Experimental Demonstration of Tripartite Entanglement and Controlled Dense Coding for Continuous Variables
Abstract
A tripartite entangled state of bright optical field is experimentally produced using an EinsteinPodolskyRosen 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 threemode “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 3.28 and 3.18dB, respectively. If the mean photon number n̄ equals 11 the channel capacity can be controllably inverted between 2.91 and 3.14. When n̄ is larger than 1.0 and 10.52, the channel capacity of the controlled dense coding is predicted to exceed the ideal single channel capacity of coherent and squeezed state light communication, respectively.
 Publication:

Physical Review Letters
 Pub Date:
 April 2003
 DOI:
 10.1103/PhysRevLett.90.167903
 arXiv:
 arXiv:quantph/0210132
 Bibcode:
 2003PhRvL..90p7903J
 Keywords:

 03.67.Hk;
 03.65.Ud;
 03.67.Mn;
 42.50.Dv;
 Quantum communication;
 Entanglement and quantum nonlocality;
 Entanglement production characterization and manipulation;
 Nonclassical states of the electromagnetic field including entangled photon states;
 quantum state engineering and measurements;
 Quantum Physics
 EPrint:
 8 pages, 4 figures