最新工作:

 

 

 

 

 

Demonstration of Monogamy Relations for Einstein-Podolsky-Rosen Steering in Gaussian Cluster States


Xiaowei Deng, Yu Xiang, Caixing Tian, Gerardo Adesso, Qiongyi He, Qihuang Gong, Xiaolong Su, Changde Xie, and Kunchi Peng


   Understanding how quantum resources can be quantified and distributed over many parties has profound applications in quantum communication. As one of the most intriguing features of quantum mechanics, Einstein-Podolsky-Rosen (EPR) steering is a useful resource for secure quantum networks. By reconstructing the covariance matrix of a continuous variable four-mode square Gaussian cluster state subject to asymmetric loss, we quantify the amount of bipartite steering with a variable number of modes per party, and verify recently introduced monogamy relations for Gaussian steerability, which establish quantitative constraints on the security of information shared among different parties. We observe a very rich structure for the steering distribution, and demonstrate one-way EPR steering of the cluster state under Gaussian measurements, as well as one-to-multimode steering. Our experiment paves the way for exploiting EPR steering in Gaussian
cluster states as a valuable resource for multiparty quantum information tasks.

 

 

Phys. Rev. Lett. 118, 230501 (2017)   PDF

 

 

 

 

 

 

 

 

 

 

 

 

Quantum Entanglement Swapping between Two Multipartite Entangled States


Xiaolong Su, Caixing Tian, Xiaowei Deng, Qiang Li, Changde Xie, and Kunchi Peng


   Quantum entanglement swapping is one of the most promising ways to realize the quantum connection among local quantum nodes. In this Letter, we present an experimental demonstration of the entanglement swapping between two independent multipartite entangled states, each of which involves a tripartite Greenberger-Horne-Zeilinger (GHZ) entangled state of an optical field. The entanglement swapping is implemented deterministically by means of a joint measurement on two optical modes coming from the two multipartite entangled states respectively and the classical feedforward of the measurement results. After entanglement swapping the two independent multipartite entangled states are merged into a large entangled state in which all unmeasured quantum modes are entangled. The entanglement swapping between a tripartite GHZ state and an Einstein-Podolsky-Rosen entangled state is also demonstrated and the dependence of the resultant entanglement on transmission loss is investigated. The presented experiment provides a feasible technical reference for constructing more complicated quantum networks.

 

 

Phys. Rev. Lett. 117, 240503 (2016)   PDF

 

 

 

 

 

 

 

 

 

Five-wave-packet quantum error correction based on continuous-variable cluster entanglement

 

Shuhong Hao, Xiaolong Su, Caixing Tian,Changde Xie, and Kunchi Peng


   Quantum error correction protects the quantum state against noise and decoherence   in quantum communication and quantum computation, which enables one to perform fault   -torrent quantum information processing. We experimentally demonstrate a quantum error   correction scheme with a five-wave-packet code against a single stochastic error, the   original theoretical model of which was firstly proposed by S. L. Braunstein and T. A.   Walker. Five submodes of a continuous variable cluster entangled state of light are used for five encoding channels. Especially, in our encoding scheme the information of the input   state is only distributed on three of the five channels and thus any error appearing in the   remained two channels never affects the output state, i.e. the output quantum state is   immune from the error in the two channels. The stochastic error on a single channel is   corrected for both vacuum and squeezed input states and the achieved fidelities of the   output states are beyond the corresponding classical limit.

 

 

Sci. Rep. 5, 15462 (2015)   PDF

 

 

 

 

 

Gate sequence for continuous variable one-way quantum computation

 

Xiaolong Su, Shuhong Hao, Xiaowei Deng, Lingyu Ma, Meihong Wang, XiaojunJia,

Changde Xie, and Kunchi Peng


   Measurement-based one-way quantum computation using cluster states as resources   providesan efficient model to perform computation and information processing of quantum   codes. Arbitrary Gaussian quantum computation can be implemented sufficiently by   longsingle-mode and two-mode gate sequences. However, continuous variable gate   sequences have not been realized so far due to an absence of cluster states larger than four   submodes.Here we present the first continuous variable gate sequence consisting of a   single-modesqueezing gate and a two-mode controlled-phase gate based on a six-mode   cluster state. The quantum property of this gate sequence is confirmed by the fidelities and   the quantum entanglement of two output modes, which depend on both the squeezing and   controlledphase gates.  The experiment demonstrates the feasibility of implementing   Gaussian  quantum computation by means of accessible gate sequences.

 

 

Nature Communications 4, 2828 (2013)   PDF

 

 

 

 

 

Experimental preparation of eight-partite cluster state for photonic qumodes

 

Xiaolong Su, Yaping Zhao, Shuhong Hao, Xiaojun Jia, Changde Xie, and Kunchi Peng*

 

  The preparation of multipartite entangled states is the prerequisite for exploring quantum   information networks and quantum computation. In this Letter, we present what we believe  is the first experimental demonstration of an eightpartite spatially separated continuous   variable (CV) cluster state of optical modes. Via the linearly optical transformation of eight   squeezed states of light, the eight-partite cluster entangled state with amplitude and phase   quadrature correlations are prepared. The generated eight entangled photonic qumodes are   spatially separated, which provides valuable quantum resources for implementing CV   quantum information protocols.

 

 

Opt. Lett., 37, 5178 (2012)  PDF