Volume 15 Issue 12, December 2019

Volume 15 Issue 12

Magnetic collapse

Spin-polarized tunnelling data show that the breakdown of antiferromagnetic order and the collapse of the spectral gap are not correlated in Sr2IrO4. This indicates that short-range magnetic correlations are not behind the emergence of the pseudogap.

See Zeljkovic et al.

Image: He Zhao and Ilija Zeljkovic, Boston College. Cover Design: David Shand

Editorial

Thesis

Books & Arts

Research Highlights

News & Views

  • News & Views |

    High-magnetic-field experiments on the recently discovered unconventional superconductor UTe2 are consistent with p-wave pairing arising while time-reversal symmetry is broken. In turn, this suggests that this material is a candidate for a chiral superconductor that may be exploited for topological quantum computing.

    • Marc Janoschek
  • News & Views |

    An unusual flavour of critical phenomena with a stable quantum critical phase of matter is observed in a strongly correlated material and linked to the underlying lattice structure.

    • Aline Ramires
  • News & Views |

    Non-Hermitian systems with gain and loss give rise to exceptional points with exceptional properties. An experiment with superconducting qubits now offers a first step towards studying these singularities in the quantum domain.

    • Stefan Rotter

Perspectives

  • Perspective |

    This Perspective argues that ergodicity — a foundational concept in equilibrium statistical physics — is wrongly assumed in much of the quantitative economics literature. By asking the extent to which dynamical problems can be replaced by probabilistic ones, many economics puzzles are resolved in a natural and empirically testable fashion.

    • Ole Peters

Letters

  • Letter |

    Experiments with two counter-propagating laser beams report the observation that the photon momentum is shared between the electron and parent ion in strong-field ionization, which results from the photon’s magnetic field acting on the electron.

    • A. Hartung
    • , S. Eckart
    • , S. Brennecke
    • , J. Rist
    • , D. Trabert
    • , K. Fehre
    • , M. Richter
    • , H. Sann
    • , S. Zeller
    • , K. Henrichs
    • , G. Kastirke
    • , J. Hoehl
    • , A. Kalinin
    • , M. S. Schöffler
    • , T. Jahnke
    • , L. Ph. H. Schmidt
    • , M. Lein
    • , M. Kunitski
    •  & R. Dörner
  • Letter |

    The Kibble–Zurek mechanism, that is, the spontaneous formation of topological defects in a system crossing a continuous phase transition, is observed in a strongly interacting Fermi gas, where the underlying symmetry plays a crucial role.

    • Bumsuk Ko
    • , Jee Woo Park
    •  & Y. Shin
  • Letter |

    Conventional on-axis electron energy-loss spectroscopy can detect vibrational modes in crystals and amorphous solids at atomic resolution by isolating the specific signal from the background signal and the dipole contributions.

    • Kartik Venkatraman
    • , Barnaby D. A. Levin
    • , Katia March
    • , Peter Rez
    •  & Peter A. Crozier
  • Letter |

    Matter-wave interference experiments demonstrate quantum superposition of molecules consisting of up to 2,000 atoms—the heaviest objects to show this quantum behaviour to date. This provides a bound on potential modifications to quantum mechanics.

    • Yaakov Y. Fein
    • , Philipp Geyer
    • , Patrick Zwick
    • , Filip Kiałka
    • , Sebastian Pedalino
    • , Marcel Mayor
    • , Stefan Gerlich
    •  & Markus Arndt
  • Letter |

    The predicted metallization of hydrogen has long fascinated high-pressure physicists. Conductivity and spectroscopic measurements now reveal that above pressures of 350 GPa, hydrogen starts to conduct in a manner akin to a semimetal.

    • M. I. Eremets
    • , A. P. Drozdov
    • , P. P. Kong
    •  & H. Wang
  • Letter |

    The recently discovered spin-triplet superconductor UTe2 is found to display a number of other ‘re-entrant’ superconducting phases under ultrahigh magnetic fields.

    • Sheng Ran
    • , I-Lin Liu
    • , Yun Suk Eo
    • , Daniel J. Campbell
    • , Paul M. Neves
    • , Wesley T. Fuhrman
    • , Shanta R. Saha
    • , Christopher Eckberg
    • , Hyunsoo Kim
    • , David Graf
    • , Fedor Balakirev
    • , John Singleton
    • , Johnpierre Paglione
    •  & Nicholas P. Butch
  • Letter |

    Few-layer magnetic materials sometimes show a different form of magnetism from their thicker equivalents. The authors contend that the mechanism is changes in the stacking order in the thin limit that modify the interlayer exchange interaction.

    • Dahlia R. Klein
    • , David MacNeill
    • , Qian Song
    • , Daniel T. Larson
    • , Shiang Fang
    • , Mingyu Xu
    • , R. A. Ribeiro
    • , P. C. Canfield
    • , Efthimios Kaxiras
    • , Riccardo Comin
    •  & Pablo Jarillo-Herrero
  • Letter |

    A phase of quantum-critical behaviour is observed in a kagome lattice material. This arises from the interplay of strong interactions between electrons, and the frustration that arises both from the interactions and the lattice geometry.

    • Hengcan Zhao
    • , Jiahao Zhang
    • , Meng Lyu
    • , Sebastian Bachus
    • , Yoshifumi Tokiwa
    • , Philipp Gegenwart
    • , Shuai Zhang
    • , Jinguang Cheng
    • , Yi-feng Yang
    • , Genfu Chen
    • , Yosikazu Isikawa
    • , Qimiao Si
    • , Frank Steglich
    •  & Peijie Sun
  • Letter |

    Spin-polarized tunnelling data show that the breakdown of antiferromagnetic order and the collapse of the spectral gap are not correlated in Sr2IrO4. This indicates that short-range magnetic correlations are not behind the emergence of the pseudogap.

    • He Zhao
    • , Sujit Manna
    • , Zach Porter
    • , Xiang Chen
    • , Andrew Uzdejczyk
    • , Jagadeesh Moodera
    • , Ziqiang Wang
    • , Stephen D. Wilson
    •  & Ilija Zeljkovic

Articles

  • Article |

    A quantum circuit-based algorithm inspired by convolutional neural networks is shown to successfully perform quantum phase recognition and devise quantum error correcting codes when applied to arbitrary input quantum states.

    • Iris Cong
    • , Soonwon Choi
    •  & Mikhail D. Lukin
  • Article |

    X-ray pump–probe experiments reveal that the molecular structure of C60 molecules substantially delays their fragmentation following photoionization. This may help to understand X-ray laser-induced radiation damage on molecules.

    • N. Berrah
    • , A. Sanchez-Gonzalez
    • , Z. Jurek
    • , R. Obaid
    • , H. Xiong
    • , R. J. Squibb
    • , T. Osipov
    • , A. Lutman
    • , L. Fang
    • , T. Barillot
    • , J. D. Bozek
    • , J. Cryan
    • , T. J. A. Wolf
    • , D. Rolles
    • , R. Coffee
    • , K. Schnorr
    • , S. Augustin
    • , H. Fukuzawa
    • , K. Motomura
    • , N. Niebuhr
    • , L. J. Frasinski
    • , R. Feifel
    • , C. P. Schulz
    • , K. Toyota
    • , S.-K. Son
    • , K. Ueda
    • , T. Pfeifer
    • , J. P. Marangos
    •  & R. Santra
  • Article |

    Vacuum fluctuations in the vicinity of nanophotonic structures can lead to the conversion of a free electron into a polariton and a high-energy photon, whose frequency can be controlled by the electromagnetic properties of the nanostructure.

    • Nicholas Rivera
    • , Liang Jie Wong
    • , John D. Joannopoulos
    • , Marin Soljačić
    •  & Ido Kaminer
  • Article |

    The remarkably large thermal Hall response recently observed in the copper oxides challenges our understanding of the excitations in an insulating antiferromagnet. Here, a possible explanation of the underlying physics is provided.

    • Rhine Samajdar
    • , Mathias S. Scheurer
    • , Shubhayu Chatterjee
    • , Haoyu Guo
    • , Cenke Xu
    •  & Subir Sachdev
  • Article |

    In a model system crosslinked by motors, cytoskeletal polymers slide past each other at speeds independent of their polarity. This behaviour is best described within an active-gel framework that deviates from the dilute limit set by existing theory.

    • Sebastian Fürthauer
    • , Bezia Lemma
    • , Peter J. Foster
    • , Stephanie C. Ems-McClung
    • , Che-Hang Yu
    • , Claire E. Walczak
    • , Zvonimir Dogic
    • , Daniel J. Needleman
    •  & Michael J. Shelley

Amendments & Corrections

Measure for Measure

  • Measure for Measure |

    Tell Bartolo Luque and Fernando Ballesteros how far the Sun is from the Earth, and they will tell you the size of the Universe.

    • Bartolo Luque
    •  & Fernando J. Ballesteros