Photonic Floquet topological insulators

By M. Rechtsman, J. M. Zeuner, Y. Plotnik, Y. Lumer, D. Podolsky, F. Dreisow, S. Nolte, Mordechai Segev, Alexander Szameit. Nature, 2012

2,855 citations recorded by the source corpus.

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 Schrödinger 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.

Subfields: Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/54c67b855fa18762e122c93289b197033d6e2669

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

Optomechanical creation of magnetic fields for photons on a lattice (2015, background): “First experiments have shown such edge states [24–26].”
Experimental realization of the topological Haldane model with ultracold fermions (2014, methodology): “Using photonic crystal fibres, a classical version of this proposal was used to study topologically protected edge modes in the inversion-symmetric regime [21].”
Floquet topological transitions in a driven one-dimensional topological insulator (2015, background): “The opening of laser-induced band gaps has already been observed [18] and new experiments [19–21] and theories are being developed to unveil the states’ ﬁngerprint of their topology [8,22–25], e.g., the bulk boundary correspondence [26–28], their dynamics [29,30], occupation [31,32], transport…”
Topological insulator laser: Experiments (2018, background): “Along these lines, unidirectional topological states were observed in microwave settings (9) in the presence of a magnetic field (the electromagnetic analog of the quantum Hall effect), and, more recently, topologically protected transport phenomena have been successfully demonstrated in optical pas”
Colloquium : Topological band theory (2016, background): “(Lindner, Refael, and Galitski 2011; Kitagawa et al. 2010; Gu et al. 2011; Dóra et al. 2012; Katan and Podolsky 2013; Rechtsman et al. 2013; Kundu and Seradjeh 2013; Wang, Steinberg, et al. 2013; Wang, Wang, et al. 2014; Perez-Piskunow et al. 2014)”