Probing the Bose-Glass---Superfluid Phase Boundary using Quantum Quenches of Disorder in an Optical Lattice

We detect the phase boundary between superfluid (SF) and Bose-glass (BG) states in the disordered Bose Hubbard model using quantum quenches of disorder in an optical lattice. ~The BG phase has not been directly detected in experiments, and there are numerous questions regarding how temperature, density, and an inhomogeneous trap affect the BG---SF transition. ~We use ultracold Rubidium-87 trapped atoms in a disordered optical lattice generated using an optical speckle field to realize the disordered Bose Hubbard model. ~By rapidly quenching the disorder, we detect the BG---SF transition by measuring excitations produced by the quantum Kibble-Zurek mechanism.