Symmetry-protected topological photonic crystal in three dimensions

By Ling Lu, Chen Fang, Liang Fu, Steven G. Johnson, John D. Joannopoulos, Marin Soljačić. Nature Physics, 2015

282 citations recorded by the source corpus.

Crystal symmetries may protect single Dirac cones on the surface of a photonic crystal, creating a photonic analogue of a three-dimensional solid-state topological insulator. Topology of electron wavefunctions was first introduced to characterize the quantum Hall states in two dimensions discovered in 1980 (ref. 1). Over the past decade, it has been recognized that symmetry plays a crucial role in the classification of topological phases, leading to the broad notion of symmetry-protected topological phases2. As a primary example, topological insulators3,4 are distinguished from normal insulators in the presence of time-reversal symmetry (). A three-dimensional (3D) topological insulator3,4,5,6 exhibits an odd number of protected surface Dirac cones, a unique property that cannot be realized in any 2D systems. Importantly, the existence of topological insulators requires Kramers’ degeneracy in spin–orbit coupled electronic materials; this forbids any direct analogue in boson systems7. In this report, we discover a 3D topological photonic crystal phase hosting a single surface Dirac cone, which is protected by a crystal symmetry8,9,10—the nonsymmorphic glide reflection11,12,13 rather than . Such a gapless surface state is fully robust against random disorder of any type14,15. This bosonic topological band structure is achieved by applying alternating magnetization to gap out the 3D ‘generalized Dirac points’ discovered in the bulk of our crystal. The Z2 bulk invariant is characterized through the evolution of Wannier centres16. Our proposal—readily realizable using ferrimagnetic materials at microwave frequencies17,18—expands the scope of 3D topological materials from fermions to bosons.

Subfields: Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/b7de72bdffb2e026ba770c64e28202c13be8d741

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Citations in the corpus

Three-dimensional all-dielectric photonic topological insulator (2016, methodology): “in magnetic-photonic crystals emulating Quantum Hall effect (QHE) which were successfully realized in 2D [ 9, 25] and has also been recently extended theoretically to three dimensions [ 26], or temporal modulation emulating the effect of external magnetic field [ 27, 28, 29, 17, 30, 13].”
Experimental realization of a Weyl exceptional ring (2018, background): “[25] Ling Lu, Chen Fang, Liang Fu, Steven G.”
Experimental discovery of nodal chains (2017, background): “[31] Ling Lu, Chen Fang, Liang Fu, Steven G Johnson, John D Joannopoulos, and Marin Soljačić, “Symmetryprotected topological photonic crystal in three dimensions,” Nature Physics 12, 337–340 (2016).”
Topological photonics (2018, methodology): “Experiments along these lines have been performed with cold atoms by H.-I. Lu et al. (2016) and in photonics by Wimmer et al. (2017).”
Roadmap on topological photonics (2022, unknown): “Following the early proposal by Haldane and Raghu [6], the conceptually most direct implementations rely on magneto-optical effects utilizing gyrotropic materials [7], or exploit the polarization degree in media that exhibit circular birefringence [8] or bianisotropy [9].”