Graduate School of Science and Engineering Department of Physics

Job title

Assistant Professor

Research funding number

20323264

ORCID ID

0000-0002-1070-6336

Profile

Adiabatic cycles may induce nontrivial changes in quantum systems. A famous example is Berry's phase, which is also called as a phase holonomy. Besides, (quasi-)eigenenergies and eigenspaces of stationary states also exhibit nontrivial change, which is referred to as exotic quantum holonomy. I am investigating this phenomenon in various physical systems, and seeking its topological structure.

Functional Analysis and Operator Theory for Quantum Physics. A Festschrift in Honor of Pavel Exner, eds.J. Dittrich, H. Kovařík, A. Laptev (EMS Publ. House) 531-542 May 2017 [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...

New Journal of Physics 18 45023-1-45023-7 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...

Physical Review A 93(4) 042105-1-042105-5 Apr 2016 [Refereed]

It is shown that adiabatic cycles excite a quantum particle, which is confined in a one-dimensional region and is initially in an eigenstate. During the cycle, a -wall is applied and varied its strength and position. After the completio...

Physics Letters A 379(30-31) 1693-1698 Sep 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 vecto...

Physical Review E 89(4) 42904-1-42904-8 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...

Journal of Physics A: Mathematical and Theoretical 46(31) 315302-1-315302-17 Jul 2013 [Refereed]

An interplay of an exotic quantum holonomy and exceptional points is examined in one-dimensional Bose systems. The eigenenergy anholonomy, in which Hermitian adiabatic cycle induces nontrivial change in eigenenergies, can be interpreted as a manif...

Physical Review A 87(6) 062113-1-062113-6 Jun 2013 [Refereed]

We examine a parametric cycle in the N-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 holonomy,...

Akiyuki Ishikawa, Atushi Tanaka, Kensuke S. Ikeda and Akira Shudo

Physical Review E 86(3) 036208-1-036208-14 Sep 2012 [Refereed]

The role of diffraction is investigated for two-dimensional area-preserving maps with sharply or almost sharply divided phase space, in relation to the issue of dynamical tunneling. The diffraction effect is known to appear in general when the sys...

Journal of Physics A: Mathematical and Theoretical 45(33) 335305-1-335305-20 Jul 2012 [Refereed]

A set of gauge invariants are identified for the gauge theory of quantum anholonomies, which comprise both the Berry phase and an exotic anholonomy in eigenspaces. We examine these invariants for hierarchical families of quantum circuits whose qub...

Journal of the Physical Society of Japan 80(12) 125002-1-125002-2 Nov 2011 [Refereed]

A proof of the adiabatic theorem for quantum systems whose time evolution proceeds along discrete time, e.g., quantum maps and quantum circuits, is shown.