Volume 5 Issue 11, November 2009

Volume 5 Issue 11

High-harmonic generation could be the basis of frequency combs for vacuum–ultraviolet wavelengths. But first we need a better understanding of harmonic orders produced at photon energies lower than the gas-ionization threshold. It is now shown that harmonics as low as the seventh have contributions from different quantum paths and that their temporal coherence is long enough for a frequency comb. Letter p815 Cover design by David Shand


  • Editorial |

    Peer review is the cornerstone of scientific publishing. But it isn't always clear exactly what Nature Physics expects of its referees — let us explain.


Books and Arts

Research Highlights

  • Research Highlights |

    The 2009 Nobel Prize in Physics has been awarded to Charles K. Kao for the development of optical fibres for telecommunications, and to Willard S. Boyle and George E. Smith for the invention of charge-coupled device sensors.

    • Ed Gerstner

News and Views

  • News & Views |

    Cold atoms and photons confined together in high-quality optical resonators self-organize into complicated crystalline structures that have an optical-wavelength scale. Complex solid-state phenomena can be studied in real time on directly observable scales.

    • Helmut Ritsch
  • News & Views |

    Proliferation of so-called anyonic defects in a topological phase of quantum matter leads to a critical state that can be visualized as a 'quantum foam', with topology-changing fluctuations on all length scales.

    • Kareljan Schoutens
  • News & Views |

    One way to collect data about black holes is to analyse the X-rays emitted from the surrounding plasmas heated to extreme temperatures by the flux of photons flowing into them. The use of intense lasers to recreate these conditions in the lab provides a potentially valuable tool for understanding what these data mean.

    • R. Paul Drake
  • News & Views |

    The discovery of iron-based pnictide superconductors may have reinvigorated the field of high-temperature superconductivity, but the cuprate superconductors are still in the game.

    • C. W. Chu


  • Letter |

    The ‘transmon’ design for superconducting qubits is particularly promising, owing to the long coherence times that it enables. Now, high-fidelity single-shot readout of such qubits — necessary for operating a quantum processor — has been demonstrated

    • François Mallet
    • , Florian R. Ong
    • , Agustin Palacios-Laloy
    • , François Nguyen
    • , Patrice Bertet
    • , Denis Vion
    •  & Daniel Esteve
  • Letter |

    The so-called hidden-order state in URu2Si2 is further obscured by conflicting experimental observations. A first-principles calculation shows that an order parameter with real and imaginary parts can explain many of these conflicts.

    • Kristjan Haule
    •  & Gabriel Kotliar
  • Letter |

    As well as providing subatomic-scale real-space images of metals, the scanning tunnelling microscope also reveals momentum–space information. Now it is possible to use this technique to image a heavy-electron liquid and obtain information on orbital structures.

    • Jinho Lee
    • , M. P. Allan
    • , M. A. Wang
    • , J. Farrell
    • , S. A. Grigera
    • , F. Baumberger
    • , J. C. Davis
    •  & A. P. Mackenzie
  • Letter |

    Similar to atoms in cold gases, exciton–polaritons in semiconductor microcavities can undergo Bose–Einstein condensation. A striking consequence of the appearance of macroscopic coherence in these systems is superfluidity. Now, clear evidence for such behaviour has been found in an exciton–polariton condensate.

    • Alberto Amo
    • , Jérôme Lefrère
    • , Simon Pigeon
    • , Claire Adrados
    • , Cristiano Ciuti
    • , Iacopo Carusotto
    • , Romuald Houdré
    • , Elisabeth Giacobino
    •  & Alberto Bramati
  • Letter |

    More efficient solar-energy conversion is possible if a single high-energy photon can be made to generate two electron–hole pairs in a cell, rather than a single pair plus heat. It is now shown that, contrary to expectation, this carrier multiplication is better in bulk semiconductor materials than in quantum dots.

    • J. J. H. Pijpers
    • , R. Ulbricht
    • , K. J. Tielrooij
    • , A. Osherov
    • , Y. Golan
    • , C. Delerue
    • , G. Allan
    •  & M. Bonn
  • Letter |

    Frequency combs have revolutionized frequency metrology. High-harmonic generation in atoms has led to fast sources of short-wavelength photons. Combining these two technologies enables the transfer of frequency combs to the vacuum-ultraviolet with potential applications in spectroscopy.

    • Dylan C. Yost
    • , Thomas R. Schibli
    • , Jun Ye
    • , Jennifer L. Tate
    • , James Hostetter
    • , Mette B. Gaarde
    •  & Kenneth J. Schafer
  • Letter |

    It has been suggested that the extreme states of matter generated by high-intensity lasers could allow conditions similar to those in the vicinity of black holes to be studied in the lab. The observation of striking similarities between the X-ray spectra emitted by a laser-driven laboratory plasma and those measured from two high-mass binary star systems suggests such potential has been realized.

    • Shinsuke Fujioka
    • , Hideaki Takabe
    • , Norimasa Yamamoto
    • , David Salzmann
    • , Feilu Wang
    • , Hiroaki Nishimura
    • , Yutong Li
    • , Quanli Dong
    • , Shoujun Wang
    • , Yi Zhang
    • , Yong-Joo Rhee
    • , Yong-Woo Lee
    • , Jae-Min Han
    • , Minoru Tanabe
    • , Takashi Fujiwara
    • , Yuto Nakabayashi
    • , Gang Zhao
    • , Jie Zhang
    •  & Kunioki Mima
  • Letter |

    High-intensity X-ray sources such as synchrotrons and free-electron lasers need large particle accelerators to drive them. The demonstration of a synchrotron X-ray source that uses a laser-driven particle accelerator could widen the availability of intense X-rays for research in physics, materials science and biology.

    • Matthias Fuchs
    • , Raphael Weingartner
    • , Antonia Popp
    • , Zsuzsanna Major
    • , Stefan Becker
    • , Jens Osterhoff
    • , Isabella Cortrie
    • , Benno Zeitler
    • , Rainer Hörlein
    • , George D. Tsakiris
    • , Ulrich Schramm
    • , Tom P. Rowlands-Rees
    • , Simon M. Hooker
    • , Dietrich Habs
    • , Ferenc Krausz
    • , Stefan Karsch
    •  & Florian Grüner


  • Article |

    Quantum many-body systems can show an elusive form of order known as topological order. Theoretical work now unifies several microscopic models whereby topological phases have been found, and predicts quantum phase transitions that are driven by quantum fluctuations of the topology.

    • Charlotte Gils
    • , Simon Trebst
    • , Alexei Kitaev
    • , Andreas W. W. Ludwig
    • , Matthias Troyer
    •  & Zhenghan Wang
  • Article |

    Ferromagnetism usually only occurs in materials containing elements that form covalent 3d and 4f bonds. Its occurrence in pure carbon is therefore surprising, even controversial. A systematic magnetic force microscope study indicates that ferromagnetism in graphite is the result of localized spins that arise at grain boundaries.

    • J. Červenka
    • , M. I. Katsnelson
    •  & C. F. J. Flipse
  • Article |

    Optical lattices, generated by interfering laser beams, provide a platform for observing condensed-matter phenomena in ultracold-atom systems. By extending the lattice idea to a multimode cavity, it should be possible to observe even more complex effects, such as frustration, crystallization, glass phases and supersolidity.

    • Sarang Gopalakrishnan
    • , Benjamin L. Lev
    •  & Paul M. Goldbart