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Volume 12 Issue 2, February 2013

A critical component for chip-scale integrated photonics would be a non-reciprocal optical waveguide allowing light to travel in only one direction while reflecting it in the opposite one. Inspired by concepts of parity-time-symmetric quantum theories and built on a silicon on-insulator platform using only absorptive media, a periodically modulated dielectric waveguide exhibiting unidirectional reflection has now been demonstrated, reflecting light at telecom frequencies in only one direction with a high contrast ratio.

Letter p108




  • The journal impact factor is a good predictor of the quality of journals as measured by citations to primary research articles. It is, however, a poor indicator of citations to specific papers or of the future performance of individual researchers.



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Research Highlights

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News & Views

  • The spiking phenomena associated with neural activity are characterized by an impressive degree of efficiency. The fabrication of a neuristor consisting of nanoscale components represents a step towards implementing such devices in integrated circuit applications.

    • Wei Lu
    News & Views
  • It has been shown that glasses prepared by physical vapour deposition have extraordinary stability. A computer algorithm that mimics such a process has now identified the optimal deposition temperature and the glasses' structural features.

    • Giorgio Parisi
    • Francesco Sciortino
    News & Views
  • Networks of glycans template multiphase lipid membranes, either by stabilizing large domains at the characteristic length scale of the network if inhomogeneous, or by suppressing macroscopic phase separation if homogeneous.

    • Jay T. Groves
    News & Views
  • Both electronic and nuclear spins have their pros and cons for quantum information processing. A silicon-based hybrid electronic–nuclear system can make the best of both properties.

    • Nan Zhao
    • Jörg Wrachtrup
    News & Views
  • A biocompatible method for fabricating three-dimensional photonic crystals opens up unique opportunities for structurally coloured biodegradable materials, but also for implantable biosensing and targeted therapeutics on the microscale.

    • Jennifer MacLeod
    • Federico Rosei
    News & Views
  • Electrocatalysis lies at the heart of the chemical phenomena that take place at electrochemical interfaces. In the future it will be the key to driving technological innovations that are urgently needed to deliver reliable, affordable and environmentally friendly energy.

    • Nenad M. Markovic
    News & Views
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  • Solid-state spin qubits offer promise as building blocks for quantum computers. Now, efficient quantum control is demonstrated over hybrid nuclear–electronic qubits in bismuth-doped silicon, as a consequence of the strong hyperfine interactions in this system.

    • Gavin W. Morley
    • Petra Lueders
    • Tania S. Monteiro
  • A critical component for chip-scale integrated photonics would be a non-reciprocal optical waveguide allowing light to travel in only one direction while reflecting it in the opposite one. Inspired by concepts of parity-time-symmetric quantum theories, a periodically modulated dielectric waveguide displaying unidirectional reflection is now demonstrated, reflecting light at telecom frequencies in only one direction.

    • Liang Feng
    • Ye-Long Xu
    • Axel Scherer
  • Emulating the spiking phenomena associated with neural activity in technological devices offers the promise of drastically improving their efficiency and scale. The fabrication of a neuristor that consists of nanoscale Mott memristors provides a step towards making such devices practical for integrated circuit applications.

    • Matthew D. Pickett
    • Gilberto Medeiros-Ribeiro
    • R. Stanley Williams
  • Determining crystal structures from diffraction experiments can be labour intensive and prone to errors. A hybrid approach combining experimental diffraction data, statistical symmetry information and first principles-based algorithmic optimization is now proposed to automatically solve crystal structures.

    • Bryce Meredig
    • C. Wolverton
  • The exterior surface of cell membranes in eukaryotes is surrounded by glycans. It is now found that the spatial configuration of these polysaccharide molecules controls the phase behaviour of multiphase lipid membranes—either by stabilizing ordered lipid domains or by suppressing macroscopic lipid phase separation—and that this glycan-induced patterning is thermally reversible.

    • Anand Bala Subramaniam
    • Guido Guidotti
    • Howard A. Stone
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  • Glasses with extraordinary kinetic stability have been made in the laboratory by physical vapour deposition. A computational algorithm that mimics such a deposition process now reveals that deposition at the temperature at which the configurational entropy vanishes leads to ultrastable glasses that are truly amorphous, pack uniformly and have energies that are equivalent to those of equilibrium supercooled liquids.

    • Sadanand Singh
    • M. D. Ediger
    • Juan J. de Pablo
  • Hydrogen embrittlement in metals has proved problematic for designing strong and reliable structural materials. Direct molecular dynamics simulations now reveal a ductile-to-brittle transition caused by the suppression of dislocation emission at the crack tip due to the aggregation of hydrogen.

    • Jun Song
    • W. A. Curtin
  • Photoconversion in organic photovoltaic cells, which relies on charge generation at donor/acceptor interfaces, is limited by short exciton-diffusion-lengths. Diluting an electron donor into a wide-energy-gap host material has now led to an ~50% increase in exciton diffusion length and enhanced power conversion efficiencies in planar heterojunction cells compared with optimized devices with an undiluted donor layer.

    • S. Matthew Menke
    • Wade A. Luhman
    • Russell J. Holmes
  • Semiconductor photoelectrodes for solar hydrogen production by water photoelectrolysis require stable and abundant visible-light absorbers such as iron oxide. Although this material suffers from poor transport properties for efficient charge-carrier generation and collection, these drawbacks can now be addressed by using resonant light trapping in ultrathin films designed as optical cavities.

    • Hen Dotan
    • Ofer Kfir
    • Avner Rothschild
  • Nanoplasmonic structures that can detect trace analytes via surface-enhanced Raman spectroscopy typically require sophisticated nanofabrication techniques. Self-assembly of gold nanoparticles into close-packed arrays at liquid/liquid and liquid/air interfaces is now used for the detection of multi-analytes from aqueous, organic or air phases.

    • Michael P. Cecchini
    • Vladimir A. Turek
    • Joshua B. Edel
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