On The Creation Of Quantum Entanglement Via Quantum Measurement-based Feedback Control And The Application Of Quantum Entanglement

With the development of quantum physics and control theory,quantum control as a new cross research direction was born to research the evolution of quantum system and its control problem from the perspective of cybernetics.Actually,quantum feedback control can be considered as an important part of quantum control theory,and a growing number of works have appeared of theoretical analysis and experimental research in this area.Since quantum entanglement physical resources can be used to improve the abilities of some information systems,the creation of quantum entanglement based on quantum measurement-based feedback control and the application of quantum entanglement are important issues for quantum control theory.Hence,we study the creation and application problem of quantum entanglement in this thesis.The main content can be presented as follow:First,the theoretical and experimental progresses of quantum measurement-based feedback control have been studied.We have analyzed two typical methods of quantum weak continuous measurement,photon count and homodyne detection.The Markivon feedback control model and the Bayesian model have been discussed from the measurement style,control protocol and application range.Then a comparison has been made between these two models.Second,we explore how to deterministically generate symmetric multi-qubit entanglement states in the cavity quantum electrodynamics system with the aid of quantum measurement-based feedback control.From an actual physical system,a corresponding quantum control model has been established.The concrete implementation procedures of the feedback strategy are presented in detail.In addition,the feasibility of the control scheme in preparing classical entanglement states is explicitly demonstrated by some numerical simulations.Third,we propose some novel schemes for quantum teleportation based on different conditions of quantum entanglement resource.When only the sender has the information of quantum channel,or the sender and the receiver only have partial information of entanglement state,an arbitrary quantum state can be transmitted with the aid of ancillary particls and appropriate local unitary operations.Additionally,the physical realizations of our proposals are discussed based on the cavity quantum electrodynamics system.Forth,remote state preparation has been studied in terms of the attached situations of quantum entanglement resource.A comparison has been made between quantum teleportation and remote state preparation.When only the sender has the information of quantum channel,or the sender and the receiver only have partial information of entanglement state,the relative proposals for remote state preparation have been presented with the help of local operations,entanglement resources and classical cost.According to the review of theoretical and experimental works of quantum control,we explore how to deterministically generate symmetric multi-qubit entanglement states with the aid of quantum measurement-based feedback control.Moreover,the application problem has been studied in this thesis.I hope that the works of this thesis could be used to expand the field of quantum control theory and the application of quantum entanglement.