Probing superconducting phase fluctuations from the current noise spectrumof pseudogapped metal-superconductor tunnel junctions

We study the current noise spectra of a tunnel junction of a metal with str ong pairing phase fluctuation and a superconductor. It is shown that there is a characteristic peak in the noise spectrum at the intrinsic Josephson f requency omega(J) = 2eV when omega(J) is smaller than the pairing gap but l arger than the pairing scattering rate. In he presence of an ac voltage, th e tunneling current noise shows a series of characteristic peaks with incre asing de voltage. Experimental observation of these peaks will give direct evidence of the pair fluctuation in the normal state of high-T-c supercondu ctors and the pair decay rate can be estimated from the half width of the p eaks.