Study On Quantum Entanglement In One-dimensional Spin-dependent Chain

With the development of the times,the traditional information science has been unable to meet the needs of people.Quantum technology has the advantages of good security and large information capacity in information,and has been applied to information science,forming a new field——quantum informatics.As a basic property of micro quantum states,quantum entanglement becomes an important resource to realize quantum information processing,so it is of great significance to study quantum entanglement.The main content of this paper is divided into three parts:Firstly,considering the spin exchange between scattering particles and electrons,the spin entanglement in the one-dimensional scattering problem of Kondo particles to single electron states,double electron states and double Kondo particles to single electron states is studied by solving the schrodinger equation by using the split wave method.the study found that when free electrons pass through Kondo particles,the spin direction of both electrons and Kondo particles may change,Kondo particle scattering changes the proportion of spin of different components in the incident electron state;Kondo particle scattering can cause entanglement between two non-interacting electrons,and the degree of entanglement depends on the initial state and scattering.potential height;the degree of electron entanglement can be effectively controlled by properly adjusting the barrier height;the scattering of free electrons by two spin-variable Kondo particles can generate spin entanglement between two distant,non-interacting scattering particles,and the degree of entanglement is closely related to the selection of the initial state of the system.Secondly,based on heisenberg spin chain model,the thermal entanglement negativity between two-bit and four-bit XYZ heisenberg spin chain two-particle spin is studied for both open-chain and closed-loop boundary conditions,respectively.The results show that when the external magnetic field is uniform,the negative value reaches the maximum,the smaller the external magnetic field B?parameter?and the larger the temperature T,the larger the Z direction coupling parameter corresponding to the maximum negative value.For four-bit XYZ sea the thermal entanglement of adjacent bits of the senburg spin chain,the smaller the B?T,the greater the J??and the greater the degree of negative value,while the influence of?almost disappears after the J_z is greater than a certain value;compared with the closed loop,the negative value at the open chain platform is smaller.For the thermal entanglement of four-bit XYZ heisenberg spin chain interphase bits,the range of negative degree variation of the closed loop is similar to that of the adjacent bit closed loop,except that the platform disappears and has more depressions,and the maximum value of negative degree is obviously smaller;unlike the closed loop,the platform part still exists and decreases with the increase of J_z.The negative value of the interval bit is obviously smaller than that of the adjacent bit.Finally,the spin entanglement with time in an isolated spin chain system is studied by using a four-bit XYZ heisenberg spin chain as a quantum channel.The spin entanglement degree is characterized by a symbiotic entanglement degree.The transmission fidelity is used to characterize the information transmission perfection.The transmission of single-bit and double-bit quantum states along the spin chain is studied.The results show that the higher the J,the smaller the J_z,the shorter the period of the entanglement to the initial maximum entangled state,the less the recovery time of the maximum entanglement is affected by the B??and T.The single quantum state can be transmitted from one end of heisenberg spin chain to the other end in a certain period of time to achieve the perfect transmission of the quantum state.the smaller the J_z,the larger the J,the faster the transmission speed;the larger the double bit maximum entangled state can be transmitted from one end of heisenberg spin chain to the other end in a certain period of time,the smaller the J_z,the larger the J,the faster the transmission speed,and the B magnetic induction intensity has no effect on the transmission speed of the double bit entanglement state.