We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation(Hong-Yi Fan and Jun-Hua Chen,J.Phys.A35(2002)6873)to two-mode case.In this appro...We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation(Hong-Yi Fan and Jun-Hua Chen,J.Phys.A35(2002)6873)to two-mode case.In this approach the two-photon master equations can be directly and conveniently converted into c-number partial differential equations.As an example,we solve the typical master equation for two-photon process in some limiting cases.展开更多
Telecom-band polarization-entangled photon- pair source has been widely used in quantum communi- cation due to its acceptable transmission loss. It is also used in cooperation with wavelength-division multiplexing （...Telecom-band polarization-entangled photon- pair source has been widely used in quantum communi- cation due to its acceptable transmission loss. It is also used in cooperation with wavelength-division multiplexing （WDM） to construct entanglement distributor. However, previous schemes generally are not suitable for multinode scenario. In this paper, we construct a telecom-band po- larization-entangled photon-pair source, and it shows ul- trahigh fidelity and concurrence which are both greater than 90 % （raw data）. Moreover, we set up a four-by-four entanglement distributor based on WDM. We check the 16 Clauser-Horne-Shimony-Holt inequalities, which show nonlocality. Lastly, as an example of practical application of this source, we estimate the quantum bit error rates and quantum secret key rates when it is used in quantum key distribution. Furthermore, the transmission of entanglement in long optical fibers is also demonstrated.展开更多
We present an efficient faithful multipartite polarization entanglement distribution protocol over an ar- bitrary noisy channel. The spatial degree of freedom is used to carry the entanglement during the transmission....We present an efficient faithful multipartite polarization entanglement distribution protocol over an ar- bitrary noisy channel. The spatial degree of freedom is used to carry the entanglement during the transmission. We describe the principle by distributing n-qubit Greenberge-Horne--Zeilinger state and n-qubit W state. Our scheme can be used to distribute arbitrary n-qUbit entangled states to n distant locations. The remote parties can obtain maximally entangled states deterministically on the polarization of photons. Only passive linear optics are employed in our setup, which makes our scheme more feasible and efficient for practical application in long distance quantum communication.展开更多
We propose a novel quantum key distribution scheme by using the SAM-OAM hybrid entangled state as the physical resource.To obtain this state,the polarization entangled photon pairs are created by the spontaneous param...We propose a novel quantum key distribution scheme by using the SAM-OAM hybrid entangled state as the physical resource.To obtain this state,the polarization entangled photon pairs are created by the spontaneous parametric down conversion process,and then,the q-plate acts as a SAM-to-OAM transverter to transform the polarization entangled pairs into the hybrid entangled pattern,which opens the possibility to exploit the features of the higher-dimensional space of OAM state to encode information.In the manipulation and encoding process,Alice performs the SAM measurement by modulating the polarization stateπ lθx on one photon,whereas Bob modulates the OAM sector state lx' on the other photon to encode his key elements using the designed holograms which is implemented by the computer-controlled SLM.With coincidence measurement,Alice could extract the key information.It is showed that N-based keys can be encoded with each pair of entangled photon,and this scheme is robust against Eve’s individual attack.Also,the MUBs are not used.Alice and Bob do not need the classical communication for the key recovery.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No.10175057the President Foundation of the Chinese Academy of Sciences
文摘We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation(Hong-Yi Fan and Jun-Hua Chen,J.Phys.A35(2002)6873)to two-mode case.In this approach the two-photon master equations can be directly and conveniently converted into c-number partial differential equations.As an example,we solve the typical master equation for two-photon process in some limiting cases.
基金This work was supported by the National Nat- ural Science Foundation of China （61327901, 61490711, 11274289, 11325419, 11374288 and 11104261）, the National Basic Research Program of China （2011CB921200）, the Strategic Priority Research Program （B） of the Chinese Academy of Sciences （XDB01030300）, the National Science Ftmd for Distinguished Young Scholars （61225025）, and the Fundamental Research Funds for Central Universities （WK2470000011）.
文摘Telecom-band polarization-entangled photon- pair source has been widely used in quantum communi- cation due to its acceptable transmission loss. It is also used in cooperation with wavelength-division multiplexing （WDM） to construct entanglement distributor. However, previous schemes generally are not suitable for multinode scenario. In this paper, we construct a telecom-band po- larization-entangled photon-pair source, and it shows ul- trahigh fidelity and concurrence which are both greater than 90 % （raw data）. Moreover, we set up a four-by-four entanglement distributor based on WDM. We check the 16 Clauser-Horne-Shimony-Holt inequalities, which show nonlocality. Lastly, as an example of practical application of this source, we estimate the quantum bit error rates and quantum secret key rates when it is used in quantum key distribution. Furthermore, the transmission of entanglement in long optical fibers is also demonstrated.
基金Supported by the National Natural Science Foundation of China under Grant No.11004258Fundamental Research Funds for the Central Universities under Grant No.CQDXWL-2012-014
文摘We present an efficient faithful multipartite polarization entanglement distribution protocol over an ar- bitrary noisy channel. The spatial degree of freedom is used to carry the entanglement during the transmission. We describe the principle by distributing n-qubit Greenberge-Horne--Zeilinger state and n-qubit W state. Our scheme can be used to distribute arbitrary n-qUbit entangled states to n distant locations. The remote parties can obtain maximally entangled states deterministically on the polarization of photons. Only passive linear optics are employed in our setup, which makes our scheme more feasible and efficient for practical application in long distance quantum communication.
基金supported by the National Cryptography Development Foundation of China(Grant No.MMJJ201401011)the Science and Technology Program of Guangzhou,China(Grant Nos.2013J4500095 and 2014J4100050)
文摘We propose a novel quantum key distribution scheme by using the SAM-OAM hybrid entangled state as the physical resource.To obtain this state,the polarization entangled photon pairs are created by the spontaneous parametric down conversion process,and then,the q-plate acts as a SAM-to-OAM transverter to transform the polarization entangled pairs into the hybrid entangled pattern,which opens the possibility to exploit the features of the higher-dimensional space of OAM state to encode information.In the manipulation and encoding process,Alice performs the SAM measurement by modulating the polarization stateπ lθx on one photon,whereas Bob modulates the OAM sector state lx' on the other photon to encode his key elements using the designed holograms which is implemented by the computer-controlled SLM.With coincidence measurement,Alice could extract the key information.It is showed that N-based keys can be encoded with each pair of entangled photon,and this scheme is robust against Eve’s individual attack.Also,the MUBs are not used.Alice and Bob do not need the classical communication for the key recovery.
