Professor, Dean, Graduate School of Engineering & School of Engineering
Degree
BSc (Univ. Tokyo, 1980), Ph.D. (Univ. Tokyo, 1985)
Research funding number
60227353
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.
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...
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...
J. Phys. Soc. Jpn. 88 034005-(7pp) Feb 2019 [Refereed]
All possible and 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...
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...
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...
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...
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...
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...
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 -shaped potential is applied and its strength and position are slowly varied. When the system is ...
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 ...
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...
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...
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...
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...
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...
Acta Polytechnica (Prague) 53 410-415 Oct 2013 [Refereed][Invited]
We study a family of closed quantum graphs described by one singular vertex of order . By suitable choice of the parameters specifying the singular vertex, we can construct a closed sequence of paths in the parameter space that physically co...
J. Phys. A: Math. Theor. 46 315302-(17pp) Jul 2013 [Refereed]
An interplay of the exotic quantum holonomy and exceptional points is examined. The eigenenergy anholonomy, in which Hermitian adiabatic cycle induces nontrivial change in eigenenergies, can be interpreted as a manifestation of eigenenergy's Riem...
We examine a parametric cycle in the -body Lieb-Liniger model that starts from the free system and goes through Tonks-Girardeau and super-Tonks-Girardeau regimes and comes back to the free system. We show the existence of exotic quantum holon...
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
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...
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 ...
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 ...
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 ...
