  We study the dual quark condensate as a signal for the
confinement-deconfinement phase transition of QCD. This order parameter for
center symmetry has been defined recently by Bilgici et al. within the
framework of lattice QCD. In this work we determine the ordinary and the dual
quark condensate with functional methods using a formulation of the
Dyson-Schwinger equations for the quark propagator on a torus. The temperature
dependence of these condensates serves to investigate the interplay between the
chiral and deconfinement transitions of quenched QCD.
