Physical sciences articles within Nature

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  • Letter |

    Ultracold polar molecules offer the possibility of exploring quantum gases with interparticle interactions that are strong, long-range and spatially anisotropic. Here, dipolar collisions in an ultracold gas of fermionic potassium–rubidium molecules have been experimentally observed. The results show how the long-range dipolar interaction can be used for electric-field control of chemical reaction rates in an ultracold gas of polar molecules.

    • K.-K. Ni
    • , S. Ospelkaus
    •  & D. S. Jin

  • Letter |

    It has been suggested that Earth's current supply of water was delivered by asteroids. The presence of water on the surface of some asteroids has been inferred from the comet-like activity of several small asteroids, including two members of the Themis dynamical family, but hitherto has not been measured. Here, infrared spectra of the asteroid 24 Themis are reported; the results show that ice and organic compounds are not only present, but also prevalent, on its surface.

    • Humberto Campins
    • , Kelsey Hargrove
    •  & Julie Ziffer

  • Letter |

    A major pursuit in the chemical community involves the search for efficient and inexpensive catalysts that can produce large quantities of hydrogen gas from water. Here, a molybdenum-oxo complex has been identified that can catalytically generate hydrogen gas either from pure water at neutral pH, or from sea water. The work has implications for the design of 'green' chemistry cycles.

    • Hemamala I. Karunadasa
    • , Christopher J. Chang
    •  & Jeffrey R. Long

  • Letter |

    Light beams can be engineered to carry orbital angular momentum, with application as, for instance, optical 'spanners' — essentially a 'twisted' variant of the more familiar optical tweezers. Here it is shown that it is, in principle, possible to engineer similar behaviour into an electron beam. Such a beam could find use in a variety of spectroscopy and microscopy techniques.

    • Masaya Uchida
    •  & Akira Tonomura

  • Article |

    A phase transition occurs when a physical system suddenly changes state, for instance when it melts or freezes. The Dicke model describes a collective matter–light interaction and has been predicted to show a quantum phase transition. Here, this quantum phase transition has been realized in an open system formed by a Bose–Einstein condensate coupled to an optical cavity. Surprisingly, the atoms are observed to self-organize into a supersolid phase.

    • Kristian Baumann
    • , Christine Guerlin
    •  & Tilman Esslinger

  • News & Views |

    Non-Abelian anyons are hypothesized particles that, if found, could form the basis of a fault-tolerant quantum computer. The theoretical finding that they may turn up in three dimensions comes as a surprise.

    • Chetan Nayak

  • News & Views |

    Researchers have long wanted to be able to control macroscopic mechanical objects in their smallest possible state of motion. Success in achieving that goal heralds a new generation of quantum experiments.

    • Markus Aspelmeyer

  • Letter |

    Atom chips provide a versatile quantum laboratory for experiments with ultracold atomic gases, but techniques to control atomic interactions and to generate entanglement have been unavailable so far. Here, the experimental generation of multi-particle entanglement on an atom chip is described. The technique is used to produce spin-squeezed states of a two-component Bose–Einstein condensate, which should be useful for quantum metrology.

    • Max F. Riedel
    • , Pascal Böhi
    •  & Philipp Treutlein

  • Letter |

    The precision of interferometers — used in metrology and in the state-of-the-art time standard — is generally limited by classical statistics. Here it is shown that the classical precision limit can be beaten by using nonlinear atom interferometry with Bose–Einstein condensates.

    • C. Gross
    • , T. Zibold
    •  & M. K. Oberthaler

  • Column |

    The US defence department should be at the centre of the nation's energy policy, says Daniel Sarewitz.

    • Daniel Sarewitz

  • Letter |

    Thermophilic bacteria and archaea use carbon dioxide or carbon monoxide as a starting material for making the organic substances used in cellular molecules. A central enzyme in this pathway has now been discovered, namely fructose 1,6-bisphosphate aldolase/phosphatase. This enzyme might represent the ancestral gluconeogenic enzyme.

    • Rafael F. Say
    •  & Georg Fuchs

  • Letter |

    Many functional materials can be created by directing the assembly of colloidal particles into a desired structure. Control over particle assembly usually involves the use of molecules such as DNA that can recognize and bind each other. Here, a simple and effective alternative is described. Colloidal spheres serve as keys, and monodisperse colloidal particles with a spherical cavity as locks. These will spontaneously and reversibly bind to each other via the depletion interaction if their sizes match.

    • S. Sacanna
    • , W. T. M. Irvine
    •  & D. J. Pine

  • Letter |

    The main observational signature of star-forming galaxies at the highest redshifts is the Lyman-α (Lyα) emission line. But Lyα photons scatter in the neutral interstellar medium of their host galaxies, and may therefore be greatly absorbed by interstellar dust. It is now shown that the average escaping fraction of Lyα photons from star-forming galaxies at redshift z = 2.2 is just 5 per cent. This implies that numerous conclusions based on Lyα-selected samples will require upwards revision by an order of magnitude.

    • Matthew Hayes
    • , Göran Östlin
    •  & Jens Melinder

  • Letter |

    An imaging technique that could identify all the individual atoms, including defects, in a material would be a useful tool. Here an electron-microscopy approach to the problem, based on annular dark-field imaging, is described. A monolayer of boron nitride was studied, and three types of atomic substitution were identified. Careful analysis of the data enabled the construction of a detailed map of the atomic structure.

    • Ondrej L. Krivanek
    • , Matthew F. Chisholm
    •  & Stephen J. Pennycook

  • Letter |

    A two-dimensional gas of electrons is a powerful test-bed for the fundamental physics of interacting particles, and has been much studied in the context of integer and fractional quantum Hall effects. The latest observations of this system reveal prominent structure in the high energy single particle spectrum that cannot be readily explained with existing models of this system.

    • O. E. Dial
    • , R. C. Ashoori
    •  & K. W. West

  • News & Views |

    Colloid particles that form bonds to each other at specific orientations might self-assemble into all sorts of useful materials. The key — and the lock — to such binding has been discovered.

    • Michael J. Solomon

  • News Feature |

    Social scientists have embedded themselves at CERN to study the world's biggest research collaboration. Zeeya Merali reports on a 10,000-person physics project.

    • Zeeya Merali

  • Letter |

    Massive galaxies in the early Universe have been shown to be forming stars at high rates. Probing the properties of individual star-forming regions is beyond the resolution and sensitivity of existing telescopes. Here, however, observations are reported of the galaxy SMMJ2135–0102 at redshift z=2.3259, which has been gravitationally magnified by a factor of 32 by a galaxy cluster lens in the foreground. The physics underlying star formation here is similar to that in local galaxies, but the energetics are very different.

    • A. M. Swinbank
    • , I. Smail
    •  & J. D. Younger

  • News |

    Atomically thin carbon sheets offer bacteria a protective shell in electron microscopes.

    • Geoff Brumfiel

  • Letter |

    Until now, quantum atomic gases and single trapped ions have been treated separately in experiments. Now a hybrid system has been investigated, involving the immersion of a single trapped ion into a Bose–Einstein condensate of neutral atoms. The two systems could be controlled independently and the fundamental interaction processes were studied. Sympathetic cooling of the single ion by the condensate was observed, hinting at the possibility of using these condensates as refrigerators for ion-trap quantum computers.

    • Christoph Zipkes
    • , Stefan Palzer
    •  & Michael Köhl

  • Letter |

    Surface-enhanced Raman scattering is a powerful spectroscopy technique that can be used to study substances down to the level of single molecules. But the practical applications have been limited by the need for metal substrates with roughened surfaces or in the form of nanoparticles. Here a new approach — shell-insulated nanoparticle-enhanced Raman spectroscopy — is described, and its versatility demonstrated with numerous test substances.

    • Jian Feng Li
    • , Yi Fan Huang
    •  & Zhong Qun Tian

  • Letter |

    The physics of thermal diffusion — mass diffusion driven by a temperature gradient — is poorly understood. One obstacle has been that the Soret coefficient (ST, which describes the steady-state result of thermal diffusion) is sensitive to many factors. It is now shown that the difference in ST between isotopes of diffusing elements that are network modifiers is independent of composition and temperature. The findings suggest a theoretical approach for describing thermal diffusion in silicate melts and other complex solutions.

    • F. Huang
    • , P. Chakraborty
    •  & C. E. Lesher

  • Letter |

    The most distant quasars known, at redshifts z ≈ 6, generally have the same properties as lower-redshift quasars, implying that although the Universe was young at z ≈ 6, such quasars are still evolved objects. One z ≈ 6 quasar was shown to have no detectable emission from hot dust, but it was not clear whether it was an outlier. Now, a second quasar without hot-dust emission has been discovered in a sample of 21 z ≈ 6 quasars. Moreover, hot-dust abundance in these quasars builds up as the central black hole grows.

    • Linhua Jiang
    • , Xiaohui Fan
    •  & Fabian Walter

  • Letter |

    Of the more than 400 known exoplanets, about 70 transit their central star, most in small orbits (with periods of around 1 day, for instance). Here, observations are reported of the transit of CoRoT-9b, which orbits with a period of 95.274 days, on a low eccentricity, around a solar-like star. Its relatively large periastron distance yields a 'temperate' photospheric temperature estimated to be between 250 and 430 K, and its interior composition is inferred to be consistent with those of Jupiter and Saturn.

    • H. J. Deeg
    • , C. Moutou
    •  & G. Wuchterl

  • News & Views |

    The golden ratio — an exact 'magic' number often claimed to be observed when taking ratios of distances in ancient and modern architecture, sculpture and painting — has been spotted in a magnetic compound.

    • Ian Affleck

  • News & Views |

    The discovery of two quasars in the distant Universe that apparently have no hot dust in their environments provides evidence that these systems represent the first generation of their family.

    • Giulia Stratta

  • News & Views |

    Gold nanoparticles coated with a thin layer of an oxide allow molecules adsorbed on surfaces as diverse as those of platinum, yeast cells or citrus fruits to be characterized routinely in the laboratory.

    • Martin Moskovits

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