2019/10/31 by Jian-Song Pan, W. Vincent Liu, Xiong-Jun Liu
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Degenerate energy levels #Goldstone boson #Lattice (music) #Mathematical physics #Mechanical and Optical Resonators #Noncommutative geometry #Physics #Position and momentum space #Quantum mechanics #Spontaneous symmetry breaking #Superfluidity #Symmetry breaking #Theoretical physics #Topological Materials and Phenomena #Topology (electrical circuits) #Type (biology) #cond-mat.quant-gas #hep-th #quant-ph
paper · pdf · doi:10.1103/physrevlett.125.260402
published as Phys. Rev. Lett. 125, 260402 (2020) · 5+9 pages, 4 figures
arxiv created 2020/12/23 · openalex publication_date 2020/12/23 · arxiv updated 2020/12/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The Nambu-Goldstone (NG) modes in a nonrelativistic system can be classified into two types from their characteristic features: being of either an odd (type I) or an even (type II) power energy-momentum dispersion. Conventionally, the type-II NG modes may universally arise from spontaneous breaking of noncommutative symmetry pairs. Here, we predict a novel type of quadratically dispersed NG modes that emerges in mixed s and p band Bose superfluids in an optical lattice and, unlike the conventional type-II NG modes, cannot be solely interpreted with the celebrated symmetry-based argument. Instead, we show that the existence of such modes has a profound connection to the topological transition on projective complex order-parameter space. The detection scheme is also proposed. Our Letter reveals a new universal mechanism for emergence of type-II NG modes, which bridges intrinsically the Landau symmetry-breaking and topological theories.