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Dynamical quantum phase transitions (DQPTs) are topologically characterized in quantum quench dynamics in topological systems. In this paper, we study Loschmidt amplitudes and DQPTs in quantum quenches in mirror-symmetric topological…

Mesoscale and Nanoscale Physics · Physics 2021-10-26 Ryo Okugawa , Hiroki Oshiyama , Masayuki Ohzeki

We study second-order topological insulators and semimetals characterized by chiral symmetry. We investigate topological phase transitions of a model for construction of the two-dimensional second-order topological insulators protected only…

Mesoscale and Nanoscale Physics · Physics 2019-12-06 Ryo Okugawa , Shin Hayashi , Takeshi Nakanishi

Topological insulators (TIs) are promising for achieving dissipationless transport devices due to the robust gapless states inside the insulating bulk gap. However, currently realized 2D TIs, quantum spin Hall (QSH) insulators, suffer from…

An acoustic topological insulator (TI) is synthesized using topology optimization, a free material inverse design method. The TI appears spontaneously from the optimization process without imposing requirements on the existence of pseudo…

Mesoscale and Nanoscale Physics · Physics 2019-06-19 Rasmus E. Christiansen , Fengwen Wang , Ole Sigmund

Topological phases enable protected transport along the edges of materials, offering immunity against scattering from disorder and imperfections. These phases were suggested and demonstrated not only for electronic systems, but also for…

The classification of topological insulators predicts the existence of high-dimensional topological phases that cannot occur in real materials, as these are limited to three or fewer spatial dimensions. We use electric circuits to…

Mesoscale and Nanoscale Physics · Physics 2020-06-03 You Wang , Hannah M. Price , Baile Zhang , Y. D. Chong

Three dimensional topological insulator represents a class of novel quantum phases hosting robust gapless boundary excitations, which is protected by global symmetries such as time reversal, charge conservation and spin rotational symmetry.…

Mesoscale and Nanoscale Physics · Physics 2014-03-25 Yuan-Ming Lu , Dung-Hai Lee

We start by describing a symmetry enforced nodal line semi-metal (NLSM) in the 2D flat form of honeycomb Group - V and its non trivial thermo-electric response. We will then proceed to show that, upon buckling, the system undergoes its…

Materials Science · Physics 2022-02-15 Santosh Kumar Radha

The topological phases of matter are characterized using the Berry phase, a geometrical phase, associated with the energy-momentum band structure. The quantization of the Berry phase, and the associated wavefunction polarization, manifest…

Higher-order topological insulator, as a newly found non-trivial material and structure, possesses a topological phase beyond the bulk-boundary correspondence. Here, we present an experimental observation of photonic higher-order…

We consider a metasurface consisting of a square lattice of cylindrical antidots in a two-dimensional topological insulator (2DTI). Each antidot supports a degenerate Kramer's pair of eigenstates formed by the helical topological edge…

Mesoscale and Nanoscale Physics · Physics 2021-10-13 Fedor Nigmatulin , Ivan Shelykh , Ivan Iorsh

We present a theoretical study and experimental realization of a system that is simultaneously a four-dimensional (4D) Chern insulator and a higher-order topological insulator (HOTI). The system sustains the coexistence of (4-1)-dimensional…

Applied Physics · Physics 2021-02-03 Ze-Guo Chen , Weiwei Zhu , Yang Tan , Licheng Wang , Guancong Ma

As the thickness of a three-dimensional (3D) topological insulator (TI) becomes comparable to the penetration depth of the surface states, quantum tunneling between surfaces turns their gapless Dirac electronic structure into a gapped…

Mesoscale and Nanoscale Physics · Physics 2020-04-13 Su Kong Chong , Lizhe Liu , Taylor D. Sparks , Feng Liu , Vikram V. Deshpande

Meeting of non-trivial topology with magnetism results in novel phases of matter, such as Quantum Anomalous Hall (QAH) or axion insulator phases. Even more exotic states with high and tunable Chern numbers are expected at the contact of…

We present the model of a quantum dot (QD) consisting of a spherical core-bulk heterostructure made of 3D topological insulator (TI) materials, such as PbTe/Pb$_{0.31}$Sn$_{0.69}$Te, with bound massless and helical Weyl states existing at…

Mesoscale and Nanoscale Physics · Physics 2013-09-12 Hari P. Paudel , Michael N. Leuenberger

Topological insulators in three dimensions are nonmagnetic insulators that possess metallic surface states as a consequence of the nontrivial topology of electronic wavefunctions in the bulk of the material. They are the first known…

Strongly Correlated Electrons · Physics 2012-01-26 M. Zahid Hasan , Joel E. Moore

High-order topological insulators are a recent development extending the topological theory of charge polarization to higher multipole moments. Since their theoretical proposal, several experimental realizations of high-order topological…

Mesoscale and Nanoscale Physics · Physics 2019-01-23 Marc Serra-Garcia , Roman Süsstrunk , Sebastian D. Huber

Periodically-driven or Floquet systems can realize anomalous topological phenomena that do not exist in any equilibrium states of matter, whose classification and characterization require new theoretical ideas that are beyond the…

Mesoscale and Nanoscale Physics · Physics 2020-10-27 Rui-Xing Zhang , Zhi-Cheng Yang

We propose a realization of a two-dimensional higher-order topological insulator with ultracold atoms loaded into orbital angular momentum (OAM) states of an optical lattice. The symmetries of the OAM states induce relative phases in the…

Quantum Gases · Physics 2019-11-11 G. Pelegrí , A. M. Marques , V. Ahufinger , J. Mompart , R. G. Dias

In recent years, higher-order topological phases have attracted great interest in various fields of physics. These phases have protected boundary states at lower-dimensional boundaries than the conventional first-order topological phases…

Mesoscale and Nanoscale Physics · Physics 2024-04-19 Yan-Bin Yang , Jiong-Hao Wang , Kai Li , Yong Xu