topological photonics

topological photonics
Name	Topological photonics
Field	Photonics, Condensed matter physics
Subdiscipline	Optics, Quantum optics

Contents

topological photonics is an interdisciplinary field exploring robust light-matter phenomena that derive from topological properties of band structures, drawing concepts from Paul Dirac, David Thouless, Frank Wilczek and linking experimental platforms across institutions such as M.I.T., Harvard University, University of California, Berkeley and Caltech. It synthesizes ideas from condensed matter physics and optics embodied in work by researchers at University of Oxford, École Normale Supérieure, Princeton University and University of Toronto, and informs technologies pursued by laboratories at Bell Labs, IBM Research, Intel, and NIST.

Introduction

Topological photonics originated by transferring notions developed in studies by John Bardeen, Niels Bohr, Robert Laughlin and F. Duncan M. Haldane—notably the Integer quantum Hall effect, Fractional quantum Hall effect, and the Haldane model—to electromagnetic systems, inspiring implementations in platforms developed at Stanford University and University of Pennsylvania. Early experimental demonstrations connected to theoretical proposals from groups at University of Illinois Urbana–Champaign, ETH Zurich, Max Planck Institute for the Science of Light, and Weizmann Institute of Science, making use of materials and fabrication techniques from Bell Labs, Riken, and Samsung Advanced Institute of Technology.

Topological photonics rests on mathematical structures introduced by Michael Berry (Berry phase), formalized by Shoucheng Zhang and Charles Kane with the Kane–Mele model, and expanded by Joel E. Moore to classify topological insulators; these concepts were adapted to bosonic excitations by theorists at Columbia University and University of Cambridge. Band topology descriptions employ invariants such as the Chern number from work tied to Thouless, Kohmoto, Nightingale and den Nijs and symmetry indicators related to research by Alexei Kitaev and Andrei Bernevig, with mathematical input from Michael Atiyah and Isadore Singer. Photonic analogues use Maxwell’s equations augmented by synthetic gauge fields developed in proposals by teams at Yale University, University of Chicago, and University of Maryland; models include photonic realizations of the Su–Schrieffer–Heeger model, the Harper–Hofstadter model, and the Haldane model adapted for lattice photonics by theorists influenced by Philip W. Anderson and Walter Kohn.

Photonic phases mirror electronic phases such as Quantum spin Hall effect, Chern insulator, and Topological crystalline insulator but are distinct because photons are bosons and lack a Fermi level, a perspective developed at Cornell University and University of California, Santa Barbara. Model systems include arrays inspired by Alexander Solntsev and Yuri S. Kivshar employing ring resonators akin to devices from Nokia Bell Labs; slow-light schemes trace conceptual lineage to work at University of Southampton, University of Glasgow, and Nanyang Technological University. Synthetic dimensions and Floquet engineering were proposed in papers associated with Markus Greiner, Iacopo Carusotto, and Marin Soljačić, and were experimentally pursued at University of Michigan and University of Colorado Boulder. Concepts of non-Hermitian topology developed by researchers at University of Rochester and Weizmann Institute of Science extended models to include gain and loss reminiscent of studies by Carl Bender and Nima Arkani-Hamed.

Platform diversity spans integrated photonic circuits at University of Pennsylvania and MIT Lincoln Laboratory, silicon photonics programs at Intel and University of California, Santa Barbara, microwave metamaterials at Duke University and Technion – Israel Institute of Technology, and optical waveguide arrays fabricated at Institute of Photonic Sciences and École Polytechnique Fédérale de Lausanne. Cold-atom analogues connecting to JILA and Massachusetts Institute of Technology used engineered optical lattices inspired by Wim van Saarloos and Immanuel Bloch, while exciton-polariton condensates in microcavities were advanced by groups at Paris-Saclay University and University of St Andrews. Photonic crystal implementations followed designs from Kavli Institute for Theoretical Physics, Harvard John A. Paulson School of Engineering and Applied Sciences, and Istituto Italiano di Tecnologia, and microwave circuit realizations trace to work by teams at Yale University and The Chinese University of Hong Kong.

Topologically protected waveguides and delay lines have been prototyped at Bell Labs, California Institute of Technology, and University of Toronto for robust routing relevant to photonic networks studied at Cisco Systems and Google. Devices for robust lasing exploit ideas developed at University of Pittsburgh and Monash University, while quantum light generation leveraging topology connects to experiments at University of Vienna, Max Planck Institute for Quantum Optics, and University of Cambridge. Sensor concepts informed by topological singularities were proposed by researchers at Imperial College London and University of Melbourne, and integrated circuitry efforts draw on collaborations with NTT, Samsung, and Toshiba research centers.

Key challenges under investigation at DARPA-funded programs, European Research Council projects, and initiatives at National Science Foundation include scaling to low-loss integrated platforms exemplified by work at Intel Labs and IMEC, achieving strong nonlinearities as pursued at Riken and Tokyo Institute of Technology, and integrating topological photonics with quantum technologies advanced at Quantum Information Science, Perimeter Institute for Theoretical Physics, and Los Alamos National Laboratory. Future research directions include exploiting topology for error-resilient quantum interconnects inspired by Peter Shor and Alexei Kitaev, developing active reconfigurable devices in collaboration with Siemens and Schlumberger, and cross-fertilization with emergent areas studied at Zhejiang University and Tsinghua University.