Volume 5 Issue 2, February 2009

Volume 5 Issue 2

The interaction between single atoms and the electromagnetic field can be enhanced using a cavity, the signature of strong coupling being 'vacuum Rabi splitting'. An experiment in which a superconducting circuit acts as an 'artificial atom' explores the physics beyond this linear-response effect and shows how nonlinear phenomena lead to the rich structure of the cavity transmission peaks shown on the cover. Letter p105

Cover design by David Shand

Editorial

  • Editorial |

    The inauguration of President Obama signals hope — and hope for science.

Thesis

Research Highlights

News and Views

  • News & Views |

    Many studies into the properties of the recently discovered ferropnictide superconductors lead to seemingly contradictory interpretations. Such discrepancies could be explained by the emergence of temporally fluctuating excitations formed by the antiphase boundaries between local spin-density-wave domains.

    • Warren E. Pickett
  • News & Views |

    Puzzling anisotropies in the cosmic microwave background radiation across the sky are leading some researchers to contemplate cosmology in an asymmetric universe.

    • David Wands
  • News & Views |

    In an ensemble of atoms with long-range dipolar interactions between them, only one atom can be excited at a time. This 'dipole blockade' has now been observed for two single atoms positioned at macroscopic distances.

    • Matthias Weidemüller
  • News & Views |

    A model for dense degenerate plasmas that incorporates electron spin indicates that quantum effects can be seen even under conditions previously considered to be in the classical regime.

    • Padma Kant Shukla
  • News & Views |

    Using dense plasmas instead of atomic or molecular gases could enable the generation of attosecond light pulses with higher energy, shorter durations and more energetic photons.

    • Fabien Quéré

Letters

  • Letter |

    Two independent experiments that demonstrate memories for single quantum excitations with storage times of the order of a millisecond—two orders of magnitude longer than reported so far—should help to bring practical long-distance quantum-communication networks a step closer.

    • Bo Zhao
    • , Yu-Ao Chen
    • , Xiao-Hui Bao
    • , Thorsten Strassel
    • , Chih-Sung Chuu
    • , Xian-Min Jin
    • , Jörg Schmiedmayer
    • , Zhen-Sheng Yuan
    • , Shuai Chen
    •  & Jian-Wei Pan
  • Letter |

    Two independent experiments that demonstrate memories for single quantum excitations with storage times on the order of a millisecond—two orders of magnitude longer than reported so far—should help to bring practical long-distance quantum-communication networks a step closer.

    • R. Zhao
    • , Y. O. Dudin
    • , S. D. Jenkins
    • , C. J. Campbell
    • , D. N. Matsukevich
    • , T. A. B. Kennedy
    •  & A. Kuzmich
  • Letter |

    The exploration of the Jaynes–Cummings Hamiltonian in a circuit-QED system—where an ‘artificial atom’ made of a superconducting circuit is strongly coupled to a microwave field—provides direct evidence for nonlinearities due to quantum mechanics on the level of single atoms and photons.

    • Lev S. Bishop
    • , J. M. Chow
    • , Jens Koch
    • , A. A. Houck
    • , M. H. Devoret
    • , E. Thuneberg
    • , S. M. Girvin
    •  & R. J. Schoelkopf
  • Letter |

    When two single Rydberg atoms—those having electrons in highly excited states—interact, one can be used to control the quantum state of the other. Two independent experiments now demonstrate a ‘Rydberg blockade’, an effect that might make long-range quantum gates between neutral atoms possible.

    • E. Urban
    • , T. A. Johnson
    • , T. Henage
    • , L. Isenhower
    • , D. D. Yavuz
    • , T. G. Walker
    •  & M. Saffman
  • Letter |

    When two single Rydberg atoms—those with electrons in highly excited states—interact, one can be used to control the quantum state of the other. Two independent experiments demonstrate such ‘Rydberg blockade’, an effect that might make long-range quantum gates between neutral atoms possible.

    • Alpha Gaëtan
    • , Yevhen Miroshnychenko
    • , Tatjana Wilk
    • , Amodsen Chotia
    • , Matthieu Viteau
    • , Daniel Comparat
    • , Pierre Pillet
    • , Antoine Browaeys
    •  & Philippe Grangier
  • Letter |

    ARPES measurements of the ‘failed’ superconductor LBCO-1/8 suggest that its pseudogap phase consists of two distinct components. The result could be an important clue into the nature of this phase in the copper oxide superconductors.

    • Rui-Hua He
    • , Kiyohisa Tanaka
    • , Sung-Kwan Mo
    • , Takao Sasagawa
    • , Masaki Fujita
    • , Tadashi Adachi
    • , Norman Mannella
    • , Kazuyoshi Yamada
    • , Yoji Koike
    • , Zahid Hussain
    •  & Zhi-Xun Shen
  • Letter |

    An experiment demonstrating the generation of subfemtosecond pulses of light through the interaction of laser light with a solid target underlines the potential of this approach to lead to a new generation of intense sources of attosecond pulses.

    • Y. Nomura
    • , R. Hörlein
    • , P. Tzallas
    • , B. Dromey
    • , S. Rykovanov
    • , Zs. Major
    • , J. Osterhoff
    • , S. Karsch
    • , L. Veisz
    • , M. Zepf
    • , D. Charalambidis
    • , F. Krausz
    •  & G. D. Tsakiris
  • Letter |

    Techniques for reconstructing an object’s microstructure from its diffraction pattern have substantially improved the future imaging potential of next-generation X-ray sources. Yet the same techniques can already be applied to conventional electron microscopes, to extend their resolution to below an ångström.

    • W. J. Huang
    • , J. M. Zuo
    • , B. Jiang
    • , K. W. Kwon
    •  & Moonsub Shim

Articles

  • Article |

    A general approach to simplifying quantum logic circuits—the ‘programs’ of quantum computers—is described and demonstrated on a platform based on photonic qubits.

    • Benjamin P. Lanyon
    • , Marco Barbieri
    • , Marcelo P. Almeida
    • , Thomas Jennewein
    • , Timothy C. Ralph
    • , Kevin J. Resch
    • , Geoff J. Pryde
    • , Jeremy L. O’Brien
    • , Alexei Gilchrist
    •  & Andrew G. White
  • Article |

    Many studies on the properties of the recently discovered ferropnictide superconductors report seemingly contradictory results. A theoretical study suggests that these contradictions might be resolved by considering such materials as having a strongly magnetic ground state whose domain boundaries fluctuate, preventing their experimental detection.

    • I. I. Mazin
    •  & M. D. Johannes
  • Article |

    A systematic demonstration of the generation and focusing of laser-driven high-order harmonics to a near-diffraction-limited spot suggests that scaling this approach to ever higher intensities could be easier than first thought.

    • B. Dromey
    • , D. Adams
    • , R. Hörlein
    • , Y. Nomura
    • , S. G. Rykovanov
    • , D. C. Carroll
    • , P. S. Foster
    • , S. Kar
    • , K. Markey
    • , P. McKenna
    • , D. Neely
    • , M. Geissler
    • , G. D. Tsakiris
    •  & M. Zepf
  • Article |

    The force between molecules deposited on a surface during the growth of an organic film is usually attractive. But for certain metal phthalocyanine molecules, this force can change with temperature from attractive to repulsive, resulting in unusual ordering behaviour.

    • Christoph Stadler
    • , Sören Hansen
    • , Ingo Kröger
    • , Christian Kumpf
    •  & Eberhard Umbach

Corrigendum