2017/09/19 by M. Di Liberto, A. Recati, N. Trivedi +2 · 1 citation
Physics and Astronomy · #cond-mat.quant-gas #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevlett.120.073201
published as Phys. Rev. Lett. 120, 073201 (2018) · 6 pages, 3 figures
arxiv created 2017/09/19 · arxiv updated 2018/02/21
We study the low-energy excitations of the Bose-Hubbard model in the strongly-interacting superfluid phase using a Gutzwiller approach and extract the single-particle and single-hole excitation amplitudes for each mode. We report emergent mode-dependent particle-hole symmetry on specific arc-shaped lines in the phase diagram connecting the well-known Lorentz-invariant limits of the Bose-Hubbard model. By tracking the in-phase particle-hole symmetric oscillations of the order parameter, we provide an answer to the long-standing question about the fate of the pure amplitude Higgs mode away from the integer-density critical point. Furthermore, we point out that out-of-phase oscillations are responsible for a full suppression of the condensate density oscillations of the gapless Goldstone mode. Possible detection protocols are also discussed.