Non-Markovian Dynamics In Open Quantum Systems And Delayed Choice Experiment

Quantum mechanics depict the magic world we live in an atom scale. Its theory contains a lot of intriguing concepts and languages that contradict our daily life, like entanglement, quantum steering, complementarity and so on. Schrodinger’s cat described the evolution of an isolated quantum systm. While, in general most quantum systems are not isolated and they interact with their environments. Those nonisolated systems are called open systems.The interaction between the open system and its environment leads to decoherence and dissipation, which is detrimental to their quantum characters, like entanglement. Coherence and entanglement are fundamental resources for information process in quantum information and computation theory. Due to the interaction between the quantum system and the environment, the information stored in the quantum state will finally be completely destroyed. That is the so called decoherence and it is the hard rock for quantum information process. How to avoid the negative effect caused by decoherence has become one of the most important problems in quantum physics. It affects not only quantum information process, but also many other fields. The key to solve the problem is to protect the coherence of the quantum system from being destroyed by the environment wthin the time needed to control and store the quantum state. It is the goal of the study on non-Markovian dynamics in open quantum systems.The wave-particle duality dates back to Einstein’s explanation of the photoelectric effect through quanta of light and de Broglie’s hypothesis of matter waves. The uncertainty principle is at the center of quantum mechanics. Wheeler’s delayed choice experiment gave an answer to the arguement between Einstein’s reality and Bohr’s complementarity and led to an improvement of quantum theory and the related techniques.This paper illustrated the background and the experimental progress of the non-Markovian dynamics in open quantum systems theory and delayed choice experiment, and introduced briefly our two works related as follows:1. non-Markovian discrete qubit dynamics.Although the interaction between the open system and its environment may cause decoherence, sometimes a quantum control can lead to an information feedback from the environment to the system. We proposed a discrete qubit open system scheme in which one can change the interaction between system and environment via local quantum controls. We implemented this experiment in linear optical system and showed how the transition from Markovian to non-Markovian dynamics can be controlled using only local operations for the open system.2, Delayed choice experiment scheme with a classical superposition of particle state and wave state.Like the quantum delayed choice experiment scheme proposed by lonicioiu, we put forward to a delayed choice scheme in which the particle state and wave state could be in a classical superposition in each interfering experiment. By changing a related parameter we can observe a transition from particle like behavior to wave like behavior. This proposal also raised a problem that as the device resolution become higher, one can choose the time to measure a particle state within its wave package and the time we choose may affect the result.