We propose here an experiment aimed to determine whether there are superconducting pairing fluctuations in the pseudogap regime of the high-$T_c$ materials. In the experimental setup, two samples above $T_c$ 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 ${\omega }_J=2eV/ħ.$ 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.

• Received 3 February 2000

DOI:https://doi.org/10.1103/PhysRevB.62.R6124