Quantum transport modeling of current noise in quantum devices

We have studied the current noise characteristics of quantum devices at low temperature, particularly, a quantum dot and a double barrier resonant tunneling diode (DBRTD). By using the nonequilibrium Green´s function method based on the Keldysh´s perturbation theory, we have found that the suppression of shot noise is observed in DBRTD only around the bias voltage of the resonant tunneling. The noise suppression is found to be maximum at a bias voltage a little lower than the current peak voltage. On the other hand, the shot noise of the quantum dot is always suppressed above the bias voltage where the current starts to flow after overcoming the Coulomb blockade.