Photonic Floquet topological insulators
Mikael C. Rechtsman,Julia M. Zeuner,Yonatan Plotnik,Yaakov Lumer,Daniel K. Podolsky,Felix Dreisow,Stefan Nolte,Mordechai Segev,Alexander Szameit +8 more
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TLDR
This work proposes and experimentally demonstrate a photonic topological insulator free of external fields and with scatter-free edge transport—a photonic lattice exhibiting topologically protected transport of visible light on the lattice edges.Abstract:
Topological insulators are a new phase of matter, with the striking property that conduction of electrons occurs only on their surfaces. In two dimensions, electrons on the surface of a topological insulator are not scattered despite defects and disorder, providing robustness akin to that of superconductors. Topological insulators are predicted to have wide-ranging applications in fault-tolerant quantum computing and spintronics. Substantial effort has been directed towards realizing topological insulators for electromagnetic waves. One-dimensional systems with topological edge states have been demonstrated, but these states are zero-dimensional and therefore exhibit no transport properties. Topological protection of microwaves has been observed using a mechanism similar to the quantum Hall effect, by placing a gyromagnetic photonic crystal in an external magnetic field. But because magnetic effects are very weak at optical frequencies, realizing photonic topological insulators with scatter-free edge states requires a fundamentally different mechanism-one that is free of magnetic fields. A number of proposals for photonic topological transport have been put forward recently. One suggested temporal modulation of a photonic crystal, thus breaking time-reversal symmetry and inducing one-way edge states. This is in the spirit of the proposed Floquet topological insulators, in which temporal variations in solid-state systems induce topological edge states. Here we propose and experimentally demonstrate a photonic topological insulator free of external fields and with scatter-free edge transport-a photonic lattice exhibiting topologically protected transport of visible light on the lattice edges. Our system is composed of an array of evanescently coupled helical waveguides arranged in a graphene-like honeycomb lattice. Paraxial diffraction of light is described by a Schrodinger equation where the propagation coordinate (z) acts as 'time'. Thus the helicity of the waveguides breaks z-reversal symmetry as proposed for Floquet topological insulators. This structure results in one-way edge states that are topologically protected from scattering.read more
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Photonic topological insulator in synthetic dimensions
Eran Lustig,Steffen Weimann,Yonatan Plotnik,Yaakov Lumer,Miguel A. Bandres,Alexander Szameit,Mordechai Segev +6 more
TL;DR: In this article, a photonic topological insulator in synthetic dimensions has been proposed, in which photons are subjected to an effective magnetic field in a space with one spatial dimension and one synthetic modal dimension.
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Measurement of topological invariants in a 2D photonic system
TL;DR: In this paper, a photonic analogue of charge pumping in electronic quantum Hall systems is demonstrated by using a finite 2D square annulus of ring resonators, and it is shown that the edge spectrum resonances shift by the winding number.
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Analogue computing with metamaterials
TL;DR: This Review surveys the basic principles, recent advances and promising future directions for wave-based-metamaterial analogue computing systems, and describes some of the most exciting applications suggested for these Computing metamaterials, including image processing, edge detection, equation solving and machine learning.
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Two-Dimensionally Confined Topological Edge States in Photonic Crystals
TL;DR: In this article, an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states is presented, and three dimensional finite-difference time-domain calculations show these edges to be confined in the out-ofplane direction by total internal reflection.
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Anomalous helical edge states in a non-Hermitian Chern insulator
TL;DR: In this article, a non-Hermitian extension of a Chern insulator and its bulk-boundary correspondence are investigated, and it is shown that in addition to the robust chiral edge states that reflect the nontrivial topology of the bulk (nonzero Chern number), anomalous helical edge states localized only at one edge can appear.
References
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