Acoustic tractor beam

Christine E. M. Demore, Patrick M. Dahl, Zhengyi Yang, Peter Glynne-Jones, Andreas Melzer, Sandy Cochran, Michael P. MacDonald (Lead / Corresponding author), Gabriel C. Spalding (Lead / Corresponding author)

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77 Citations (Scopus)
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Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (> 1 cm) to demonstrate the negative radiation forces, and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to non-conservative forces, produced by redirection of a momentum flux from the angled sides of a target, and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams, and demonstrates continuous attraction towards the source, against a net momentum flux in the system.
Original languageEnglish
Article number174302
Number of pages5
JournalPhysical Review Letters
Issue number17
Publication statusPublished - 30 Apr 2014


  • acoustic tweezing
  • negative radiation force
  • Tractor beam

ASJC Scopus subject areas

  • Acoustics and Ultrasonics


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