Effect of the Kondo correlation on Shot Noise in a Quantum Dot

The current noise in a quantum dot coupled to two leads is investigated in the Kondo regime with and without the influence of magnetic fields by employing a finite-$U$ slave-boson mean field theory to calculate the current-current correlation function at zero temperature. The numerical results show that, depending on the energy level of the QD the Coulomb interactin may reduce or enhance the zero-frequency shot noise power spectrum in comparison with that without Coulomb interaction. But the Fano factor is always reduced significantly due to the Kondo-correlation effect, and the most pronounced suppression appears at the electron-hole symmetry case $2\epsilon_d+U=0$. In addition, the application of a magnetic field enhance the Fano factor of the shot noise at small external voltage, which is attributed to the reduction of the Kondo-enhanced density-of-state and transmission probability in a quantum dot.