2020/11/30 by Thomas G. Skov, Magnus G. Skou, Nils B. Jørgensen +2 · 79 citations
Physics and Astronomy · #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #Computer science #Physics #Quantum, superfluid, helium dynamics #Statistical physics #Theoretical physics #cond-mat.quant-gas #physics.atom-ph
paper · pdf · open access · doi:10.1103/physrevlett.126.230404
published in Physical Review Letters 126(23), 230404 (American Physical Society) · 8 pages, 6 figures
openalex publication_date 2021/06/11 · arxiv created 2021/06/16 · arxiv updated 2021/06/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We observe monopole oscillations in a mixture of Bose-Einstein condensates, where the usually dominant mean-field interactions are canceled. In this case, the system is governed by the next-order Lee-Huang-Yang (LHY) correction to the ground state energy, which describes the effect of quantum fluctuations. Experimentally such a LHY fluid is realized by controlling the atom numbers and interaction strengths in a 39K spin mixture confined in a spherical trap potential. We measure the monopole oscillation frequency as a function of the LHY interaction strength as proposed recently by Jrgensen et al. [Phys. Rev. Lett. 121, 173403 (2018)PRLTAO0031-900710.1103/PhysRevLett.121.173403] and find excellent agreement with simulations of the complete experiment including the excitation procedure and inelastic losses. This confirms that the system and its collective behavior are initially dominated by LHY interactions. Moreover, the monopole oscillation frequency is found to be stable against variations of the involved scattering lengths in a broad region around the ideal values, confirming the stabilizing effect of the LHY interaction. These results pave the way for using the nonlinearity provided by the LHY term in quantum simulation experiments and for investigations beyond the LHY regime.