Observation of geometric scaling of Efimov states in a Fermi-Bose Li-Cs mixture

Observation of geometric scaling of Efimov states in a Fermi-Bose Li-Cs mixture

Shih-Kuang Tung, Karina Jimenez-Garcia, Jacob Johansen, Colin V. Parker, Cheng Chin

(Submitted on 24 Feb 2014)

The emergence of scaling symmetry in physical phenomena suggests a universal description that is insensitive to microscopic details. A well known example is critical phenomena, which are invariant under continuous scale transformations and classify second-order phase transitions into distinct universality classes. Equally intriguing are systems with discrete scaling symmetry, which are invariant under scaling transformation with a specific scaling constant, resulting in log-periodic behavior in the observables. A classic example is the self-similar growth of crystals, as in snowflakes. In few-body physics, Vitaly Efimov predicted in 1970 the existence of an infinite series of three-body bound states that obey universal discrete scaling symmetry when pair-wise interactions are resonantly enhanced. Despite abundant reports of Efimov states in cold atom experiments, direct observation of discrete scaling symmetry remains an elusive goal. Here we report the observation of three Efimov resonances in a heteronuclear Li-Cs mixture near a broad interspecies Feshbach resonance. The positions of the resonances provide a model-independent confirmation of discrete scaling symmetry with an averaged scaling constant λexp=4.85(44), in good agreement with the predicted value of 4.88. Our findings also provide new insight into the possible discrete scaling symmetry in Bose gasses and mixtures with resonant interactions.

http://arxiv.org/abs/1402.5943