scholarly journals Transport properties of Floquet topological superconductors at the transition from the topological phase to the Anderson localized phase

2014 ◽  
Vol 90 (15) ◽  
Author(s):  
Pei Wang ◽  
Qing-feng Sun ◽  
X. C. Xie
Keyword(s):  
Transport Properties ◽  
Topological Phase ◽  
Topological Superconductors

scholarly journals Observation of non-Hermitian topology and its bulk–edge correspondence in an active mechanical metamaterial

2020 ◽  
Vol 117 (47) ◽  
pp. 29561-29568 ◽  
Author(s):  
Ananya Ghatak ◽  
Martin Brandenbourger ◽  
Jasper van Wezel ◽  
Corentin Coulais
Keyword(s):  
Transport Properties ◽  
Cold Atoms ◽  
Topological Invariant ◽  
Geophysical Flows ◽  
Topological Phases ◽  
Topological Phase ◽  
Edge Mode ◽  
Mode Localization ◽  
Open Questions ◽  
Wide Range

Topological edge modes are excitations that are localized at the materials’ edges and yet are characterized by a topological invariant defined in the bulk. Such bulk–edge correspondence has enabled the creation of robust electronic, electromagnetic, and mechanical transport properties across a wide range of systems, from cold atoms to metamaterials, active matter, and geophysical flows. Recently, the advent of non-Hermitian topological systems—wherein energy is not conserved—has sparked considerable theoretical advances. In particular, novel topological phases that can only exist in non-Hermitian systems have been introduced. However, whether such phases can be experimentally observed, and what their properties are, have remained open questions. Here, we identify and observe a form of bulk–edge correspondence for a particular non-Hermitian topological phase. We find that a change in the bulk non-Hermitian topological invariant leads to a change of topological edge-mode localization together with peculiar purely non-Hermitian properties. Using a quantum-to-classical analogy, we create a mechanical metamaterial with nonreciprocal interactions, in which we observe experimentally the predicted bulk–edge correspondence, demonstrating its robustness. Our results open avenues for the field of non-Hermitian topology and for manipulating waves in unprecedented fashions.

scholarly journals Topological Edge States of a Majorana BBH Model

2021 ◽  
Vol 6 (2) ◽  
pp. 15
Author(s):  
Alfonso Maiellaro ◽  
Roberta Citro
Keyword(s):  
2D Materials ◽  
Finite Size ◽  
Majorana Fermions ◽  
Topological Phase ◽  
Two Dimensional ◽  
Edge States ◽  
Finite Size Scaling ◽  
Topological Properties ◽  
Berry Curvature ◽  
Topological Superconductors

We investigate a Majorana Benalcazar–Bernevig–Hughes (BBH) model showing the emergence of topological corner states. The model, consisting of a two-dimensional Su–Schrieffer–Heeger (SSH) system of Majorana fermions with π flux, exhibits a non-trivial topological phase in the absence of Berry curvature, while the Berry connection leads to a non-trivial topology. Indeed, the system belongs to the class of second-order topological superconductors (HOTSC2), exhibiting corner Majorana states protected by C4 symmetry and reflection symmetries. By calculating the 2D Zak phase, we derive the topological phase diagram of the system and demonstrate the bulk-edge correspondence. Finally, we analyze the finite size scaling behavior of the topological properties. Our results can serve to design new 2D materials with non-zero Zak phase and robust edge states.

Stark and Zeeman effects on the topological phase and transport properties of topological crystalline insulator thin films

2020 ◽  
Vol 22 (21) ◽  
pp. 12129-12139
Author(s):  
Pham Thi Huong ◽  
Chuong V. Nguyen ◽  
Huynh V. Phuc ◽  
Nguyen N. Hieu ◽  
Bui D. Hoi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Thin Films ◽  
Phase Transition ◽  
Electric Field ◽  
Transport Properties ◽  
Group Velocity ◽  
Dirac Fermions ◽  
Topological Phase ◽  
Topological Crystalline Insulator

We applied a perpendicular electric field and an in-plane magnetic field to not only tune the Dirac gap of a SnTe(001) thin film and find the phase transition but also to investigate their effects on the group velocity of both massless and massive surface Dirac fermions.

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