2016/08/31 by Jiaming Li, Andrew K. Harter, Ji Liu +3 · 3 citations
Physics and Astronomy · #cond-mat.quant-gas #physics.atom-ph #quant-ph
paper · pdf · doi:10.1038/s41467-019-08596-1
published as Nature Communications, volume 10, Article number: 855 (2019) · 23 pages, 4 figures, 39 references
arxiv created 2019/01/30 · arxiv updated 2019/02/27
Open physical systems with balanced loss and gain, described by non-Hermitian parity-time (PT) reflection symmetric Hamiltonians, exhibit a transition which could engenders modes that exponentially decay or grow with time and thus spontaneously breaks the PT-symmetry. Such PT-symmetry breaking transitions have attracted many interests because of their extraordinary behaviors and functionalities absent in closed systems. Here we report on the observation of PT-symmetry breaking transitions by engineering time-periodic dissipation and coupling, which are realized through state-dependent atom loss in an optical dipole trap of ultracold 6Li atoms. Comparing with a single transition appearing for static dissipation, the time-periodic counterpart undergoes PT-symmetry breaking and restoring transitions at vanishingly small dissipation strength in both single and multiphoton transition domains, revealing rich phase structures associated to a Floquet open system. The results enable ultracold atoms to be a versatile tool for studying PT-symmetric quantum systems.