Specially-appointed Professor and Professor Emeritus
Institute of Science Tokyo, Japan
I am no longer accepting students or postdocs due to my retirement.
I am a theoretical physicist. The following are my main contributions.
[Spin glass theory]
Spin glass is a magnetic material with an extremely complex state of microscopic constituents. Its analysis is notoriously difficult. I discovered the exact solution to the spin glass problem in a specific part of the phase diagram in my thesis work. This theoretical framework has turned out to be crucial for addressing a wide range of topics including quantum error correction, statistical (Bayesian) inference, quantum state preparation (see also here), and even an April fool's joke 😄.
[Quantum annealing]
Quantum annealing is a framework (metaheuristic) for finding the optimal solution among many possibilities using quantum mechanical effects. We proposed and tested the idea of quantum annealing, which has now blossomed into an active field of research and development. The initial proposal was driven by pure academic curiosity, and recent advances have been mesmerizing as the field has evolved far beyond mere theoretical construction.
Our paper on quantum annealing was referred to in the document by the Nobel Committee as one of the important developments related to the Nobel Prize in Physics 2024.
August 25, 2026.
I recently wrote a paper on the spin glass problem. This study was completed following an extended dialogue with truly superhuman AIs (Opus 4.8, Opus 5, Fable 5, GPT 5.5, and GPT 5.6 sol). They proved to be highly proficient in both analytical and numerical computations, making it a remarkable experience. The era in which AI replaces even theoretical physicists might be just around the corner. For more details, please see my post on LinkedIn here and here.