Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session S52: Photonic Topological MaterialsFocus
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Sponsoring Units: DAMOP Chair: Xiaopeng Li, Joint Quantum Institute, University of Maryland Room: Hilton Baltimore Holiday Ballroom 3 |
Thursday, March 17, 2016 11:15AM - 11:51AM |
S52.00001: The Science and Applications of Photonic Topological Insulators: From Robust Delay Lines to Non-Reciprocal Metawaveguides Invited Speaker: Gennady Shvets Electromagnetic (EM) waves propagating through an inhomogeneous medium inevitably scatter whenever the medium’s electromagnetic properties change on the scale of a single wavelength. This fundamental phenomenon constrains how optical structures are designed and interfaced with each other. Our theoretical work indicates [1] that electromagnetic structures collectively known as photonic topological insulators (PTIs) can be employed to overcome this fundamental limitation, thereby paving the way to ultra-compact photonic structures that no longer have to be wavelength-scale smooth. Here I present the first experimental demonstration of a photonic structure that supports topologically protected surface electromagnetic waves (TPSWs) that are counterparts to the edge states between two quantum spin-Hall topological insulators in condensed matter. Unlike conventional guided EM waves that do not benefit from topological protection, TPSWs are shown to experience reflections-free time delays when detoured around sharply-curved paths, thus offering a unique paradigm for wave buffers and delay lines. I will also discuss how the photonic analogs of the quantum Hall and valley-Hall topological insulators can be realized and interfaced with each other. [1] T. Ma et. al., "Guiding Electromagnetic Waves around Sharp Corners: Topologically Protected Photonic Transport in Metawaveguides", Phys. Rev. Lett. 114, 127401 (2015). [Preview Abstract] |
Thursday, March 17, 2016 11:51AM - 12:03PM |
S52.00002: Disordered Interactions and Fractional Quantum Hall States Wade DeGottardi, Mohammad Hafezi The possibility that topological ordered states may be realized in photonic systems has recently attracted a great deal of attention. Given the rich phenomenology of the fractional quantum Hall effect, the bosonic Laughlin states have been of particular focus in this context. These states are known to arise in strongly nonlinear photonic lattices with artificial gauge fields, where nonlinearities associated with the resonators mimic on-site interactions. These effective interaction strengths are not universal and are subject to spatial disorder. We present a detailed study of the stability of these states and what implications they have for experiments. [Preview Abstract] |
Thursday, March 17, 2016 12:03PM - 12:15PM |
S52.00003: Topological photonic crystal with ideal Weyl points Luyang Wang, Shao-Kai Jian, Hong Yao Weyl points in three-dimensional photonic crystals behave as monopoles of Berry flux in momentum space. Here, based on symmetry analysis, we show that a minimal number of symmetry-related Weyl points can be realized in time-reversal invariant photonic crystals. We propose to realize these ``ideal'' Weyl points in modified double-gyroid photonic crystals, which is confirmed by our first-principle photonic band-structure calculations. Photonic crystals with ideal Weyl points are qualitatively advantageous in applications such as angular and frequency selectivity, broadband invisibility cloaking, and broadband 3D-imaging. [Preview Abstract] |
Thursday, March 17, 2016 12:15PM - 12:27PM |
S52.00004: Topological photonics: an observation of Landau levels for optical photons Nathan Schine, Albert Ryou, Ariel Sommer, Jonathan Simon Creating photonic materials with nontrivial topological characteristics has seen burgeoning interest in recent years; however, a major route to topology, a magnetic field for continuum photons, has remained elusive. We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We will discuss the conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids. [Preview Abstract] |
Thursday, March 17, 2016 12:27PM - 12:39PM |
S52.00005: Topological crystalline insulators in photonic systems Jianxiao Zhang, Mikael Rechtsman, Chao-Xing Liu Topological crystalline insulators are a class of materials with a bulk energy gap and edge or surface modes, which are protected by crystalline symmetry, at their boundaries. They have been realized in electronic systems: in particular, in SnTe. In this work, we propose a mechanism to realize photonic boundary states topologically protected by crystalline symmetry. We map this one-dimensional system to a two-dimensional lattice model with opposite magnetic fields, as well as opposite Chern numbers, in its even and odd mirror parity subspaces, thus corresponding to a topological mirror insulator. Furthermore, we test how sensitive and robust edge modes depend on their mirror parity by performing time dependent evolution simulation of edge modes in a photonic setting with realistic experimental parameters. [Preview Abstract] |
Thursday, March 17, 2016 12:39PM - 12:51PM |
S52.00006: Braiding light quanta Thomas Iadecola, Thomas Schuster, Claudio Chamon The possibility that anyons — quantum particles other than fermions or bosons — can emerge in condensed matter systems has motivated generations of physicists. In addition to being of fundamental scientific importance, so-called non-Abelian anyons are particularly sought-after for potential applications to quantum computing. However, experimental evidence of anyons in electronic systems remains inconclusive. We propose to demonstrate non-Abelian braiding by injecting coherent states of light into “topological guided modes” in specially-fabricated photonic waveguide arrays. These modes are photonic analogues of topological zero modes in electronic systems. Light traveling inside spatially well-separated topological guided modes can be braided, leading to the accumulation of non-Abelian phases. We propose an optical interference experiment to probe this non-Abelian braiding directly. [Preview Abstract] |
Thursday, March 17, 2016 12:51PM - 1:03PM |
S52.00007: Topological Photonics for Continuous Media Mario Silveirinha Photonic crystals have revolutionized light-based technologies during the last three decades. Notably, it was recently discovered that the light propagation in photonic crystals may depend on some topological characteristics determined by the manner how the light states are mutually entangled. The usual topological classification of photonic crystals explores the fact that these structures are periodic. The periodicity is essential to ensure that the underlying wave vector space is a closed surface with no boundary. In this talk, we prove that it is possible calculate Chern invariants for a wide class of continuous bianisotropic electromagnetic media with no intrinsic periodicity. The nontrivial topology of the relevant continuous materials is linked with the emergence of edge states. Moreover, we will demonstrate that continuous photonic media with the time-reversal symmetry can be topologically characterized by a Z$_{\mathrm{2}}$ integer. This novel classification extends for the first time the theory of electronic topological insulators to a wide range of photonic platforms, and is expected to have an impact in the design of novel photonic systems that enable a topologically protected transport of optical energy. [Preview Abstract] |
Thursday, March 17, 2016 1:03PM - 1:15PM |
S52.00008: From Casimir-Polder Force to Dicke Physics: Interaction between Atoms and a Topological Insulator Sebastian Fuchs, Stefan Buhmann We apply the theory of macroscopic quantum electrodynamics in dispersing and absorbing media to study the Casimir-Polder force between an atom and a topological insulator [1]. The electromagnetic response of a topological insulator surface leads to a mixing of electric and magnetic fields, breaking the time-reversal symmetry [2, 3]. The coupling of these fields to an atom causes shifts of the atom's eigenenergies and modified decay rates near the surface of the topological insulator. Energy shifts and modified decay rates cannot only be triggered by the presence of a material, but can be caused by other atoms in close proximity as well. The collective dynamics of atoms (Dicke Physics) leads to a superradiant burst [4]. Combining macroscopic QED and Dicke physics opens the door to the investigation of cooperative atom-surface interactions. [1] S. Y. Buhmann, Dispersion Forces II, Springer-Verlag Berlin Heidelberg (2012). [2] S. Y. Buhmann, D. T. Butcher, and S. Scheel, New Journal of Physics 14, 083034 (2012). [3] J. A. Crosse, S. Fuchs, and S. Y. Buhmann, arXiv: 1509.03012 (2015). [4] S. Fuchs, J. Ankerhold, M. Blencowe, and B. Kubala, arXiv: 1501.07841 (2015). [Preview Abstract] |
Thursday, March 17, 2016 1:15PM - 1:27PM |
S52.00009: Robust topological states in Parity-time (PT) symmetric photonic lattices Andrew Harter, Yogesh Joglekar We consider generalized Aubry-Andre models, which support topological states and are experimentally realizable in integrated waveguide lattices, in the presence of balanced gain and loss. When the gain-loss strength exceeds a threshold set by the nearest neighbor tunneling, the non-Hermitian, PT-symmetric Hamiltonian of this system undergoes PT breaking transition. We investigate the interplay between the PT-breaking transition, tuned by the gain-loss strength, and topological transitions between different states with Chern numbers. We show, due to sub-lattice-localization property of the topological edge states in these models, these edge states remain robust across the PT-breaking transition. We present the consequences of this result for light-propagation in such materials, obtained via both tight-binding model and beam-propagation method. [Preview Abstract] |
Thursday, March 17, 2016 1:27PM - 1:39PM |
S52.00010: Exciting Reflectionless, Unidirectional Edge Mode in Bianisotropic Meta-waveguide Using Rotating Dipole Antenna. Bo Xiao, Thomas Antonsen, Edward Ott, Steven Anlage, Tzuhsuan Ma, Gennady Shvets Electronic chiral edge states in Quantum Hall Effect systems has attracted a lot of attention in recent years because of its unique directionality and robustness against scattering from disorder. Its electromagnetic counterpart can be found in photonic crystals, which is a material with periodic dielectric constant. Here we present the experimental results demonstrating the unidirectional edge mode inside a bi-anisotropic meta-waveguide [1] (BMW) structure. It is a parallel plate waveguide with metal rods placed in a hexagonal lattice. Half of the rods are attached to the top plate while the other half are attached to the bottom plate creating a domain wall. The edge mode is excited by two loop antennas placed perpendicular to each other within one wavelength, generating a rotating magnetic dipole that couples to the left or right-going mode. The transmission measurement are taken along the BMW boundary and shows high transmission only around the edge, thus confirming the presence of an edge mode. We also demonstrated that very high directivity can be achieved when the input amplitude and phase of the two loop antennas are tuned properly. [1] T. Ma, A. B. Khanikaev, S. H. Mousavi, And G. Shvets, Phys. Rev. Lett. 114, 127401 (2015). [Preview Abstract] |
Thursday, March 17, 2016 1:39PM - 1:51PM |
S52.00011: Angle-Resolved Mid-Infrared Spectroscopy of Gyroid Photonic Crystals Emil T. Khabiboulline, Siying Peng, Philip Hon, Runyu Zhang, Hongjie Chen, Luke A. Sweatlock, Paul Braun, Harry A. Atwater Photonic topological insulators form a new class of materials with exciting properties. Theory has indicated that gyroid photonic crystals are photonic topological insulators. In this paper, we experimentally characterize the photonic properties of gyroid photonic crystals at mid-infrared wavelengths, using angle-resolved spectroscopy with coherent light from a quantum cascade laser tuned from 7.7 $\mu$m to 11.1 $\mu$m and focused onto a 100 $\mu$m $\times$ 100 $\mu$m spot. From measurements of reflection and transmission spectra over incidence angles, we construct the band structure of the photonic crystals. In this study, the photonic crystals are single and double gyroid made of amorphous silicon, with unit cell size of 5 $\mu$m, sitting on an intrinsic silicon substrate. Simulations predict band gaps for the single gyroid and Weyl points for the double gyroid. We compare results of angle-resolved spectroscopy experiments with simulations for nanofabricated gyroid structures and discuss the topological features observable in angle-resolved scattering. [Preview Abstract] |
Thursday, March 17, 2016 1:51PM - 2:03PM |
S52.00012: Squeezing as a route to photonic analogues of topological superconductors Martin Houde, Vittorio Peano, Christian Brendel, Florian Marquardt, Aashish Clerk There has been considerable recent interest in studying topological phases of photonic systems. In many cases the resulting system is described by a quadratic particle-conserving Hamiltonian which is directly equivalent to its fermionic counterpart. Here, we consider a class of photonic topological phases where this correspondence fails: photonic systems where particle-number non-conserving terms break time-reversal symmetry [1]. We show that these phases support protected edge modes which facilitate chiral inelastic and elastic transport channels. We also discuss the possibility of quantum amplification using these edge states. Our system could be realized in a variety of systems, including nonlinear photonic crystals, superconducting circuits and optomechanical systems.\\ \\ [0pt] [1] Vittorio Peano, Martin Houde, Christian Brendel, Florian Marquardt, and Aashish Clerk, arXiv:1508.01383 (2015). [Preview Abstract] |
Thursday, March 17, 2016 2:03PM - 2:15PM |
S52.00013: \textbf{Gyroid photonic crystal with Weyl points: synthesis and mid-infrared photonic characterization} Siying Peng, Emil Khabiboulline, Runyu Zhang, Hongjie Chen, Philip Hon, Luke Sweatlock, Paul Braun, Harry Atwater Weyl points are degenerate energy states resulting from crossings of linear bands in 3D momentum space. Unlike their 2D counterparts, Weyl points are bulk degenerate states that are stable to weak perturbation. The topological surface states associated with Weyl points exhibit unidirectional backscattering-immune transport. Double gyroid photonic crystals with a parity-breaking perturbation are predicted to possess Weyl points. We designed and synthesized single and double gyroid mid-IR photonic crystals composed of a-Si. We characterized them by mid-IR spectroscopy. We observed 100{\%} reflection at 8$\mu $m for single gyroids with unit cell size of 5$\mu $m, in agreement with the predicted photonic bandgap seen in full-wave EM simulations. As the unit cell size of single gyroids changes to 6$\mu $m, the observed reflection peak shifted to 9$\mu $m, also agreeing with simulation. For double gyroids with unit cell size of 5$\mu $m, we observed a 20{\%} decrease in reflection at 8$\mu $m, which could be explained by a new pair of states appearing within the bandgap from our simulation of double gyroids. We use angle-resolved mid-IR spectroscopy with a QCL to characterize Weyl points. [Preview Abstract] |
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