摘要: Critical phenomena emerge when a many-body system is in the proximity of a continuous phase transition. Quantum criticality, in particular, anticipates universal properties of a system near a transition driven by quantum fluctuations at low temperatures, providing the key to understanding many diverse natural systems ranging from subatomic particles to black holes in the universe. Ultracold atoms offer a clean system to test these predicted universal properties. In this talk, I will share our recent observation of quantum criticality with two-dimensional Bose gases in optical lattices. On the basis of in situ density measurements, we observe scaling behavior of the equation of state at low temperatures, locate the quantum critical point, and constrain the critical exponents. Our method holds promise for identifying general quantum phase transitions and for studying how critical systems evolve over time. In addition, I will briefly discuss our recent upgrade of imaging setup for higher resolution with a custom-designed microscope objective.

Reference:Observation of quantum criticality with ultracold atoms in optical lattices. X. Zhang, C.-L. Hung, S.-K. Tung, and C.Chin, Science 335, 1070-1072 (2012).