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Quasiparticle energy in a strongly interacting homogeneous Bose-Einstein condensate

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 a≈4/(πq), in agreement with the Feynman energy relation and the static structure factor expressed in terms of the two-body contact. For a≳3/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.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1103/physrevlett.118.210401

Authors


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Role:
Author
ORCID:
0000-0003-3877-8478



Publisher:
American Physical Society
Journal:
Physical Review Letters More from this journal
Volume:
118
Issue:
21
Pages:
210401
Publication date:
2017-05-23
Acceptance date:
2017-04-25
DOI:
EISSN:
1079-7114
ISSN:
0031-9007
Pmid:
28598671


Language:
English
Keywords:
Pubs id:
pubs:700128
UUID:
uuid:f9cd31cf-481e-433e-b96e-154eceba11dc
Local pid:
pubs:700128
Source identifiers:
700128
Deposit date:
2018-06-19

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