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Time-crystalline long-range order in chiral fermionic vacuum
Nobuyuki Okuma
It is widely believed that there is no macroscopic time-crystalline order in the ground states of short-range interacting systems. In this paper, we consider a time-dependent corre…
Time-crystalline long-range order in squeezed ground state
Nobuyuki Okuma
It is widely believed that ground-state time crystals are not realizable in realistic macroscopic systems. In particular, Watanabe and Oshikawa proved a theorem that implies the ab…
Non-normal Hamiltonian dynamics in quantum systems and its realization on quantum computers
Nobuyuki Okuma, Yuya O. Nakagawa
The eigenspectrum of a non-normal matrix, which does not commute with its Hermitian conjugate, is a central issue of non-Hermitian physics that has been extensively studied in the…
Nontrivial interband effect: applications to magnetic susceptibility, nonlinear optics, and topological degeneracy pressure
Nobuyuki Okuma
The interband effect is an important concept both in traditional and modern solid-state physics. In this paper, we present a theory of the nontrivial interband effect, which cannot…