Quantum Transports In A Quantum Dot Driven By Stochastic Fields

Quantum dot also known as "artificial atoms", which has some basic features of atomic physics. But compared to the atom it has greater maneuverability, such as through the quantum dot size, chemical composition and temperature can regulate the size of the energy gap, luminous bands. At the same time, quantum dots based on their unique properties, with many obvious quantum effects, such as due to the quantum size effect caused by the discrete nature of the quantum dot electronic level; due to the three dimensional confinement leads to the quantum confinement effect, and due to the fluctuation of particle caused by the macroscopic quantum tunneling effect and so on.A variety of special properties of quantum dot makes it have a wide range of applications since it was discovered.Such as in the device, quantum dots can applied to the QD lasers,QD infrared detectors and so on; in the biomedicine filed, quantum dot can be used for biological markers, as a fluorescent probe and so on. And based on the quantum dot transport properties, and has been the focus of research. The electron transport properties of the quantum dot has been discovered, including sequential tunneling effect,Coulomb blockade effect, Kondo effect, Fano effect and the Aharonov-Bohm effect. But all along, in the study of the quantum dot transport properties, people always consider the intensity of the light field as a fixed value, and in reality, the intensity of the light field will have a certain fluctuation. Therefore, in this paper, we investigate the electronic transport properties of quantum dot under the control of random light field.The main contents are as follows:(1) In this paper, we introduce the research results of quantum dot at this stage,and summarize the transport properties of the quantum dots which have already been discovered. It is well known that in the quantum dot, it can only be observed in the nonequilibrium environment(for example, in this paper, we applied bias voltage to the system). Shot noise can provide those information that conductivity measurements are missing in the transport process, including the ability to get in some statistical properties of the carrier electron transport through a quantum dot; can be used to determine the transfer charge units; can obtain some information about the internal structure and so on.On the other hand, we can modulate the amplitude of the shot noise by the correlation of the electron in the transport process.(2) A two level quantum dot system driven by coherent fields is set up, which is controlled by the light field. It is assumed that the correlation function between the quantum dot and the random field satisfies the Gaussian-Markovian stochastic process,its mean value is zero, and the correlation function satisfies||)()(tttxteDx--???????.Among them, D is the intensity of the airport and?is dependent on the amount of bandwidth associated with the filed.(3) The main equation and the rate equation of the system are derived from the Hamiltonian, and the current and shot noise in the system are studied theoretically. In mesoscopic systems under a large bias, the rate equation approach at the outset covers the inelastic scattering, charge interactions and coupling with the outside world and other issues; at the same time it is not only capable of handling a lot of problems to resolve, but also simpler than other methods and easier to understand. In this paper, we use the rate equation method to describe the electron transport in the system.(4) In the results and discussion, we find that the introduction of the random field can enhance the resonance effect of the quantum dot and the coherent field of resonance effects, and introducing a new resonance point. At the resonance point, the difference between the number of the two energy levels in the quantum dot is suppressed, and the current is greatly enhanced. At the same time, the zero frequency shot noise of current can be transformed into the random field with the proper modulation of the airport. At the same time, the zero-frequency noise current shot through with the appropriate modulation airport can be drastically transformed between the sub and super Poisson Poisson.