Photon-Assisted Tunneling in a Biased Strongly Correlated Bose Gas
  We study the impact of coherently generated lattice photons on an atomic Mott insulator subjected to a uniform force. Analogous to an array of tunnel-coupled and biased quantum dots, we observe sharp, interaction-shifted photon-assisted tunneling resonances corresponding to tunneling one and two lattice sites either with or against the force, and resolve multiorbital shifts of these resonances. By driving a Landau-Zener sweep across such a resonance, we realize a quantum phase transition between a paramagnet and an antiferromagnet, and observe quench dynamics when the system is tuned to the critical point. Direct extensions will produce gauge fields and site-resolved spin flips, for topological physics and quantum computing. 
Ruichao Ma, M. Eric Tai, Philipp M. Preiss, Waseem S. Bakr, Jonathan   Simon and Markus Greiner
cond-mat.quant-gas quant-ph