Quasiparticle Energy in a Strongly Interacting Homogeneous Bose-Einstein Condensate

Raphael Lopes, Christoph Eigen, Adam Barker, Konrad G. H. Viebahn, Martin Robert-de-Saint-Vincent, Nir Navon, Zoran Hadzibabic, and Robert P. Smith
Phys. Rev. Lett. 118, 210401 – Published 23 May 2017

Abstract

Using two-photon Bragg spectroscopy, we study the energy of particlelike excitations in a strongly interacting homogeneous Bose-Einstein condensate, and observe dramatic deviations from Bogoliubov theory. In particular, at large scattering length a the shift of the excitation resonance from the free-particle energy changes sign from positive to negative. For an excitation with wave number q, this sign change occurs at a4/(πq), in agreement with the Feynman energy relation and the static structure factor expressed in terms of the two-body contact. For a3/q we also see a breakdown of this theory, and better agreement with calculations based on the Wilson operator product expansion. Neither theory explains our observations across all interaction regimes, inviting further theoretical efforts.

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  • Received 13 February 2017

DOI:https://doi.org/10.1103/PhysRevLett.118.210401

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & OpticalCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Raphael Lopes*, Christoph Eigen, Adam Barker, Konrad G. H. Viebahn, Martin Robert-de-Saint-Vincent, Nir Navon, Zoran Hadzibabic, and Robert P. Smith

  • Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom

  • *rl531@cam.ac.uk
  • Present address: Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom.
  • Present address: Laboratoire de Physique des Lasers, CNRS UMR 7538, Université Paris 13, Sorbonne Paris Cité, F-93430 Villetaneuse, France.

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Issue

Vol. 118, Iss. 21 — 26 May 2017

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