Construction Of Polarized Bit Quantum Logic Gate Assisted By Multi-Degree Of Freedom

Compared with classical computers,quantum computers have faster computing speed and less energy consumption,so the development of quantum computers has attracted extensive attention.The quantum logic gate is an indispensable part of the construction of quantum computer and the realization of secure quantum communication,so the design of appropriate quantum logic gate can make the quantum computer have faster computing speed and simpler circuit.In recent years,some progress has been made in the construction of quantum logic gates using optical systems.By using auxiliary single photon,linear optical elements,photon nondestructive detector and classical feedforward system,the construction of double-qubit and three-qubit universal logic gates can be realized.Compared with linear optical logic gates,the probability of success is greatly improved.However,the development of quantum logic gate has made remarkable progress both in theory and in experiment.In this paper,a three-photon Toffoli gate is proposed by using linear optical elements and quantum nondestructive detection with the aid of multi-degree-of-freedom,and it is extended to a polarized multi-photon controlled single-photon monopoton gate.The first chapter of this paper introduces the research background of quantum logic gates.The second chapter of this paper introduces some basic knowledge of quantum qubit,quantum entanglement,linear optical element and quantum logic gate.In the third chapter of this paper,the construction scheme of multi-degree-of-freedom assisted polarizable qubit Toffoli logic gate is proposed,and the fidelity of three-photon Toffoli logic gate is calculated according to the definition of fidelity.In the fourth chapter of this paper,we propose a multi-DOF polarized multi-photon control scheme for single photon unitary gate.The construction process of this scheme is divided into control path process,unitary transformation process and output process.Using cross Kerr nonlinear effec,X zero difference measurement,time delay device,the logic gate construction circuit is simplified,the feasibility of the scheme is analyzed.