Volume 13 Issue 2, February 2017

Volume 13 Issue 2

Superconducting circuits, coupled to form a ring in which a photonic excitation can circulate between sites, are established as a versatile platform for studying the interplay of strong particle interactions and external fields. Article p146; News & Views p110 IMAGE: M. FANG/MARTINIS LAB, UCSB COVER DESIGN: BETHANY VUKOMANOVIC

Editorial

  • Editorial |

    History and cultural depth are assets that benefit Indian science. But do they also hinder it?

Thesis

Commentary

  • Commentary |

    Physics teaching in schools could be transformed by highlighting its role in the animal kingdom.

    • Matin Durrani

Research Highlights

News and Views

  • News & Views |

    Experiments of the Aharonov–Bohm type typically involve particles that are charged and interact with a magnetic flux. Photons aren't the former and don't do the latter. Yet, an Aharonov–Bohm ring for photons has just been realized experimentally.

    • Ady Stern
  • News & Views |

    Not in all superconductors do Cooper pairs respect the lattice symmetry of the crystal in which they move. Now, work finds such 'picky' Cooper pairs in the presence of strong electron–spin interaction — and gives rise to an entire host of new questions.

    • Kamran Behnia
  • News & Views |

    Two independent teams have demonstrated that the current-driven motion of a topological charge experiences a transverse deflection analogous to charged particles in the classical Hall effect.

    • Gong Chen
  • News & Views |

    The discovery of intermediate high-spin multiexciton states with surprisingly long lifetimes provides new opportunities for engineering singlet fission, which may also provide an intriguing route to quantum information and spintronic applications.

    • Michael R. Wasielewski
  • News & Views |

    The coexistence of spin order and disorder at a critical point in the phase diagram of multiferroic materials may be exploited to locally control magnetoelectric coupling — as is now shown for doped BiFeO3 by means of scanning probe microscopy.

    • Sergei V. Kalinin

Letters

  • Letter |

    A detailed and systematic neutron-scattering study uncovers a continuum of magnetic excitations down to 0.06 K in the triangular quantum magnet YbMgGaO4 — an observation consistent with quantum spin liquid behaviour.

    • Joseph A. M. Paddison
    • , Marcus Daum
    • , Zhiling Dun
    • , Georg Ehlers
    • , Yaohua Liu
    • , Matthew B. Stone
    • , Haidong Zhou
    •  & Martin Mourigal
  • Letter |

    In a nematic liquid crystal, electron orbitals align themselves along one axis, as rods. Thermodynamic observations of such rod-like alignments in CuxBi2Se3 provide evidence for a nematic superconductor.

    • Shingo Yonezawa
    • , Kengo Tajiri
    • , Suguru Nakata
    • , Yuki Nagai
    • , Zhiwei Wang
    • , Kouji Segawa
    • , Yoichi Ando
    •  & Yoshiteru Maeno
  • Letter |

    The emergence of optically silent phonons show that strong interlayer electron–phonon coupling can arise in van der Waals heterostructures, with the vibrational modes in one layer coupling to the electronic states in a neighbouring layer.

    • Chenhao Jin
    • , Jonghwan Kim
    • , Joonki Suh
    • , Zhiwen Shi
    • , Bin Chen
    • , Xi Fan
    • , Matthew Kam
    • , Kenji Watanabe
    • , Takashi Taniguchi
    • , Sefaattin Tongay
    • , Alex Zettl
    • , Junqiao Wu
    •  & Feng Wang
  • Letter |

    Light can be used to directly excite phonon modes in condensed matter. Simultaneously exciting several modes in an antiferromagnetic rare-earth orthoferrite drives behaviour that mimics the application of a magnetic field.

    • T. F. Nova
    • , A. Cartella
    • , A. Cantaluppi
    • , M. Först
    • , D. Bossini
    • , R. V. Mikhaylovskiy
    • , A. V. Kimel
    • , R. Merlin
    •  & A. Cavalleri
  • Letter |

    Drawing microscopic information out of the diffusive dynamics of complex processes often requires an assumption of ergodicity. Precision experiments on a single atom in a periodic potential suggest that this may be too simplistic in many cases.

    • Farina Kindermann
    • , Andreas Dechant
    • , Michael Hohmann
    • , Tobias Lausch
    • , Daniel Mayer
    • , Felix Schmidt
    • , Eric Lutz
    •  & Artur Widera
  • Letter |

    Critical phenomena are well understood in a wide range of physical systems. The dynamics of snap-through instabilities, a widespread phenomenon in their own right, are now shown to display critical scaling properties.

    • Michael Gomez
    • , Derek E. Moulton
    •  & Dominic Vella

Articles

  • Article |

    Superconducting circuits, coupled to form a ring in which a photonic excitation can circulate between sites, are established as a versatile platform for studying the interplay of strong particle interactions and external fields.

    • P. Roushan
    • , C. Neill
    • , A. Megrant
    • , Y. Chen
    • , R. Babbush
    • , R. Barends
    • , B. Campbell
    • , Z. Chen
    • , B. Chiaro
    • , A. Dunsworth
    • , A. Fowler
    • , E. Jeffrey
    • , J. Kelly
    • , E. Lucero
    • , J. Mutus
    • , P. J. J. O’Malley
    • , M. Neeley
    • , C. Quintana
    • , D. Sank
    • , A. Vainsencher
    • , J. Wenner
    • , T. White
    • , E. Kapit
    • , H. Neven
    •  & J. Martinis
  • Article |

    The central densities of protons and neutrons in stable atomic nuclei are saturated. More exotic nuclei — with imbalanced proton and neutron numbers — may have depleted central densities. Experiments now suggest such depletion for the 34Si nucleus.

    • A. Mutschler
    • , A. Lemasson
    • , O. Sorlin
    • , D. Bazin
    • , C. Borcea
    • , R. Borcea
    • , Z. Dombrádi
    • , J.-P. Ebran
    • , A. Gade
    • , H. Iwasaki
    • , E. Khan
    • , A. Lepailleur
    • , F. Recchia
    • , T. Roger
    • , F. Rotaru
    • , D. Sohler
    • , M. Stanoiu
    • , S. R. Stroberg
    • , J. A. Tostevin
    • , M. Vandebrouck
    • , D. Weisshaar
    •  & K. Wimmer
  • Article |

    A detailed and systematic neutron scattering study uncovers a spiral spin-liquid state in the quantum magnet MnSc2S4.

    • Shang Gao
    • , Oksana Zaharko
    • , Vladimir Tsurkan
    • , Yixi Su
    • , Jonathan S. White
    • , Gregory S. Tucker
    • , Bertrand Roessli
    • , Frederic Bourdarot
    • , Romain Sibille
    • , Dmitry Chernyshov
    • , Tom Fennell
    • , Alois Loidl
    •  & Christian Rüegg
  • Article |

    Experiments show that when driven by electric currents, magnetic skyrmions experience transverse motion due to their topological charge — similar to the conventional Hall effect experienced by charged particles in a perpendicular magnetic field.

    • Wanjun Jiang
    • , Xichao Zhang
    • , Guoqiang Yu
    • , Wei Zhang
    • , Xiao Wang
    • , M. Benjamin Jungfleisch
    • , John E. Pearson
    • , Xuemei Cheng
    • , Olle Heinonen
    • , Kang L. Wang
    • , Yan Zhou
    • , Axel Hoffmann
    •  & Suzanne G. E. te Velthuis
  • Article |

    Experiments show that when driven by electric currents, magnetic skyrmions experience transverse motion due to their topological charge — similar to the conventional Hall effect experienced by charged particles in a perpendicular magnetic field.

    • Kai Litzius
    • , Ivan Lemesh
    • , Benjamin Krüger
    • , Pedram Bassirian
    • , Lucas Caretta
    • , Kornel Richter
    • , Felix Büttner
    • , Koji Sato
    • , Oleg A. Tretiakov
    • , Johannes Förster
    • , Robert M. Reeve
    • , Markus Weigand
    • , Iuliia Bykova
    • , Hermann Stoll
    • , Gisela Schütz
    • , Geoffrey S. D. Beach
    •  & Mathias Kläui
  • Article |

    Experiments show how molecular structure affects the interaction and dynamics of the triplet exciton pairs produced when an excited singlet exciton decays via singlet fission — a process that could be harnessed for optoelectronic applications.

    • Leah R. Weiss
    • , Sam L. Bayliss
    • , Felix Kraffert
    • , Karl J. Thorley
    • , John E. Anthony
    • , Robert Bittl
    • , Richard H. Friend
    • , Akshay Rao
    • , Neil C. Greenham
    •  & Jan Behrends
  • Article |

    Experiments show how molecular structure affects the interaction and dynamics of the triplet exciton pairs produced when an excited singlet exciton decays via singlet fission — a process that could be harnessed for optoelectronic applications.

    • Murad J. Y. Tayebjee
    • , Samuel N. Sanders
    • , Elango Kumarasamy
    • , Luis M. Campos
    • , Matthew Y. Sfeir
    •  & Dane R. McCamey
  • Article |

    The triple point is a well-known feature on pressure–temperature phase diagrams. A multiferroic triple point is now reported for La-doped BiFeO3; La concentration and temperature are the phase variables and the phases display different spin (dis)order.

    • Byung-Kweon Jang
    • , Jin Hong Lee
    • , Kanghyun Chu
    • , Pankaj Sharma
    • , Gi-Yeop Kim
    • , Kyung-Tae Ko
    • , Kwang-Eun Kim
    • , Yong-Jin Kim
    • , Kyungrok Kang
    • , Han-Byul Jang
    • , Hoyoung Jang
    • , Min Hwa Jung
    • , Kyung Song
    • , Tae Yeong Koo
    • , Si-Young Choi
    • , Jan Seidel
    • , Yoon Hee Jeong
    • , Hendrik Ohldag
    • , Jun-Sik Lee
    •  & Chan-Ho Yang

Measure for Measure

  • Measure for Measure |

    Klaus von Klitzing tells the story of the quantum Hall effect's impact on metrology.

    • Klaus von Klitzing