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Volume 16 Issue 3, March 2020

Volume 16 Issue 3

Oddly synchronised

An experiment with three alternating-current generators demonstrates converse symmetry breaking — a phenomenon whereby the system achieves frequency synchronization when its component systems are tuned asymmetrically.

See Nishikawa et al.

Image: Ferenc Molnar, University of Notre Dame; Takashi Nishikawa and Adilson E. Motter, Northwestern University. Cover Design: David Shand


  • Editorial |

    The combination of microwave photons with superconducting quantum circuits offers promise for quantum technologies and the fundamental study of quantum light–matter interactions. This month, a Focus issue explores this field of research.



  • Comment |

    In 1985, experiments revealed the quantum behaviour of a macroscopic degree of freedom: the phase difference across a Josephson junction. The authors recount the history of this milestone for the development of superconducting quantum circuits.

    • John M. Martinis
    • Michel H. Devoret
    • John Clarke



Books & Arts

  • Books & Arts |

    • Christine-Maria Horejs

Research Highlights

News & Views

  • News & Views |

    Speed is of the essence when it comes to signal processing, but electronic switching times have reached a limit. Optically controlled tunnel currents across a nanoscale plasmonic gap could considerably accelerate future nanoelectronic devices.

    • Olga Smirnova


  • Perspective |

    This article puts in perspective the relationship between cavity and circuit quantum electrodynamics, two related approaches for studying the fundamental quantum interaction between light and matter.

    • S. Haroche
    • M. Brune
    • J. M. Raimond


Review Articles

  • Review Article |

    Hybrid quantum systems combine heterogeneous physical systems for the implementation of new functionalities at the quantum level. This article reviews recent research on the creation of hybrid quantum systems within the circuit quantum electrodynamics framework.

    • A. A. Clerk
    • K. W. Lehnert
    • Y. Nakamura




  • Article |

    The variational quantum unsampling protocol provides a way to realize verification and inference of near-term quantum circuit outputs. This protocol is then experimentally verified on a quantum photonic processor.

    • Jacques Carolan
    • Masoud Mohseni
    • Dirk Englund
  • Article |

    Following an impulsive laser excitation of a single molecule, a dispersed vibrational wave-packet is partially rephased by a second pulse, and a wave-packet echo is observed. This wave-packet echo probes ultrafast intramolecular processes in the isolated molecule.

    • Junjie Qiang
    • Ilia Tutunnikov
    • Jian Wu
  • Article |

    Single-cycle interferometric autocorrelation measurements of electrons tunnelling across the gap of a plasmonic bowtie antenna and quantitative models provide insight into the physical interactions that drive the electron transfer.

    • Markus Ludwig
    • Garikoitz Aguirregabiria
    • Daniele Brida
  • Article |

    An experiment with three alternating-current generators demonstrates converse symmetry breaking—a phenomenon whereby the system achieves frequency synchronization when its component systems are tuned asymmetrically.

    • Ferenc Molnar
    • Takashi Nishikawa
    • Adilson E. Motter
  • Article |

    A detailed theoretical and experimental investigation of homogeneous cell tissues finds that they can undergo spontaneous spatial symmetry breaking through a purely electrophysiological mechanism.

    • Harold M. McNamara
    • Rajath Salegame
    • Adam E. Cohen

Amendments & Corrections

Measure for Measure

  • Measure for Measure |

    Philip Lössl tells of mass spectrometry’s struggles to come to terms with terminology.

    • Philip Lössl


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