Many-body correlations of electrostatically trapped dipolar excitons
  We study the photoluminescence (PL) of a two-dimensional liquid of oriented dipolar excitons in In_{x}Ga_{1-x}As coupled double quantum wells confined to a microtrap. Generating excitons outside the trap and transferring them at lattice temperatures down to T = 240 mK into the trap we create cold quasi-equilibrium bosonic ensembles of some 1000 excitons with thermal de Broglie wavelengths exceeding the excitonic separation. With decreasing temperature and increasing density n <= 5*10^10 cm^{-2} we find an increasingly asymmetric PL lineshape with a sharpening blue edge and a broad red tail which we interpret to reflect correlated behavior mediated by dipolar interactions. From the PL intensity I(E) below the PL maximum at E_{0} we extract at T < 5 K a distinct power law I(E) \sim (E_{0}-E)^-|\alpha| with -|\alpha|\sim -0.8 in the range E_{0}-E of 1.5-4 meV, comparable to the dipolar interaction energy. 
G. J. Schinner, J. Repp, E. Schubert, A. K. Rai, D. Reuter, A. D.   Wieck, A. O. Govorov, A. W. Holleitner, and J. P. Kotthaus
cond-mat.mes-hall