Research Of Controlled Quantum Teleportation And Secure Direct Communication

Quantum information science is an interdiscipline of computer science,physics,mathematics and informatics.It brings a new direction of information processing and communications and gives the information theory experts and computer scientists a new field worth exploring.Quantum teleportation,which is one aspect of quantum information,plays a significant role in quantum communication and quantum information,and has been extensively studied.Quantum teleportation has been demonstrated by several experimental groups.Recently,people pay more attention to controlled quantum teleportation,where a three-particle entangled state instead of EPR pairs is used to transfer an unknown state.Controlled quantum teleportation is useful in many fields of quantum information processing,such as,quantum cryptography,quantum secure direct communication and so on.In this dissertation,based on the controlled quantum teleportation scheme of Gao et al,we put forward a new controlled quantum secure direct communication protocol—based on arbitrary orthonormal basis(except X-basis).We prove that as long as one uses arbitrary orthogonal basis which is different from X-basis to encode secret information,one can achieve controlled quantum secure direct communication by using Gao et al’s controlled quantum teleportation scheme.Besides the security of the scheme is analyzed.In quantum communication,the quantum channel as a transmission channel is very important.Therefore,we present a method of preparing quantum channels,and conduct a safety test on the quantum channels.Passing the test guarantees the safety of the quantum channel for safe and controlled quantum secure direct communication.