Theory Coupled Double Quantum Dot System Of Transport Properties

In this thesis, we mainly focus on the study of the quantum transport properties of double quantum dots, including spin blockade, orbital blockade, electron spin resonance, resonant tunneling, spin-orbit coupling. In particular, we use these properties to study its applications.Firstly, we introduce the characteristics of quantum dot, dark state in quantum optics and dark state of electron transport. And summarize the main content of our thesis.Secondly, we analyze transport through an asymmetric double quantum dot with inhomogeneous Zeeman splittings in the presence of crossed dc and ac magnetic fields. Due to spin and orbital degrees of freedom play different roles in quantum transport through nanostructures. We study spin and orbital blockade in quantum transport through our system. The interplay among electron spin resonance, Pauli exclusion, resonant tunneling, and quantum interference leads to quite different current responses for forward/backward bias in the slow/fast spin-flip regime. In particular, as change of the dc magnetic field, we observe both spin blockade (due to multiple particle spin correlation) and orbital blockade (due to quantum destructive interference) in the same system. Strong spin-polarized current can be achieved by changing the dc magnetic field. It is mainly due to the resonant tunneling. But for ferromagnetic right electrode, the electron spin resonance also plays an important role in transport. We show that a double quantum dot with three-level mixing under crossed dc and ac magnetic fields can act as bipolar spin filter, sensitive spin switch, and spin inverter under suitable conditions.Finally, we consider that our system contains Rashba spin-orbital coupling due to the asymmetry of the structure. Our calculation method is formulated by second quantizing the spin-orbital interaction in spectral space, and quantum transport is then analyzed with rate equation. We study the influence of Rashba spin-orbital interaction on orbital dark state theoretically. We summarize the main results of our study at last.