arXiv subjects

Kunchi Peng

Publications and source records attributed to Kunchi Peng.

60 records · Page 4Linked to original sources

arXiv2005

Quantum Key Ditribution Based on Quantum Intensity Correlation of Twin Beams

A new and simple quantum key distribution scheme based on the quantum intensity correlation of optical twin beams and the directly local measurements of intensity noise of single optical beam is presented and experimentally demonstrated. Using the twin beams with the quantum intensity correlation of 5dB the effective bit rate of $2\times 10^7bits/s$ is completed. The noncloning of quantum systems and the sensitivity of the existing correlations to losses provide the physical mechamism for the security against eavesdropping. In the presented scheme the signal modulation and homodyne detection are not needed.

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arXiv2004

Experimental Demonstration of Unconditional Entanglement Swapping for Continuous Variables

The unconditional entanglement swapping for continuous variables is experimentally demonstrated. Two initial entangled states are produced from two nondegenerate optical parametric amplifiers operating at deamplification. Through implementing the direct measurement of Bell-state between two optical beams from each amplifier the remaining two optical beams, which have never directly interacted with each other, are entangled. The quantum correlation degrees of 1.23dB and 1.12dB below the shot noise limit for the amplitude and phase quadratures resulting from the entanglement swapping are straightly measured.

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arXiv2002

Experimental demonstration of tripartite entanglement and controlled dense coding for continuous variables

A tripartite entangled state of bright optical field is experimentally produced using an Einstein-Podolsky-Rosen entangled state for continuous variables and linear optics. The controlled dense coding among a sender, a receiver and a controller is demonstrated by exploiting the tripartite entanglement. The obtained three-mode position correlation and relative momentum correlation between the sender and the receiver and thus the improvements of the measured signal to noise ratios of amplitude and phase signals with respect to the shot noise limit are 3.28dB and 3.18dB respectively. If the mean photon number $\bar{n}$ equals 11 the channel capacity can be controllably inverted between 2.91 and 3.14. When $\bar{n}$ is larger than 1.0 and 10.52 the channel capacities of the controlled dense coding exceed the ideal single channel capacities of coherent and squeezed state light communication.

quant-ph↗

arXiv2002

Quantum Cryptography Using Einstein-Podolsky-Rosen Correlations of Continuous Variables

Quantum cryptography with the predetermined key was experimentally realized using Einstein-Podolsky-Rosen(EPR) correlations of continuously bright optical beams. Only one of two EPR correlated beams is transmitted with the signals modulated on quadrature phases and amplitudes, and the other one is retained by the authorized receiver. The modulated small signals are totally submerged in the large quantum noise of the signal beam, therefore nobody except the authorized receiver can decode the signals. Usability of imperfect quantum correlation, high transmission and detection efficiencies, and security provided by quantum mechanics are the favorable features of the presented scheme.

quant-ph↗

arXiv2001

Quantum Dense Coding Exploiting Bright EPR Beam

Highly efficient quantum dense coding for continuous variables has been experimentally accomplished by means of exploiting bright EPR beam with anticorrelation of amplitude quadratures and correlation of phase quadratures, which is generated from a nondegenerate optical parametric amplifier operating in the state of deamplification. Two bits of classical information are encoded on two quadratures of a half of bright EPR beam at the sender Alice and transmitted to the receiver Bob via one qubit of the shared quantum state after encoding. The amplitude and phase signals are simultaneously decoded with the other half of EPR beam by the direct measurement of the Bell-state at Bob. The signal to noise ratios of the simultaneously measured amplitude and phase signals are improved 5.4dB and 4.8dB with respect to that of the shot noise limit respectively. A high degree of immunity to unauthorized eavesdropping of the presented quantum communication scheme is experimentally demonstrated.

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arXiv2001

Quantum Switch for Continuous Variable Teleportation

A novel quantum switch for continuous variables teleportation is proposed. Two pairs of EPR beams with identical frequency and constant phase relation are composed on two beamsplitters to produce two pairs of conditional entangled beams, two of which are sent to two sending stations(Alices) and others to two receiving stations(bobs). The EPR entanglement initionally results from two-mode quadrature squeezed state light. Converting the squeezed component of one of EPR sources between amplitude and phase, the input quantum state at a sender will be reproduced at two receivers in turn. The switching system manipulated by squeezed state light might be developed as a practical quantum switch device for the communication and teleportation of quantum information.

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