Exciton condensate at a total filling factor of one in Corbino two-dimensional electron bilayers

Magnetotransport and drag measurements on a quasi-Corbino two-dimensional electron bilayer at a total filling factor of 1 $({\ensuremath{\nu}}_{T}=1)$ reveal a drag voltage that is equal in magnitude to the drive voltage as soon as the two layers begin to form the expected ${\ensuremath{\nu}}_{T}=1$ exciton condensate. The identity of both voltages remains present even at elevated temperatures of $0.25\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The conductance of the drive layer vanishes only in the limit of strong coupling between the two layers and at $T\ensuremath{\rightarrow}0\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ which suggests the presence of an excitonic circular current.