6 papers
W*-algebraic Integration Theory
Jan GÅowacki, Yui Kuramochi
Given a pair of -algebras with separable, a measurable space and…
Asymptotically tight security analysis of quantum key distribution based on universal source compression
Takaya Matsuura, Shinichiro Yamano, Yui Kuramochi +2
Practical quantum key distribution (QKD) protocols require a finite-size security proof. The phase error correction (PEC) approach is one of the general strategies for security ana…
Universal tradeoff relations between resource cost and irreversibility of channels: General-resource Wigner-Araki-Yanase theorems and beyond
Hiroyasu Tajima, Koji Yamaguchi, Ryuji Takagi +1
Quantum technologies offer exceptional -- sometimes almost magical -- speed and performance, yet every quantum process costs physical resources. Designing next-generation quantum d…
Universal trade-off structure between symmetry, irreversibility, and quantum coherence in quantum processes
Hiroyasu Tajima, Ryuji Takagi, Yui Kuramochi
Symmetry, irreversibility, and quantum coherence are foundational concepts in physics. Here, we present a universal tradeoff relation between these three concepts. This particularl…
Tight concentration inequalities for quantum adversarial setups exploiting permutation symmetry
Takaya Matsuura, Shinichiro Yamano, Yui Kuramochi +2
We developed new concentration inequalities for a quantum state on an -qudit system or measurement outcomes on it that apply to an adversarial setup, where an adversary prepares…
Nonstandard derivation of the Gorini-Kossakowski-Sudarshan-Lindblad master equation of a quantum dynamical semigroup from the Kraus representation
Yui Kuramochi
We give a new nonstandard proof of the well-known theorem that the generator of a quantum dynamical semigroup on a finite-dimensional quantum system has a specific f…