Measurements of correlated conductances and noise fluctuations from 3-lead quantum dots

We have investigated the conductance properties of a few-electron quantum dot with three terminals. In the regime of strong coupling between the quantum dot and the leads, we have observed the both the integer- and half-integer-spin Kondo effect at zero magnetic field. Within the integer-spin conductance diamond, we find cotunneling spectral lines which correspond to singlet-triplet transitions. We extract the exchange energy from this information and find that the value (J = 320 mu eV) agrees remarkably well with the theoretical prediction [7]. We believe that spin dependent transport in a three-terminal quantum dot could yield positive cross-correlations between shot noise events on two output channels. To investigate such phenomena, we have designed an analog continuum cross-correlator to analyze the shot noise spectra of our device in the X- and Ku-bands (8 to 18 GHz).