6 papers
Subspace-Protected Topological Phases and Bulk-Boundary Correspondence
Kenji Shimomura, Ryo Takami, Daichi Nakamura +1
While tremendous research has revealed that symmetry enriches topological phases of matter, more general principles that protect topological phases have yet to be explored. In this…
Hopf Bifurcation of Nonlinear Non-Hermitian Skin Effect
Kohei Kawabata, Daichi Nakamura
The non-Hermitian skin effect, nonreciprocity-induced anomalous localization of an extensive number of eigenstates, represents a hallmark of non-Hermitian topological systems with…
Nonsymmorphic Topological Phases of Non-Hermitian Systems
Daichi Nakamura, Yutaro Tanaka, Ken Shiozaki +1
Non-Hermiticity appears ubiquitously in various open classical and quantum systems and enriches classification of topological phases. However, the role of nonsymmorphic symmetry, c…
Non-Hermitian Hopf insulators
Daichi Nakamura, Kohei Kawabata
Hopf insulators represent a unique class of topological insulators that exist exclusively in two-band systems and are inherently unstable upon the inclusion of additional bands. Me…
Callan-Rubakov effects in topological insulators
Yusuke O. Nakai, Reuel Dsouza, Daichi Nakamura +3
The Callan-Rubakov effect describes monopole-catalyzed proton decay. While this effect is fundamental for quantum field theories, its experimental observation has remained far from…
Exceptional second-order topological insulators
Yutaro Tanaka, Daichi Nakamura, Ryo Okugawa +1
Point-gap topological phases of non-Hermitian systems exhibit exotic boundary states that have no counterparts in Hermitian systems. Here, we develop classification of second-order…