Experimental Realization of Entanglement Concentration and A Quantum Repeater

We report an experimental realization of entanglement concentration using two polarization-entangled photon pairs produced by pulsed parametric down-conversion. In the meantime, our setup also provides a proof-in-principle demonstration of a quantum repeater. The quality of our procedure is verified by observing a violation of Bell's inequality by more than 5 standard deviations. The high experimental accuracy achieved in the experiment implies that the requirement of tolerable error rate in multi-stage realization of quantum repeaters can be fulfilled, hence providing a practical toolbox for quantum communication over large distances.Comment: 15 pages, 4 figures, submitte

Experimental demonstration of a non-destructive controlled-NOT quantum gate for two independent photon-qubits

Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum information processing. However, the photons, one of the best candidates for qubits, suffer from the lack of strong nonlinear coupling required for quantum logic operations. Here we show how this drawback can be overcome by reporting a proof-of-principle experimental demonstration of a non-destructive controlled-NOT (CNOT) gate for two independent photons using only linear optical elements in conjunction with single-photon sources and conditional dynamics. Moreover, we have exploited the CNOT gate to discriminate all the four Bell-states in a teleportation experiment.Comment: 4 pages, 4 figures, submitte

Experimental realization of optimal asymmetric cloning and telecloning via partial teleportation

We report an experimental realization of both optimal asymmetric cloning and telecloning of single photons by making use of partial teleportation of an unknown state. In the experiment, we demonstrate that, conditioned on the success of partial teleportation of single photons, not only the optimal asymmetric cloning can be accomplished, but also one of two outputs can be transfered to a distant location, realizing the telecloning. The experimental results represent a novel way to achieve the quantum cloning and may have potential applications in the context of quantum communication.Comment: 4 pages and 4 figure

Experimental Construction of Optical Multi-qubit Cluster States From Bell States

Cluster states serve as the central physical resource for the measurement-based quantum computation. We here present a simple experimental demonstration of the scalable cluster-state-construction scheme proposed by Browne and Rudolph. In our experiment, three-photon cluster states are created from two Bell states using linear optical devices. By observing a violation of three-particle Mermin inequality of $|| = 3.10\pm0.03$, we also for the first time report a genuine three-photon entanglement. In addition, the entanglement properties of the cluster states are examined under $\sigma_z$ and $\sigma_x$ measurements on a qubit.Comment: 4 pages, 4 figures, submitte

Fixed Point Theorem of Ciric-Pata Type

In this article, we proved a fixed point theorem of Ćirić-Pata type in metric space. This result extends several results in the existing literature. Moreover, an example is given in the support of our result. In particular, the main result provides a complete solution to an open problem raised by Kadelburg and Radenović (J. Egypt. Math. Soc. 24 (2016) 77-82)