Updated on 2025/03/18

写真a

 
KATO Kohtaro
 
Organization
Graduate School of Informatics Department of Mathematical Informatics 2 Assistant Professor
Graduate School
Graduate School of Informatics
Undergraduate School
School of Informatics Department of Natural Informatics
Title
Assistant Professor

Degree 1

  1. Ph.D. in Science ( 2017.3   The University of Tokyo ) 

 

Papers 16

  1. Universal validity of the second law of information thermodynamics

    Minagawa S., Mohammady M.H., Sakai K., Kato K., Buscemi F.

    npj Quantum Information   Vol. 11 ( 1 )   2025.12

     More details

    Publisher:npj Quantum Information  

    Adiabatic measurements, followed by feedback and erasure protocols, have often been considered as a model to embody Maxwell’s Demon paradox and to study the interplay between thermodynamics and information processing. Such studies have led to the conclusion, now widely accepted in the community, that Maxwell’s Demon and the second law of thermodynamics can peacefully coexist because any gain provided by the demon must be offset by the cost of performing the measurement and resetting the demon’s memory to its initial state. Statements of this kind are collectively referred to as second laws of information thermodynamics and have recently been extended to include quantum theoretical scenarios. However, previous studies in this direction have made several assumptions, particularly about the feedback process and the demon’s memory readout, and thus arrived at statements that are not universally applicable and whose range of validity is not clear. In this work, we fill this gap by precisely characterizing the full range of quantum feedback control and erasure protocols that are overall consistent with the second law of thermodynamics. This leads us to conclude that the second law of information thermodynamics is indeed universal: it must hold for any quantum feedback control and erasure protocol, regardless of the measurement process involved, as long as the protocol is overall compatible with thermodynamics. Our comprehensive analysis not only encompasses new scenarios but also retrieves previous ones, doing so with fewer assumptions. This simplification contributes to a clearer understanding of the theory.

    DOI: 10.1038/s41534-024-00922-w

    Scopus

  2. Port-based telecloning of an unknown quantum state

    Reiji Okada, Kohtaro Kato, Francesco Buscemi

    arXiv e-print     2025.1

     More details

    Language:English  

  3. Analysis of Discrete Modern Hopfield Networks in Open Quantum System

    Takeshi Kimura, Kohtaro Kato

    arXiv e-print     2024.11

     More details

    Authorship:Last author  

  4. Exact renormalization group flow for matrix product density operators

    Kohtaro Kato

    arXiv e-print     2024.10

     More details

    Authorship:Lead author   Language:English  

  5. Generic increase of observational entropy in isolated systems

    Nagasawa T., Kato K., Wakakuwa E., Buscemi F.

    Physical Review Research   Vol. 6 ( 4 )   2024.10

     More details

    Publisher:Physical Review Research  

    Observational entropy - a quantity that unifies Boltzmann's entropy, Gibbs' entropy, von Neumann's macroscopic entropy, and the diagonal entropy - was recently argued to play a key role in a modern formulation of statistical mechanics. Here, relying on algebraic techniques taken from Petz's theory of statistical sufficiency and on a Lévy-type concentration bound, we prove rigorous theorems showing how the observational entropy of a system undergoing a unitary evolution chosen at random tends to increase with overwhelming probability and to reach its maximum very quickly. More precisely, we show that for any observation that is sufficiently coarse with respect to the size of the system, regardless of the initial state of the system (be it pure or mixed), random evolution renders its state practically indistinguishable from the uniform (i.e., maximally mixed) distribution with a probability approaching 1 as the size of the system grows. The same conclusion holds not only for random evolutions sampled according to the unitarily invariant Haar distribution but also for approximate 2-designs, which are thought to provide a more physically and computationally reasonable model of random evolutions.

    DOI: 10.1103/PhysRevResearch.6.043327

    Scopus

▼display all

MISC 1

  1. トポロジカル量子計算とマヨラナ粒子 Invited

    数理科学4月号 マヨラナ粒子をめぐって   Vol. 60 ( 4 ) page: 58 - 64   2022.4

     More details

    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

Presentations 13

  1. Exact renormalization flow for matrix product density operators International conference

    Kato Kohtaro

    28th Quantum Information Processing Conference (QIP2025)  2025.2.25 

     More details

    Event date: 2025.2

    Language:English   Presentation type:Poster presentation  

    Country:United States  

  2. Generalized cluster expansion: an attempt to prove locality of effective Hamiltonians Invited International conference

    Kato Kohtaro

    Correlations of quantum many-body systems  2024.12.18 

     More details

    Event date: 2024.12

    Language:English   Presentation type:Oral presentation (invited, special)  

    Country:Germany  

  3. Exact and Local Compression of Quantum Bipartite States International conference

    Kato Kohtaro

    Quantum Extreme Universe: Matter, Information, and Gravity  2024.10.21 

     More details

    Event date: 2024.10

    Language:English   Presentation type:Poster presentation  

    Country:Japan  

  4. Non-abelian anyons in quantum information Invited

    Kato Kohtaro

    2024.9.26 

     More details

    Event date: 2024.9

    Language:English   Presentation type:Oral presentation (invited, special)  

    Country:Japan  

  5. Exact renormalization flow for matrix product density operators Invited International conference

    Kato Kohtaro

    Shenzhen-Nagoya Workshop on Quantum Science 2024  2024.9.21 

     More details

    Event date: 2024.9

    Language:English   Presentation type:Oral presentation (invited, special)  

    Country:Japan  

▼display all

KAKENHI (Grants-in-Aid for Scientific Research) 5

  1. トポロジカル量子計算機アーキテクチャの理論的研究

    Grant number:24H00829  2024.4 - 2027.3

    学術変革領域研究(B)

    加藤晃太郎

      More details

    Authorship:Principal investigator  Grant type:Competitive

    Grant amount:\23920000 ( Direct Cost: \18400000 、 Indirect Cost:\5520000 )

  2. 「エニオンの動的制御による情報技術の開拓」領域の総括

    Grant number:24H00826  2024.4 - 2027.3

    学術変革領域研究(B)

    橋坂 昌幸,吉岡 克将,加藤晃太郎

      More details

    Authorship:Coinvestigator(s)  Grant type:Competitive

    Grant amount:\14430000 ( Direct Cost: \11100000 、 Indirect Cost:\3330000 )

  3. 超伝導接合系におけるエニオン: マヨラナフェルミオンを超えて

    Grant number:23K17668  2023.6 - 2026.3

    挑戦的研究(萌芽)

    田仲 由喜夫,加藤 晃太郎,星野 晋太郎

      More details

    Authorship:Coinvestigator(s)  Grant type:Competitive

    Grant amount:\6240000 ( Direct Cost: \4800000 、 Indirect Cost:\1440000 )

  4. ギャップのある局所ハミルトニアン系に現れる多体相関の量子情報的解析

    Grant number:22K13972  2022 - 2024

    文部科学省  科学研究費助成事業  若手研究

      More details

    Authorship:Principal investigator  Grant type:Competitive

    Direct Cost: \1900000 、 Indirect Cost:\570000 )

  5. 量子情報理論的手法による1次元テンソルネットワークの数理的解析

    Grant number:22H05254  2022 - 2023

    文部科学省  科学研究費助成事業  学術変革領域研究(A)

      More details

    Authorship:Principal investigator  Grant type:Competitive

    Direct Cost: \900000 、 Indirect Cost:\270000 )

 

Academic Activities 1

  1. YITP international workshop "Quantum Information Entropy in Physics" International contribution

    Role(s):Planning, management, etc., Panel moderator, session chair, etc.

    加藤晃太郎 (Chair)   2022.3

     More details

    Type:Academic society, research group, etc.