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magnetism for light

“ It is well to read everything of something, and something of everything. ”
- Joseph Brodsky
News and Views article by Prof. Khanikaev1 covering new advance in realization of topologically nontrivial photonic states in all-silicon platform has appeared in December issue of Nature Photonics.
    The past three decades have witnessed the discoveries of the quantum Hall effect, the quantum spin Hall effect and topological insulators, revolutionizing our view of the quantum states of matter. The associated exotic states of matter are all characterized by insulating behavior in the bulk and the presence of edge states that contribute to charge or spin currents and that persist even when the edge is distorted or contains impurities.
    In the past few years, several research groups have realized that similar 'robust' conducting edge states can be implemented in photonic systems. A few recent studies have suggested that emulating the effect of the magnetic field in photonics offers the same rich physics of topologically protected systems. One of the approaches to topologically protected photonics relaying on a special class of metamaterials called “photonic meta-crystals” was demonstrated by Prof. Khanikaev and co-workers and was reported in Nature Materials earlier this year2.

Artistic depiction of topologically protected photonic edge transport in an array of silicon resonators (After Ref. 1).
    In his current New and Views article Prof. Khanikaev reviews the work by M. Hafezi et al. published in Nature Photonics3 and presenting the first proof-of-concept experimental demonstration that a synthetic magnetic field engineered in an array of silicon ring resonators results in a topologically nontrivial state of light and robust photonic edge transport. The experimentally observed topologically protected photonic edge transport in a silicon chip paves the way to realizing unprecedented control of light using synthetic magnetic fields and opens up new avenues for optical information processing.
1. A. B. Khanikaev, “Optical physics: On-chip synthetic magnetic field”, Nature Photonics 7, 941–943 (2013).
2. A. B. Khanikaev, S. H. Mousavi, W.-K. Tse, M. Kargarian, A. H. MacDonald, G. Shvets, “Photonic Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials”, Nature Materials 12, 233–239 (2013).
3. M. Hafezi, S. Mittal, J. Fan, A. Migdall, J. M. Taylor, “Imaging topological edge states in silicon photonics”, Nature Photonics 7, 1001–1005 (2013).