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Author

He Lu

Bio: He Lu is an academic researcher from Shandong University. The author has contributed to research in topics: Quantum entanglement & Quantum network. The author has an hindex of 15, co-authored 47 publications receiving 1749 citations. Previous affiliations of He Lu include University of Science and Technology of China.

Papers
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Journal ArticleDOI
TL;DR: This work created a state-of-the-art platform for multiphoton experiments, and enabled technologies for challenging optical quantum information tasks, such as the realization of Shor's error correction code and high-efficiency scattershot boson sampling.
Abstract: An entangled polarization state of ten photons sets a new record for multiphoton entanglement.

524 citations

Journal ArticleDOI
09 Aug 2012-Nature
TL;DR: The high-frequency and high-accuracy acquiring, pointing and tracking technique developed in this experiment can be directly used for future satellite-based quantum communication and large-scale tests of quantum foundations.
Abstract: Quantum teleportation of independent qubits and entanglement distribution have been demonstrated over free-space channels of about 100 kilometres, representing an important step towards a global quantum network. Free-space channels, in which light propagates freely through the open air, offer advantages over optical fibres for quantum communication because they suffer fewer photon losses and less decoherence. Here, Juan Yin et al. report quantum teleportation of independent qubits over a 97-kilometre one-link free-space channel with multiphoton entanglement. Using a two-link channel, they also demonstrate entanglement distribution over 101.8 kilometres. The results represent an important step towards a global quantum network. In particular, the high-frequency and high-accuracy acquiring, pointing and tracking techniques developed in the experiment could be used directly for future satellite-based quantum communication and large-scale tests of quantum foundations. Transferring an unknown quantum state over arbitrary distances is essential for large-scale quantum communication and distributed quantum networks. It can be achieved with the help of long-distance quantum teleportation1,2 and entanglement distribution. The latter is also important for fundamental tests of the laws of quantum mechanics3,4. Although quantum teleportation5,6 and entanglement distribution7,8,9 over moderate distances have been realized using optical fibre links, the huge photon loss and decoherence in fibres necessitate the use of quantum repeaters10 for larger distances. However, the practical realization of quantum repeaters remains experimentally challenging11. Free-space channels, first used for quantum key distribution12,13, offer a more promising approach because photon loss and decoherence are almost negligible in the atmosphere. Furthermore, by using satellites, ultra-long-distance quantum communication and tests of quantum foundations could be achieved on a global scale. Previous experiments have achieved free-space distribution of entangled photon pairs over distances of 600 metres (ref. 14) and 13 kilometres (ref. 15), and transfer of triggered single photons over a 144-kilometre one-link free-space channel16. Most recently, following a modified scheme17, free-space quantum teleportation over 16 kilometres was demonstrated18 with a single pair of entangled photons. Here we report quantum teleportation of independent qubits over a 97-kilometre one-link free-space channel with multi-photon entanglement. An average fidelity of 80.4 ± 0.9 per cent is achieved for six distinct states. Furthermore, we demonstrate entanglement distribution over a two-link channel, in which the entangled photons are separated by 101.8 kilometres. Violation of the Clauser–Horne–Shimony–Holt inequality4 is observed without the locality loophole. Besides being of fundamental interest, our results represent an important step towards a global quantum network. Moreover, the high-frequency and high-accuracy acquiring, pointing and tracking technique developed in our experiment can be directly used for future satellite-based quantum communication and large-scale tests of quantum foundations.

469 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the creation of an eight-photon Schrodinger-cat state with genuine multipartite entanglement by developing noise-reduction multiphoton interferometer and post-selection detection.
Abstract: Researchers demonstrate the creation of an eight-photon Schrodinger-cat state with genuine multipartite entanglement by developing noise-reduction multiphoton interferometer and post-selection detection. The ability to control eight individual photons will enable new multiphoton entanglement experiments in previously inaccessible parameter regimes.

408 citations

Journal ArticleDOI
TL;DR: By employing a six-photon entangled state, this work demonstrates a quantum threshold scheme, where the shared quantum secrecy can be efficiently reconstructed with a state fidelity as high as 93% and demonstrates that the scheme meets the confidentiality criterion.
Abstract: Secret sharing of a quantum state, or quantum secret sharing, in which a dealer wants to share a certain amount of quantum information with a few players, has wide applications in quantum information. The critical criterion in a threshold secret sharing scheme is confidentiality: with less than the designated number of players, no information can be recovered. Furthermore, in a quantum scenario, one additional critical criterion exists: the capability of sharing entangled and unknown quantum information. Here, by employing a six-photon entangled state, we demonstrate a quantum threshold scheme, where the shared quantum secrecy can be efficiently reconstructed with a state fidelity as high as 93%. By observing that any one or two parties cannot recover the secrecy, we show that our scheme meets the confidentiality criterion. Meanwhile, we also demonstrate that entangled quantum information can be shared and recovered via our setting, which shows that our implemented scheme is fully quantum. Moreover, our experimental setup can be treated as a decoding circuit of the five-qubit quantum error-correcting code with two erasure errors.

64 citations

Journal ArticleDOI
TL;DR: In this paper, a nested purification protocol is developed by combining entanglement purification and swapping, which works for the spontaneous parametric downconversion sources as well as other physical systems that suffer from double-pair emission noise.
Abstract: Quantum repeaters 1–4 are essential elements for demonstrating global-scale quantum communication. Over the past few decades, tremendous efforts have been dedicated to implementing a practical quantum repeater 5–10 . However, nested purification 1 , the backbone of a quantum repeater, remains a challenge because the capacity for successive entanglement manipulation is still absent. Here, we propose and demonstrate an architecture of nested purification using spontaneous parametric downconversion sources 11 . A heralded entangled photon pair with higher fidelity is successfully purified from two copies of low-fidelity pairs that experience entanglement swapping and noisy channels. By delicately designing the optical circuits, double-pair emission noise is eliminated automatically and the purified state can be used for scalable entanglement connections to extend the communication distance. Combined with a quantum memory, our approach can be applied immediately in the implemention of a practical quantum repeater. A nested purification protocol is developed by combining entanglement purification and swapping. It works for the spontaneous parametric downconversion sources as well as other physical systems that suffer from double-pair emission noise.

60 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
09 Aug 2017-Nature
TL;DR: This work reports the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD—a form ofQKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected.
Abstract: Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

1,216 citations

Journal ArticleDOI
TL;DR: A review of the progress in photonic quantum information processing can be found in this article, where the emphasis is given to the creation of photonic entanglement of various forms, tests of the completeness of quantum mechanics (in particular, violations of local realism), quantum information protocols for quantum communication, and quantum computation with linear optics.
Abstract: Multiphoton interference reveals strictly nonclassical phenomena. Its applications range from fundamental tests of quantum mechanics to photonic quantum information processing, where a significant fraction of key experiments achieved so far comes from multiphoton state manipulation. The progress, both theoretical and experimental, of this rapidly advancing research is reviewed. The emphasis is given to the creation of photonic entanglement of various forms, tests of the completeness of quantum mechanics (in particular, violations of local realism), quantum information protocols for quantum communication (e.g., quantum teleportation, entanglement purification, and quantum repeater), and quantum computation with linear optics. The scope of the review is limited to ``few-photon'' phenomena involving measurements of discrete observables.

1,156 citations