Volume 6 Issue 4, April 2010

Volume 6 Issue 4

Superconducting quantum interference devices based on the Josephson effect have enabled significant improvements in the sensitivity of magnetic-field measurements. Similar devices that incorporate sections of non-superconducting metal into a superconducting ring exploit a phenomenon known as the proximity effect to realize further improvements in magnetic-field sensitivity. Letter p254 Cover design by David Shand

Editorial

  • Editorial |

    In a time of recession, will a new UK government invest sufficiently in science?

Correspondence

Commentary

  • Commentary |

    Astronomy is becoming 'big science'. Although the transformation brings the experimental clout to answer the biggest questions, it also carries risks for the field's future.

    • Leslie Sage
    •  & Joanne Baker

Thesis

Books and Arts

Research Highlights

News and Views

  • News & Views |

    Laser-driven particle accelerators can accelerate electrons to energies in excess of 1 GeV over a distance of just a few centimetres. An innovative technique that drastically reduces the computational demands of simulating laser–plasma interactions should help increase this to tens of gigaelectronvolts.

    • Raoul M. G. M. Trines
  • News & Views |

    Achieving full control over all internal and external degrees of freedom of a molecule has been a long-standing goal in molecular physics. Newly developed methods to prepare translationally, vibrationally and rotationally cold molecular ions have brought this target one step closer.

    • Stefan Willitsch
  • News & Views |

    Long γ-ray bursts are associated with core-collapse supernovae. The connection reveals a rich and diverse continuum of explosions, in which the energy is partitioned between relativistic and non-relativistic flows.

    • Dieter H. Hartmann
  • News & Views |

    Lasing and strong coupling can coexist in a single quantum dot coupled to a photonic-crystal-nanocavity mode. This provides important clues towards the realization of a single-quantum-dot nanolaser.

    • Stefan Strauf
  • News & Views |

    Observations of half-integer transitions of the quantized magnetic flux passing through a superconducting niobium/iron-pnictide loop provides strong evidence for the occurrence of unconventional 'sign-reversal s-wave pairing symmetry' in the iron-based superconductors.

    • Ying Liu
  • News & Views |

    'Random lasing' in disordered materials was first shown over 20 years ago, but the mechanism by which it occurs is much debated. High-resolution imaging correlated to the excitation of random lasing from natural resonant cavities in conjugated polymers suggests there are many overlapping regimes and generation mechanisms involved.

    • Nabil M. Lawandy

Letters

  • Letter |

    Nitrogen–vacancy centres in diamond have emerged as a promising platform for quantum information processing at room temperature. Now, coherent coupling between two electron spins separated by almost 10 nm has been demonstrated. At this distance, the spins can be addressed individually, which might enable the construction of a network of connected quantum registers.

    • P. Neumann
    • , R. Kolesov
    • , B. Naydenov
    • , J. Beck
    • , F. Rempp
    • , M. Steiner
    • , V. Jacques
    • , G. Balasubramanian
    • , M. L. Markham
    • , D. J. Twitchen
    • , S. Pezzagna
    • , J. Meijer
    • , J. Twamley
    • , F. Jelezko
    •  & J. Wrachtrup
  • Letter |

    The development of superconducting quantum interference devices based on the Josephson effect has led to significant improvements in our ability to measure magnetic fields. A similar device, dubbed the superconducting quantum interference transistor, which exploits the proximity effect, could allow similar significant further improvements.

    • Francesco Giazotto
    • , Joonas T. Peltonen
    • , Matthias Meschke
    •  & Jukka P. Pekola
  • Letter |

    Measurements of integer and half-integer transitions of the quantized magnetic flux through a superconducting niobium–iron pnictide ring provide strong evidence to support predictions that the Cooper pairs within iron-based superconductors show an unconventional ‘reversed s-wave symmetry’.

    • C.-T. Chen
    • , C. C. Tsuei
    • , M. B. Ketchen
    • , Z.-A. Ren
    •  & Z. X. Zhao
  • Letter |

    Cooling molecules to ultralow temperatures is difficult owing to the fact they have many degrees of freedom. Now, a dense cloud of molecules in their lowest vibrational and rotational level has been prepared in an optical lattice, paving the way to Bose–Einstein condensation of ground-state molecules.

    • Johann G. Danzl
    • , Manfred J. Mark
    • , Elmar Haller
    • , Mattias Gustavsson
    • , Russell Hart
    • , Jesus Aldegunde
    • , Jeremy M. Hutson
    •  & Hanns-Christoph Nägerl
  • Letter |

    Molecular targets prepared in well-defined quantum states play an essential part in a wide range of fields, from metrology to astrochemistry. Now, MgH+ ions have been prepared in their lowest vibrational and rotational level using a laser-cooling scheme. This provides a fresh approach for exploring such phenomena and applications experimentally.

    • Peter F. Staanum
    • , Klaus Højbjerre
    • , Peter S. Skyt
    • , Anders K. Hansen
    •  & Michael Drewsen
  • Letter |

    Molecular targets prepared in well-defined quantum states play an essential part in a wide range of fields, from metrology to astrochemistry. Now, HD+ ions have been prepared in their lowest vibrational and rotational level using a laser-cooling scheme. This provides a fresh approach for exploring such phenomena and applications experimentally.

    • T. Schneider
    • , B. Roth
    • , H. Duncker
    • , I. Ernsting
    •  & S. Schiller
  • Letter |

    Laser oscillations have now been observed in a solid-state system composed of an InAs quantum dot strongly coupled to the optical modes of a GaAs photonic-crystal cavity. Signs of lasing in the system are observed as the optical pump power is increased but before the strong coupling is lost.

    • M. Nomura
    • , N. Kumagai
    • , S. Iwamoto
    • , Y. Ota
    •  & Y. Arakawa

Articles

  • Article |

    Axions are hypothetical particles that might play an important part in particle physics, astrophysics and cosmology. So far they have eluded observation, but theoretical work now predicts that axion physics might be explored in condensed-matter systems known as topological insulators.

    • Rundong Li
    • , Jing Wang
    • , Xiao-Liang Qi
    •  & Shou-Cheng Zhang
  • Article |

    Building on ideas from quantum information science and on recent experimental advances, the use of ultracold alkaline-earth atoms in optical lattices as quantum simulators of many-body phenomena is proposed. The corresponding models possess a high degree of symmetry and may provide fundamental insights into strongly correlated systems.

    • A. V. Gorshkov
    • , M. Hermele
    • , V. Gurarie
    • , C. Xu
    • , P. S. Julienne
    • , J. Ye
    • , P. Zoller
    • , E. Demler
    • , M. D. Lukin
    •  & A. M. Rey
  • Article |

    The minimum noise energy that a phase-preserving amplifier adds to the signal is fundamentally limited to half a photon. A proposed parametric amplifier based on Josephson junctions should be able to reach this limit at microwave frequencies.

    • N. Bergeal
    • , R. Vijay
    • , V. E. Manucharyan
    • , I. Siddiqi
    • , R. J. Schoelkopf
    • , S. M. Girvin
    •  & M. H. Devoret
  • Article |

    Although ‘random lasing’ in disordered optical media was first demonstrated a decade ago, the mechanism by which it occurs is disputed. New evidence of random lasing in conjugated polymers strongly supports the notion that it is generated within random optical cavities that naturally occur within disordered media.

    • A. Tulek
    • , R. C. Polson
    •  & Z. V. Vardeny
  • Article |

    Modelling the interaction of an intense laser with a plasma in an optimal ‘Lorentz boosted’ frame of reference decreases by many orders of magnitude the computation time needed to simulate a laser-driven particle accelerator. This provides a powerful tool for optimizing the characteristics of accelerators driven by the next generation of high-intensity lasers, which will be able to deliver powers beyond a petawatt.

    • S. F. Martins
    • , R. A. Fonseca
    • , W. Lu
    • , W. B. Mori
    •  & L. O. Silva

Correction