Volume 4 Issue 9, September 2008

Volume 4 Issue 9

All electric and magnetic fields must satisfy Maxwell's equations. This constrains the shapes that field-lines can take. There are exotic solutions to Maxwell's equations that produce complex interlinked and knotted field-line topologies, but until now, it has not been clear how they might be generated. William Irvine and Dirk Bouwmeester study these solutions in the context of optical fields and propose experiments to create novel beams of light, which they expect to have applications ranging from particle trapping to plasma confinement. Letter p716

Cover design by David Shand

Editorial

  • Editorial |

    ...and thanks for all the physics: Bell Labs, home to major experimental and theoretical developments in twentieth-century physics, is turning away from fundamental research.

Thesis

Books and Arts

Research Highlights

News and Views

Letters

  • Letter |

    Quantum mechanics enables distant events to be more strongly correlated than is possible classically. The proposal for a new family of experimental tests, and the implementation of one of them, provides further insight into the nature of such non-local correlations.

    • Cyril Branciard
    • , Nicolas Brunner
    • , Nicolas Gisin
    • , Christian Kurtsiefer
    • , Antia Lamas-Linares
    • , Alexander Ling
    •  & Valerio Scarani
  • Letter |

    Micrometre-scale superconducting circuits can act as quantum two-level systems, but unlike in their natural counterparts—such as atoms—the parameters of these ‘artificial qubits’ can be controlled externally. This tunability has now been used to break the symmetry of the system hamiltonian in a controlled manner.

    • Frank Deppe
    • , Matteo Mariantoni
    • , E. P. Menzel
    • , A. Marx
    • , S. Saito
    • , K. Kakuyanagi
    • , H. Tanaka
    • , T. Meno
    • , K. Semba
    • , H. Takayanagi
    • , E. Solano
    •  & R. Gross
  • Letter |

    Coherent population trapping is a process by which a particle is induced to exist in a superposition of two ground states. This has now been demonstrated for an electron spin on a single quantum dot, which could prove useful in a variety of photonic and information-processing applications.

    • Xiaodong Xu
    • , Bo Sun
    • , Paul R. Berman
    • , Duncan G. Steel
    • , Allan S. Bracker
    • , Dan Gammon
    •  & L. J. Sham
  • Letter |

    The observation of so-called Bogoliubov excitations provides the first sign of possible superfluid behaviour in an exciton-polariton condensate.

    • S. Utsunomiya
    • , L. Tian
    • , G. Roumpos
    • , C. W. Lai
    • , N. Kumada
    • , T. Fujisawa
    • , M. Kuwata-Gonokami
    • , A. Löffler
    • , S. Höfling
    • , A. Forchel
    •  & Y. Yamamoto
  • Letter |

    When a superfluid—such as liquid helium—is set in rotation, vortices appear in which circulation around a closed loop can take only discrete values. Such quantized vortices have now been observed in a solid-state system—a Bose–Einstein condensate made of exciton polaritons.

    • K. G. Lagoudakis
    • , M. Wouters
    • , M. Richard
    • , A. Baas
    • , I. Carusotto
    • , R. André
    • , Le Si Dang
    •  & B. Deveaud-Plédran
  • Letter |

    Maxwell’s equations describing electric and magnetic fields limit the shapes field lines can take. But exotic solutions exist where the field lines are linked and knotted. A proposal now shows how such solutions could be realized experimentally.

    • William T. M. Irvine
    •  & Dirk Bouwmeester
  • Letter |

    Detailed analysis of multiscale structures and the identification of long-lived streamer-like wavemodes in a magnetically confined plasma provides new insight into the physics of plasma turbulence.

    • Takuma Yamada
    • , Sanae-I. Itoh
    • , Takashi Maruta
    • , Naohiro Kasuya
    • , Yoshihiko Nagashima
    • , Shunjiro Shinohara
    • , Kenichiro Terasaka
    • , Masatoshi Yagi
    • , Shigeru Inagaki
    • , Yoshinobu Kawai
    • , Akihide Fujisawa
    •  & Kimitaka Itoh

Articles

  • Article |

    A class of quantum-cryptographic protocols is proposed that involves back-and-forth communication between two parties. The approach is shown to provide enhanced security and should tolerate higher levels of noise and loss than conventional ‘one-way’ protocols.

    • Stefano Pirandola
    • , Stefano Mancini
    • , Seth Lloyd
    •  & Samuel L. Braunstein
  • Article |

    The experimental demonstration of a continuous and irreversible transfer of cold atoms from a ‘source mode’ to a ‘laser mode’ represents a step closer to a fully continuous atom laser.

    • Nicholas P. Robins
    • , Cristina Figl
    • , Matthew Jeppesen
    • , Graham R. Dennis
    •  & John D. Close
  • Article |

    Analysis of the best available data on the behaviour of a large number of glass-forming organic liquids suggests that the widespread belief that a glass ceases to flow below its transition temperature could be wrong.

    • Tina Hecksher
    • , Albena I. Nielsen
    • , Niels Boye Olsen
    •  & Jeppe C. Dyre

Futures