  We report first-order spatial and temporal correlations in strongly coupled
plasmonic Bose-Einstein condensates. The condensate is large, more than twenty
times the intrinsic spatial coherence length of the polaritons and hundred
times the healing length, making plasmonic lattices an attractive platform for
studying long-range spatial correlations in two dimensions. We find that both
spatial and temporal coherence display non-exponential decay; the results
suggest power-law or stretched exponential behaviour with different exponents
for spatial and temporal correlation decays.
