209 citations · 1.6k across the 96 of their papers we have counts for
97 papers
The algebro-geometric aspect of the iterated limit of a quaternary of means of four terms
Keiji Matsumoto, Ryunosuke Nakano
We study the iterated limit of a quaternary of means of four terms through the period map from the family of cyclic fourfold coverings of the complex projective line branching at s…
Analogies of Jacobi's formula
Keiji Matsumoto
By considering Schwarz's map for the hypergeometric differential equation with parameters or , we give some analogies of Jacobi's formula $\var…
An analogy of Jacobi's formula and its applications
Jun Chiba, Keiji Matsumoto
We give an analogy of Jacobi's formula, which relates the hypergeometric function with parameters and theta constants. By using this analogy and twice formulas of the…
A Geometrical Approach to Quantum Estimation Theory
Keiji Matsumoto
This post is the author's doctoral dissertation back in 1997. The dissertation covers following four kinds of problems: First, it studies achievable Cramer-Rao type bounds of vario…
Undecidability of the fate of relaxation in one-dimensional quantum systems
Naoto Shiraishi, Keiji Matsumoto
We investigate the relaxation dynamics in an isolated quantum many-body system. The stationary value of an observable after relaxation is a topic of researches in the field of quan…
Undecidability in quantum thermalization
Naoto Shiraishi, Keiji Matsumoto
The investigation of thermalization in isolated quantum many-body systems has a long history, dating back to the time of developing statistical mechanics. Most quantum many-body sy…