Volume 8 Issue 3, March 2012

Volume 8 Issue 3

Rapid particle acceleration is possible using a fixed-field alternating-gradient machine — but 'scaling' in its design has been necessary to avoid beam blow-up and loss. The demonstration now of acceleration in such a machine without scaling has positive implications for future particle accelerators. Article p243 COVER IMAGE: ANDREW COLLINS COVER DESIGN: ALLEN BEATTIE

The cover image of the March 2012 issue of Nature Physics should have been credited to Andrew Collins. Corrected in the HTML and PDF versions after print, 12 March 2012.

Editorial

  • Editorial |

    Two big-science projects — the Large Hadron Collider and the Planck satellite — are set to deliver major results in the coming year.

Correspondence

Thesis

Books and Arts

Research Highlights

News and Views

  • News & Views |

    A single photon can alter the shape of a molecule. It is now shown that quantum effects can play an important role in this change leading to conformation relaxation rates hundreds of times faster than previously expected.

    • Shaul Mukamel
  • News & Views |

    Brillouin scattering of light is now shown to attenuate the Brownian motion of microscopic acoustic resonators. This electrostrictive phenomenon could be a useful complement to the ponderomotive and photothermal effects that can optically control optomechanical systems.

    • Ivan Favero
  • News & Views |

    Geomagnetic storms driven by the solar wind can cause the flux of high-energy electrons in the Earth's Van Allen belts to rapidly fall. Analysis of data obtained during one such event from multiple spacecraft located at different altitudes in the magnetosphere reveals just where these electrons go.

    • Mary K. Hudson
  • News & Views |

    A macroscopic quantum pendulum has now been created by confining a polariton condensate in a parabolic optical trap. Spectacular images of multiparticle wavefunctions are obtained by purely optical means.

    • Alexey Kavokin

Letters

  • Letter |

    According to Heisenberg, the more precisely, say, the position of a particle is measured, the less precisely we can determine its momentum. The uncertainty principle in its original form ignores, however, the unavoidable effect of recoil in the measuring device. An experimental test now validates an alternative relation, and the uncertainty principle in its original formulation is broken.

    • Jacqueline Erhart
    • , Stephan Sponar
    • , Georg Sulyok
    • , Gerald Badurek
    • , Masanao Ozawa
    •  & Yuji Hasegawa
  • Letter |

    Polaritons—quasiparticles made up of a photon and exciton strongly coupled together—can form macroscopic quantum states even at room temperature. Now these so-called condensates are imaged directly. This achievement could aid the development of semiconductor-based polariton-condensate devices.

    • G. Tosi
    • , G. Christmann
    • , N. G. Berloff
    • , P. Tsotsis
    • , T. Gao
    • , Z. Hatzopoulos
    • , P. G. Savvidis
    •  & J. J. Baumberg
  • Letter |

    Measurements of Hanbury Brown and Twiss correlations in atomic gases near the Bose–Einstein condensation threshold reveal strong signatures of interactions between the constituent atoms, and establish such correlation measurements as a sensitive probe for the quantum properties of matter-wave sources.

    • A. Perrin
    • , R. Bücker
    • , S. Manz
    • , T. Betz
    • , C. Koller
    • , T. Plisson
    • , T. Schumm
    •  & J. Schmiedmayer
  • Letter |

    The presence, or otherwise, of magnetism in graphene has been the subject of much debate. A systematic study of point defects—a widely suggested source of ferromagnetism in graphene—suggests that although they can exhibit net spin, they remain paramagnetic, even at liquid helium temperature.

    • R. R. Nair
    • , M. Sepioni
    • , I-Ling Tsai
    • , O. Lehtinen
    • , J. Keinonen
    • , A. V. Krasheninnikov
    • , T. Thomson
    • , A. K. Geim
    •  & I. V. Grigorieva
  • Letter |

    A novel mechanism for cooling tiny mechanical resonators is now demonstrated. Inelastic scattering of light from phonons in an electrostrictive material attenuates the Brownian motion of the mechanical mode.

    • Gaurav Bahl
    • , Matthew Tomes
    • , Florian Marquardt
    •  & Tal Carmon
  • Letter |

    Geomagnetic storms driven by the solar wind can cause a dramatic drop in the flux of high-energy electrons in the Earth’s outer Van Allen belt. Analysis of data obtained during such an event by three different sets of spacecraft suggests that these electrons are directed into space rather than lost to the atmosphere.

    • Drew L. Turner
    • , Yuri Shprits
    • , Michael Hartinger
    •  & Vassilis Angelopoulos

Articles

  • Article |

    The transport measurements of an interacting fermionic quantum gas in an optical lattice provide a direct experimental realization of the Hubbard model—one of the central models for interacting electrons in solids—and give insights into the transport properties of many-body phases in condensed-matter physics.

    • Ulrich Schneider
    • , Lucia Hackermüller
    • , Jens Philipp Ronzheimer
    • , Sebastian Will
    • , Simon Braun
    • , Thorsten Best
    • , Immanuel Bloch
    • , Eugene Demler
    • , Stephan Mandt
    • , David Rasch
    •  & Achim Rosch
  • Article |

    Superfluorescence—the emission of coherent light from an initially incoherent collection of excited dipoles—is now identified in a semiconductor. Laser-excited electron–hole pairs spontaneously polarize and then abruptly decay to produce intense pulses of light.

    • G. Timothy Noe II
    • , Ji-Hee Kim
    • , Jinho Lee
    • , Yongrui Wang
    • , Aleksander K. Wójcik
    • , Stephen A. McGill
    • , David H. Reitze
    • , Alexey A. Belyanin
    •  & Junichiro Kono
  • Article |

    A molecule can alter shape as it absorbs a photon. It is now shown that quantum effects can play an important role in this change leading to conformation rates hundreds of times faster than previously expected.

    • J. Clark
    • , T. Nelson
    • , S. Tretiak
    • , G. Cirmi
    •  & G. Lanzani
  • Article |

    Individual molecules are now deterministically trapped in few-femtosecond laser pulses. This molecular conveyer belt may become a useful tool for probing ultrafast molecular dynamics.

    • Steffen Kahra
    • , Günther Leschhorn
    • , Markus Kowalewski
    • , Agustin Schiffrin
    • , Elisabeth Bothschafter
    • , Werner Fuß
    • , Regina de Vivie-Riedle
    • , Ralph Ernstorfer
    • , Ferenc Krausz
    • , Reinhard Kienberger
    •  & Tobias Schaetz
  • Article |

    Rapid particle acceleration is possible using a fixed-field alternating-gradient machine—but ‘scaling’ in its design has been necessary to avoid beam blow-up and loss. The demonstration now of acceleration in such a machine without scaling has positive implications for future particle accelerators.

    • S. Machida
    • , R. Barlow
    • , J. S. Berg
    • , N. Bliss
    • , R. K. Buckley
    • , J. A. Clarke
    • , M. K. Craddock
    • , R. D’Arcy
    • , R. Edgecock
    • , J. M. Garland
    • , Y. Giboudot
    • , P. Goudket
    • , S. Griffiths
    • , C. Hill
    • , S. F. Hill
    • , K. M. Hock
    • , D. J. Holder
    • , M. G. Ibison
    • , F. Jackson
    • , S. P. Jamison
    • , C. Johnstone
    • , J. K. Jones
    • , L. B. Jones
    • , A. Kalinin
    • , E. Keil
    • , D. J. Kelliher
    • , I. W. Kirkman
    • , S. Koscielniak
    • , K. Marinov
    • , N. Marks
    • , B. Martlew
    • , P. A. McIntosh
    • , J. W. McKenzie
    • , F. Méot
    • , K. J. Middleman
    • , A. Moss
    • , B. D. Muratori
    • , J. Orrett
    • , H. L. Owen
    • , J. Pasternak
    • , K. J. Peach
    • , M. W. Poole
    • , Y-N. Rao
    • , Y. Saveliev
    • , D. J. Scott
    • , S. L. Sheehy
    • , B. J. A. Shepherd
    • , R. Smith
    • , S. L. Smith
    • , D. Trbojevic
    • , S. Tzenov
    • , T. Weston
    • , A. Wheelhouse
    • , P. H. Williams
    • , A. Wolski
    •  & T. Yokoi