A Research Of Photoelectricity Characteristic In Coupled Quantum Dots And Current Self-oscillation In Superlattices

In this dissertation, several dynamics of electrons in quantum dots system and cur-rent self-oscillation in superlattices are studied in theory. Three models of quantum dots(QDs), including conditional photon-assisted transports(PATs), two coupled PATs, correlation dynamics of photon excited and tunneling are established and explored by means of master equation. Self-oscillation of current in superlattices is also investigated in this thesis.Firstly, a conditionally controlled PAT is theoretically studied in chapter2. A dou-ble QD forms PAT channel and another QD, which act as a conditional one, is residant near by the DQD. Based on a real three-QD model, the two-electron level configuration needed for the conditional photon-assisted transport is designed. Conditional dynam-ics are demonstrated by PAT’s spectrum. Due to various conditional frequencies, the conditional behaviors can be manifested as the current peaks or dips of the PAT. They correspond to coherent excitations or trapping of double-electron states. It presents a possible way to optically manipulate electron states, and to monitor them via the signals of current spectrum.Secondly, the interaction between two photon-assisted transports is theoretically studied in chapter3. Double PATs’ channels are constructed by four quantum dots. Two quantum dots whose energy is at the top of different channel, are coupled together with tunneling. The current spectra are obtained by numerical solution of the master equation. The prominent feature of the tunneling current spectra is two couples of cross current peak lines with several gaps. Those peaks and gaps correspond one channel in resonant exciting and two, respectively. This current is similar to the classic bridge circuit one and can be used in nanoelectrics.Whereafter, correlation dynamics of two electrons in double-double quantum dots system is investigated in chapter4. Rabi oscillation in a double quantum dot (DQD) is coupled with quantum tunneling in another DQD by Coulomb interaction of the neigh-boring dots. Such a coupling leads to correlation of the Rabi oscillating electron and the quantum tunneling one, and gives a tendency to synchronize their transition under ap-propriate Rabi frequency ΩR and tunneling rate Tc. The correlated oscillation is shown in the tunneling current. As ΩR=Tc, the Rabi oscillation and the quantum tunneling reach their strongest correlation and two electrons complete their transitions simultane-ously. And then, a single optical signal accomplishes a gang control of two electrons. The result promotes superior design of two-qubit quantum gates based on correlated DQDs. Finally, current self-Oscillation in superlattices is explored in chapter5. Solving differential equation of full currents with a double Lorentz drift velocity model, the oscillation frequencies and irradiation power are obtained. The method to enhance the oscillation frequencies and the irradiation power are also given.