The Investigation Of Quantum Entanglement Sharing

Quantum information is a discipline involving quantum mechanics, cryptographyand informatics. With quantum state as the information carrier, it studies the storage andtransmission of information, in order to achieve more in computing speed andsecuritythe than classical information. Quantum entanglement is a peculiar phenomenonin quantum world, with no corresponding in classical world. Entanglement is vitalquantum information resources, which has very important applications in quantumcomputation and quantum communication. The preparation, transmission,distinguishment and nonlocality researches of quantum entangled state are hot topicsin quantum information processing. Especially in quantum communication schemebased on entangled states, the sharing of high-fidelity entangled state between distantparties is the first step to realize quantum communication.Due to its transmission speed, weak in the coupling with the environment and easyto control, photons are considered to be the ideal candidate of quantum communicationentity. A large number of existent quantum communication experiments use thepolarization degree of freedom of photons as information carrier. In most of thequantum communication scheme, communication parties need to share a pair of puremaximum entangled state in advance. But the polarization degree of freedom of photonsis easily affected by the actual environmental noise. In the process of transmission theentangled photons will inevitably interact with the environment which lead todecoherence, not only reduces the purity of entanglement, but also further affect theefficiency and security of quantum communication schemes. Therefore, in the noisyenvironment the fidelity of quantum entanglement sharing has always been a hot issuein the field of quantum communication.This paper researched the development process of quantum entanglement sharing,and introduced the representative schemes of quantum entanglement sharing andquantum entanglement distribution. On this basis, we proposed a quantum entanglementdistribution scheme for W state assisted by frequency degree of freedom. So far, most ofthe existent entanglement purification schemes and entanglement distribution schemesconsider the two-particle Bell entangled state and the GHZ states, not for entangled Wstate sharing. Our design has solved the sharing of W state in quantum communication,which has good application value in the sharing of W state. We should only prepare entanglement on one degree of freedom on initial state, and get the W state inpolarization degree of freedom at the end. In the process of the transmission, we keepentanglement information intact based on that the characteristics of the frequencydegrees of freedom is less affected by the noise. Our scheme has100%successprobability as well. Our scheme is not only suited for W state, but also can be used forarbitrary entangled states. Compared to traditional entanglement purification schemes,We consume less entanglement resource and has high success probability, which makesour protocol have a wider application prospect.