3 papers
math-ph2022
Spectral mapping theorem of an abstract non-unitary quantum walk
Keisuke Asahara, Daiju Funakawa, Etsuo Segawa +2
This paper continues the previous work (Quantum Inf. Process (2019)) by two authors of the present paper about a spectral mapping property of chiral symmetric unitary operators. In…
math-ph2020
The Witten Index for One-dimensional Non-unitary Quantum Walks with Gapless Time-evolution
Keisuke Asahara, Daiju Funakawa, Motoki Seki +1
Recent developments in the index theory of discrete-time quantum walks allow us to assign a certain well-defined supersymmetric index to a pair of a unitary time-evolution and…
math-ph2018
Spectral analysis of an abstract pair interaction model
Keisuke Asahara, Daiju Funakawa
We consider an abstract pair-interaction model in quantum field theory with a coupling constant and analyze the Hamiltonian of the model. In the massive c…