title: Orbital Angular Momentum-Entanglement Frequency Transducer.
abstract: Entanglement is a vital resource for realizing many tasks such as teleportation, secure key distribution, metrology, and quantum computations. To effectively build entanglement between different quantum systems and share information between them, a frequency transducer to convert between quantum states of different wavelengths while retaining its quantum features is indispensable. Information encoded in the photon's orbital angular momentum (OAM) degrees of freedom is preferred in harnessing the information-carrying capacity of a single photon because of its unlimited dimensions. A quantum transducer, which operates at wavelengths from 1558.3 to 525 nm for OAM qubits, OAM-polarization hybrid-entangled states, and OAM-entangled states, is reported for the first time. Nonclassical properties and entanglements are demonstrated following the conversion process by performing quantum tomography, interference, and Bell inequality measurements. Our results demonstrate the capability to create an entanglement link between different quantum systems operating in a photon's OAM degrees of freedom, which will be of great importance in building a high-capacity OAM quantum network.
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Zhi-Yuan
authors.initials: ZY
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Shi-Long
authors.initials: SL
authors.lastname: Liu
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Ding
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Shi
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Ming-Xin
authors.initials: MX
authors.lastname: Dong
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Bao-Sen
authors.initials: BS
authors.lastname: Shi
authors.affiliation: Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Guang-Can
authors.initials: GC
authors.lastname: Guo