scholarly journals Experimental realization of a nonlinear acoustic lens with a tunable focus

2014 ◽  
Vol 104 (1) ◽  
pp. 014103 ◽  
Author(s):  
Carly M. Donahue ◽  
Paul W. J. Anzel ◽  
Luca Bonanomi ◽  
Thomas A. Keller ◽  
Chiara Daraio
Keyword(s):  
Experimental Realization ◽  
Acoustic Lens ◽  
Nonlinear Acoustic

Phononic-Crystal Acoustic Lens by Design for Energy-Transmission Devices

2012 ◽  
Vol 132 (5) ◽  
pp. 686-690
Author(s):  
Yusuke Kanno ◽  
Kenji Tsuruta ◽  
Kazuhiro Fujimori ◽  
Hideki Fukano ◽  
Shigeji Nogi
Keyword(s):  
Phononic Crystal ◽  
Energy Transmission ◽  
Acoustic Lens

scholarly journals Non-Abelian generalizations of the Hofstadter model: spin–orbit-coupled butterfly pairs

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Yi Yang ◽  
Bo Zhen ◽  
John D. Joannopoulos ◽  
Marin Soljačić
Keyword(s):  
Quantum Hall ◽  
Building Blocks ◽  
Real Space ◽  
Gauge Fields ◽  
Spin Orbit ◽  
Abelian Gauge ◽  
Experimental Realization ◽  
Integer Quantum Hall Effect ◽  
Integer Quantum ◽  
Necessary And Sufficient

Abstract The Hofstadter model, well known for its fractal butterfly spectrum, describes two-dimensional electrons under a perpendicular magnetic field, which gives rise to the integer quantum Hall effect. Inspired by the real-space building blocks of non-Abelian gauge fields from a recent experiment, we introduce and theoretically study two non-Abelian generalizations of the Hofstadter model. Each model describes two pairs of Hofstadter butterflies that are spin–orbit coupled. In contrast to the original Hofstadter model that can be equivalently studied in the Landau and symmetric gauges, the corresponding non-Abelian generalizations exhibit distinct spectra due to the non-commutativity of the gauge fields. We derive the genuine (necessary and sufficient) non-Abelian condition for the two models from the commutativity of their arbitrary loop operators. At zero energy, the models are gapless and host Weyl and Dirac points protected by internal and crystalline symmetries. Double (8-fold), triple (12-fold), and quadrupole (16-fold) Dirac points also emerge, especially under equal hopping phases of the non-Abelian potentials. At other fillings, the gapped phases of the models give rise to topological insulators. We conclude by discussing possible schemes for experimental realization of the models on photonic platforms.

Experimental realization of atomically flat and AlO2 -terminated LaAlO3 (001) substrate surfaces

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
Jeong Rae Kim ◽  
Jiyeon N. Lee ◽  
Junsik Mun ◽  
Yoonkoo Kim ◽  
Yeong Jae Shin ◽  
...  
Keyword(s):  
Experimental Realization ◽  
Substrate Surfaces ◽  
Atomically Flat

scholarly journals Non-Hermitian route to higher-order topology in an acoustic crystal

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
He Gao ◽  
Haoran Xue ◽  
Zhongming Gu ◽  
Tuo Liu ◽  
Jie Zhu ◽  
...  
Keyword(s):  
Higher Order ◽  
Order Topology ◽  
Topological Phases ◽  
Edge States ◽  
Experimental Realization ◽  
Artificial Materials ◽  
Intrinsic Loss ◽  
Topological Phases Of Matter ◽  
Hierarchical Features ◽  
Nontrivial Topology

AbstractTopological phases of matter are classified based on their Hermitian Hamiltonians, whose real-valued dispersions together with orthogonal eigenstates form nontrivial topology. In the recently discovered higher-order topological insulators (TIs), the bulk topology can even exhibit hierarchical features, leading to topological corner states, as demonstrated in many photonic and acoustic artificial materials. Naturally, the intrinsic loss in these artificial materials has been omitted in the topology definition, due to its non-Hermitian nature; in practice, the presence of loss is generally considered harmful to the topological corner states. Here, we report the experimental realization of a higher-order TI in an acoustic crystal, whose nontrivial topology is induced by deliberately introduced losses. With local acoustic measurements, we identify a topological bulk bandgap that is populated with gapped edge states and in-gap corner states, as the hallmark signatures of hierarchical higher-order topology. Our work establishes the non-Hermitian route to higher-order topology, and paves the way to exploring various exotic non-Hermiticity-induced topological phases.

scholarly journals Experimental realization of the classical Dicke model

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
Mario A. Quiroz-Juárez ◽  
Jorge Chávez-Carlos ◽  
José L. Aragón ◽  
Jorge G. Hirsch ◽  
Roberto de J. León-Montiel
Keyword(s):  
Experimental Realization ◽  
Dicke Model
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