatar
Name
Taksu Cheon
Affiliation
Kochi University of Technology
Section
School of Environmental Science and Engineering / Research Institute, Laboratory for unified quantum devices
Job title
Professor, Lab Head
Degree
BSc (Univ. Tokyo, 1980), Ph.D. (Univ. Tokyo, 1985)

Profile

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.

What's new

 
 

Published Papers

 
Taksu Cheon, Sergey S. Poghosyan
   Dec 2015   [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
   Dec 2015   [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...
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...

Misc

 
Taksu Cheon
U.P.- Bulletin of Tokyo University Press      Jan 2015   [Refereed][Invited]
Tanaka Atushi, Cheon Taksu
Meeting abstracts of the Physical Society of Japan   69(2)    Aug 2014
Cheon Taksu, Poghosyan Sergey
Meeting abstracts of the Physical Society of Japan   69(2)    Aug 2014
Tanaka Atushi, Kim Sang Wook, Cheon Taksu
Meeting abstracts of the Physical Society of Japan   69(1)    Mar 2014
Kimura Yosuke, Tanioka Ryosuke, Matumoto Naoki, Cheon Taksu
Meeting abstracts of the Physical Society of Japan   68(1)    Mar 2013

Books etc

 
Takuju Zen (Taksu Cheon)
University of Tokyo Press   Sep 2014   ISBN:4130636073
A. Iqbal, T. Cheon (Part:Contributor, Ch. 13 "Evolutionary stability in quantum games")
Imperial College Press   Sep 2008   ISBN:1848162677

Conference Activities & Talks

 
New anatomy of quantum holonomy [Invited]
Taksu Cheon
KEK Research workshop"Development of Path-integral Formalism"   Feb 2009   
Quantum Bayesian Nash Equilibria and Bell Inequalities
Taksu Cheon
International Confernce on Quantum, Nano and Micro technologies (Martinique, Franch Antille)   Feb 2008   
Quantum Game: Bayesian Nash Equilibria and Bell Inequalities [Invited]
Taksu Cheon
9th Japan-Slovenia Seminar on Nonlinear Sciences (Osaka City U)   Nov 2007   
Quantum game/ Nash equilibria and Bell inequality [Invited]
Taksu Cheon
イノヴェイティヴコンピューティング調査研究会第1回講演会「量子力学とシステム情報制御」 (兵庫県立大学)   Jul 2007   
Bayesian Nash equilibria and Bell inequalities [Invited]
Taksu Cheon
KEK理論物理研究会「安定と不安定」 (高エネルギー加速器研究機構)   Mar 2007   

Works

 
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
この電子ノートは、高知工科大の大学院で平成15年度第1クオーターに行なわれた講義「自然科学と人間」の後半部分ために用意され素材を、進化ゲーム理論と生態系の数理に興味を持つ好事家のために公開したものです。前提知識はいりません。本当は微分方程式について知っていると深くわかりますが、知らなくてもかまいません。むしろテクニカルな部分は意図的に表に出さないように試みています。必要なのは冗談とまじめを同時に受け入れられ、かつその2つの区別ができることかもしれません。つまりは思考し判断する頭。まじめな学...

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
(1)通常のゲーム理論は二名のプレーヤーの戦略をそれぞれ独立した確率で表して定式化される。これを二名のプレーヤーの戦略を連結確率として表す型に書き換え,この連結確率を,通常のようにここのプレーヤーの戦略確率の積に限らず,一般的な非分離型で書くという,新しいゲーム理論の定式化を考えた。
(2)これをスーザニー型の複数タイププレーヤーのある非完備情報ゲームに適用して,この連結戦略を陽に量子状態で書く代わりに,一般的な和則や訂プレーヤー間の通信の欠如を表す「局所性」の仮定を置いて制限すると,連結...
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 2001 - Mar 2004    Investigator(s): Zen Takuju
本研究では、グラフの量子論、すなわち複数の一次元的直線を接点で接続した構造物上に存在する量子的粒子の運動についての研究を行った。これは、量子で細線デバイスを理想化した数学的モデルであり、さらには量子計算のための素子ともなりうる事が期待される系である。量子グラフには通常の量子力学では見られず、「場の量子論」にのみ出てくるよう様々な奇妙な現象が隠されていることが、これまでの筆者の研究で明らかになっている。本研究において、そのような諸現象の背後にパラメータ空間のU(N)多様体構造があって、その非...
Ministry of Education: Grant-in-Aid, Basic Research (C)
Project Year: Apr 1998 - Mar 2001    Investigator(s): Zen Takuju
本研究では、内部に点状相互作用を含んだ1、2次元のビリヤード系の量子力学の数理的性質を詳細に調べ、この系にはその非常な単純さにもかかわらず幾つかの興味深い特異な性質が存する事を解明した。まず、これまでにも比較的良く調べられてきた二次元量子ビリヤード系における量子カオス的順位統計については、量子カオス出現の条件の簡潔な解析的表式を得ることが出来た。さらに一次元量子系における点状相互作用について、通常のデルタ函数とは異なる波動函数そのものに非連続性をもたらす「第二種の点状相互作用」というべきも...