The primary aims of the present proposed project is to study entanglement decoherence of many-body qubits or multilevel quantum systems and to develop a quantum trajectory approach in several important AMO physics domains. Two examples are: entanglement dynamics of multilevel atomic systems coupled to a quantized field and non-Markovian trajectories for quantum systems coupled to a fermionic environment. Our primary interest of application is quantum decoherence of quantum open systems in AMO and condensed matter systems and the simulation of quantum entanglement dynamics of many-body systems.
Quantum coherence dynamics of open systems is a generic paradigm that has been widely discussed in research fields ranging from atomic and optical physics to condensed matter physics and to quantum information science. Among current research frontiers are decoherence, dissipation, disentanglement and non-Markovian dynamical theory. Realistic quantum systems designed for quantum information processing (QIP) cannot avoid interactions with their environments, which can alter their quantum coherence and entanglement properties. Environment-induced quantum decoherence undermines the effectiveness or even feasibility of QIP and is thus of primary concern in the actual design of quantum computers and quantum information processing tasks. Investigation of dynamical aspect of quantum open systems is both of practical and theoretical significance. Particularly, mastering how quantum coherence and entanglement in a quantum system interacting with an environment evolves in time is of vital importance for QIP and quantum technology in general. The environmental noises can be caused by many different sources. For example, electrons in a metal or impurity in a solid can cause the loss of quantum coherence that is crucial for quantum information processing. Roughly speaking, there are two types of environmental noises: bosonic and fermionic noises. The former is typically represented by photons or phonons, while electrons or spins can cause the latter. For bosonic noises, we have quite a few techniques to deal with the quantum dynamics such as master equations, path integral, quantum trajectories etc. In particular, the stochastic method developed for bosonic noises is shown to be very efficient in numerical simulations for quantum open systems. It is highly desirable to develop a new approach that can be efficiently used to study quantum decoherence, dissipation and disentanglement of open systems coupled to fermionic reservoirs. In the project, we had made several important progresses in understanding entanglement dynamics and non-Markovian quantum open systems. These include: We have systematically established the theory of fermionic Schroedinger equations for quantum open systems coupled to a fermionic noise. By using the fermionic Schroedinger equations, we have established a set of exact master equations for a large class of quantum open systems interacting with a fermionic bath and spin bath. We extended recent theoretical studies of entanglement dynamics ?in the presence of environmental noise. We investigated the quantum entanglement dynamics of many-body system in the presence of both classical and quantum noises. Moreover, we studied entanglement dynamics in the presence of correlated environmental?noises. In addition, we have developed a new non-perturbative quantum dynamical control approach to a set of quantum open systems via quantum state diffusion. Our research presents a significant advance in the theory of quantum open system, quantum optics and quantum information science. In particular, our research has provided a brand new approach to solving quantum coherence dynamics of open systems coupled to both bosonic and fermionic ?environments. The project has also provided an important platform to train young quantum theorists specializing in quantum optics, quantum information and quantum technology.
