Noise spectrum of charge current in a quantum dot system under the irradiation of quantum electromagnetic field

• The noise spectrum of a quantum dot perturbed by a quantum electromagnetic field (QEMF) is investigated.
• The current correlation induced by the SU(1,1)SU(1,1) coherent state of QEMF play an important role.
• The stair-like and photon-assisted behaviors are obviously exhibited.
• The enhancement and suppression of noise can be controlled by adjusting the parameters.

We have investigated the noise spectrum of a quantum dot (QD) coupled to two normal metal leads under the perturbation of a quantum electromagnetic field (QEMF) by nonequilibrium Greenʼs function method. Current correlation function is determined through making the ensemble average over the lowest SU(1,1)SU(1,1) coherent state. The fluctuation of QEMF makes important contribution to the noise by imposing an additional term, and quantum feature of the QEMF is transferred to the shot noise. The total noise of our system is composed of three parts: the thermal noise, the quantum field noise, and the shot noise. The quantum field noise is generated from the QEMF, and it dominates the total noise. The shot noise and quantum field noise belong to different types, and they display quite differently. The stair-like and photon-assisted behaviors are obviously exhibited. The enhancement and suppression of noise can be controlled by adjusting the parameters according to its behaviors.