Probing pseudogap by Josephson tunneling

We propose here an experiment aimed to determine whether there are superconducting pairing fluctuations in the pseudogap regime of the high-T{sub c} materials. In the experimental setup, two samples above T{sub c} are brought into contact at a single point and the differential ac conductivity in the presence of a constant applied bias voltage between the samples, V, should be measured. We argue that the pairing fluctuations will produce randomly fluctuating Josephson current with zero mean, however, the current-current correlator will have a characteristic frequency given by Josephson frequency {omega}{sub J}=2eV/({Dirac_h}/2{pi}). We predict that the differential ac conductivity and the Josephson microwave radiation should have peaks at the Josephson frequency with the width determined by the phase fluctuations time. (c) 2000 The American Physical Society.