Yuri S. Kivshar

Bio: Yuri S. Kivshar is an academic researcher from Australian National University. The author has contributed to research in topics: Metamaterial & Soliton. The author has an hindex of 126, co-authored 1845 publications receiving 79415 citations. Previous affiliations of Yuri S. Kivshar include Technische Universität Darmstadt & Los Alamos National Laboratory.

Topological Polarization Singularities in Metaphotonics

Abstract: Polarization singularities of vectorial electromagnetic fields locate at the positions (such as points, lines, or surfaces) where properties of polarization ellipses are not defined. They are manifested as circular and linear polarization, for which respectively the semi-major axes and normal vectors of polarization ellipses become indefinite. First observed in conical diffraction in the 1830s, the field of polarization singularities has been systematically reshaped and deepened by many pioneers of wave optics. Together with other exotic phenomena such as non-Hermiticity and topology, polarization singularities have been introduced into the vibrant field of nanophotonics, rendering unprecedented flexibilities for manipulations of light-matter interactions at the nanoscale. Here we review the recent results on the generation and observation of polarization singularities in metaphotonics. We start with the discussion of polarization singularities in the Mie theory, where both electric and magnetic multipoles are explored from perspectives of local and global polarization properties. We then proceed with the discussion of various photonic-crystal structures, for which both near- and far-field patterns manifest diverse polarization singularities characterized by the integer Poincare or more general half-integer Hopf indices (topological charges). Next, we review the most recent studies of conversions from polarization to phase singularities in scalar wave optics, demonstrating how bound states in the continuum can be exploited to generate directly optical vortices of various charges. Throughout our paper, we discuss and highlight several fundamental concepts and demonstrate their close connections and special links to metaphotonics. We believe polarization singularities can provide novel perspectives for light-matter manipulation for both fundamental studies and their practical applications.

Mapping phases of singular scalar light fields

Abstract: We implement experimentally a simple method for accurate measurements of phase distributions of scalar light fields. The method is based on the polarimetric technique for recording the polarization maps of vector fields, where coaxial superposition of orthogonally polarized reference and signal beams allows the signal phase to be reconstructed from the polarization map of the total field. We demonstrate this method by resolving topologically neutral pairs of closely positioned vortices in a speckle field and recovering the positions of vortices within a Laguerre-Gaussian beam with the topological charge three.

Plasmonic Bloch oscillations in chirped metal-dielectric structures

Abstract: We study the propagation of plasmon polaritons in one-dimensional chirped metal-dielectric layered structures We find an optical Wannier‐Stark ladder in the mode spectrum and analyze Bloch oscillations associated with the coupling of surface plasmons localized at the metal-dielectric interfaces For long structures, we find that the energy flow may dramatically change its direction, thus providing possibilities for the beam steering in the transmission band © 2009 American Institute of Physics DOI: 101063/13119666 Recent technological advances opened up many opportunities for nanofabrication allowing one to study the fundamental effects earlier predicted only theoretically As an example, electronic Bloch oscillations predicted in 1928 Ref 1 were observed almost 50 years later, 2 when semiconductor superlattices with nanometer-scale thick layers were manufactured Nowadays, one of the most intriguing directions of research is associated with plasmon-polariton excitations and light manipulation at nanoscales 3,4 in various metal-dielectric structures, including multilayered periodic metal film stacks Periodic metal-dielectric stacks have been studied in a number of papers 5‐7 The studies of the transmission properties 6,7 revealed that such structures may exhibit resonant transmission due to plasmon tunneling through the structure This effect by itself is quite remarkable, since every second layer in the structure is made of metal, ie, it is opaque It was suggested that these structures can be used as spatial filters 7 Optical Bloch oscillations in periodic dielectric structures represent an analog of the electronic Bloch oscillations in crystals Such oscillations were observed in different dielectric structures, 8‐11 and they were also predicted to occur in metal-dielectric structures 12,13 where it was shown that the structures with spatially modulated refractive index of dielectric layers can exhibit optical Bloch oscillations 12 More complex heterostructures containing coupled dielectric cavities sandwiched between the metal-dielectric waveguides were also shown to exhibit Bloch oscillations, 13 somewhat similar to those observed in dielectric superlattices 11 In this letter we study the beam propagation in structures with linearly varying chirped thickness of the dielectric layers and uniform thickness of metallic layers We predict the possibility of plasmonic Bloch oscillations arising due to the excitation and coupling of plasmon polaritons We show that the energy flow can change its direction within one period of oscillations, leading to the beam curling similar to that predicted for layered structures with left-handed metamaterials 14 Such flexibility of beam control can open up opportunities of the light manipulation on nanoscales We start our analysis by studying periodic onedimensional stack consisting of thin metal layers of the width h separated by layers of conventional dielectric of the width l, so that the period of the structure is defined as =h+l The refractive index in one unit-cell of the structure is written as

Magneto-optical response enhanced by Mie resonances in nanoantennas

Abstract: Control of light by an external magnetic field is one of the important methods for modulation of its intensity and polarisation. Magneto-optical effects at the nanoscale are usually observed in magnetophotonic crystals, nanostructured hybrid materials or magnetoplasmonic crystals. An indirect action of an external magnetic field (e.g. through the Faraday effect) is explained by the fact that natural materials exhibit negligible magnetism at optical frequencies. However, the concept of metamaterials overcome this limitation imposed by nature by designing artificial subwavelength meta-atoms that support a strong magnetic response, usually termed as optical magnetism, even when they are made of nonmagnetic materials. The fundamental question is what would be the effect of the interaction between an external magnetic field and an optically-induced magnetic response of metamaterial structures. Here we make the first step toward answering this fundamental question and demonstrate the multifold enhancement of the magneto-optical response of nanoantenna lattices due to the optical magnetism.

Existence and Stability of Coupled Atomic-molecular Bose-Einstein Condensates

Abstract: We analyze a mean-field model of an atomic Bose-Einstein condensate parametrically coupled to a molecular condensate via a Raman photoassociation process. We show that an interplay of nonlinear interspecies and intraspecies interactions leads to the formation of mutually trapped states of a hybrid condensate, which are spatially localized and dynamically stable even without a trap.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。