Artificial trapping of a stable high-density dipolar exciton fluid
  We present compelling experimental evidence for a successful electrostatic trapping of two-dimensional dipolar excitons that results in stable formation of a well confined, high-density and spatially uniform dipolar exciton fluid. We show that, for at least half a microsecond, the exciton fluid sustains a density higher than the critical density for degeneracy if the exciton fluid temperature reaches the lattice temperature within that time. This method should allow for the study of strongly interacting bosons in two dimensions at low temperatures, and possibly lead towards the observation of quantum phase transitions of 2D interacting excitons, such as superfluidity and crystallization. 
Gang Chen, Ronen Rapaport, L. N. Pffeifer, K. West, P. M. Platzman,   Steven Simon, Z. Voros, and D. Snoke