Construction Of Quantum Logic Gatesbased On Weak Cross-Kerr Nonlinearities

In recent years,quantum information processing technology has gradually moved from theory to experiment,and the feasibility has been greatly improved.However,due to the complexity of the linear optical method circuit,the construction is difficult and the success rate is low.It is very difficult to rely only on this method to complete quantum information processing tasks such as quantum parallel computing and quantum key distribution.Therefore,under the joint efforts of a large number of researchers,a method of nonlinear optics was proposed.Photons are used as carriers in the process of quantum information processing.Using quantum entangled states and strong coherence properties,information is encoded and transmitted.Utilizing the non-locality of entangled states,non-classical correlations,and other quantum properties of microscopic systems,in principle,secure quantum safety communication can be achieved absolutely.Based on quantum computing and quantum information processing technology,a new and highly efficient information processing and information security transmission system will be established in the future.Based on the rapid development of quantum information technology in recent years,this paper proposes a scheme of constructing specific quantum states by using weak cross-Kerr nonlinearities and some optical components.This article is divided into four chapters.First of all,we introduce the quantum information technology development process and the present situation briefly.The second chapter briefly introduces the physics used in the article related knowledge,simple optical components:polarization beam splitter,half wave plate and so on.The third chapter introduces the parity analysis process,the implementation of the entanglement gate,and the construction of the controlled not gate based on the weak cross-Kerr nonlinearity by using an auxiliary photon.In the fourth chapter,using the exchange gates to exchange the quantum states of two target photons,and using the two merged gate circuits to simplify the path of the quantum system,a construction scheme of the approximate deterministic Fredkin gate based on the weak cross-Kerr nonlinearity is proposed.