Volume 3 Issue 8, August 2007

Volume 3 Issue 8

Superconductors, superfluids and supersolids can be defined in terms of how they respond to rotation. According to the London law, a rotating superconductor will generate a magnetic field that depends on fundamental constants alone. And for superfluids composed of neutral particles, such as helium-4, rotation velocities above a certain threshold will result in the formation of vortices; the quantization of the superfluid velocity within a vortex is known as Onsager-Feynman quantization. Both of these laws would be broken by a two-component superconductor, propose Egor Babaev and Neil Ashcroft. They show that for liquid metallic hydrogen, in which Cooper pairs can be formed through electron pairing and proton pairing, the superfluid velocity quantization becomes fractional and the generated magnetic field no longer depends only on fundamental constants but on density as well.

[Letter p530]

Editorial

  • Editorial |

    Britain has a new leader, and with him a new science minister in a new department: would you guess that the 'Department of Innovation, Universities and Skills' now holds the remit for science?

Thesis

Books and Arts

Research Highlights

News and Views

  • News & Views |

    Weather is a familiar phenomenon on Earth, but it's quite unexpected on a star, in particular when the clouds consist of heavy elements. Let's talk about the weather.

    • George W. Preston
  • News & Views |

    Proof that the delicate 5/2 fractional quantum Hall state survives constriction within a quantum point contact paves the way to realizing an experimental platform for exploring the bizarre world of non-abelian particle statistics.

    • Vladimir J. Goldman
  • News & Views |

    Magnetic domains in a thin film grow in a jerky manner as avalanches of spins flip their directions. At low temperatures, the measured distribution of avalanche sizes agrees with one theory; at high temperatures, with another.

    • James P. Sethna
  • News & Views |

    Can we ever know what happened before the Big Bang? It may have been only a stage in the existence of our Universe rather than its beginning, but analysis suggests the Big Bang is a barrier beyond which we may never see with clarity.

    • Carlo Rovelli
  • News & Views |

    An efficient way to transport electron spins from a ferromagnet into silicon essentially makes silicon magnetic, and provides an exciting step towards integration of magnetism and mainstream semiconductor electronics.

    • Ron Jansen

Letters

Articles

Futures

  • Futures |

    A degree of progress.

    • Craig DeLancey