Imaging Quantum states of Bosonic atoms @ University of Chicago

Author(s):

Nathan Gemelke, Xibo Zhang, Chen-Lung Hung, Cheng Chin

By tuning the optical lattice depth or the interaction between cold atoms, a weakly-interacting atomic bosonic superfluid can be converted into a strongly correlated Mott insulator. Near the phase boundary, quantum criticality, resembling that of Ising-type magnetic systems in higher dimensions, is expected to emerge with full universal behavior. Cold atom researchers in IRG4 have established the first in situ imaging for bosonic atoms in 2D optical lattices, which provides a powerful tool to capture the full quantum state of the many-body system, from the microscopic statistics of site occupancy to the macroscopic thermodynamics. This experimental milestone has also been achieved along with very interesting findings: observation of the long- sought plateau structure of the Mott insulator, and the incompressibility of the Mott insulator domains. New experiments to explore the quantum dynamics of atoms in the quantum critical regime have shown interesting transport behavior in mass and entropy flows. In particular, time scales very different from microsopic tunneling and interaction time scales have been identified in the global equilibration of the 2D system.

Related publication(s):

1. "In situ Observation of incompressible Mott-insulating domains in ultracold atomic gases," Nathan Gemelke, Xibo Zhang, Chen-Lung Hung, Cheng Chin, Nature 460, 995 (2009).