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Unconditional continuous-variable dense coding

Timothy C. Ralph, Elanor H. Huntington

We investigate the conditions under which unconditional dense coding can be achieved using continuous-variable entanglement. We consider the effect of entanglement impurity and detector efficiency and discuss experimental verification. We conclude that the requirements for a strong demonstration are not as stringent as previously thought, and are within the reach of present technology.

arXiv:quant-ph/0208117Physical Review AOct 24, 200251 citations

Continuous-Variable Quantum Computing and its Applications to Cryptography

Do Ngoc Diep, Koji Nagata, Renata Wong

International Journal of Theoretical PhysicsAug 22, 20207 citations

Cloning and cryptography with quantum continuous variables

Nicolas J. Cerf, S. Iblisdir, Gilles Van Assche

arXiv:quant-ph/0107077The European Physical Journal DFeb 1, 200226 citations

Experimental Demonstration of Tripartite Entanglement and Controlled Dense Coding for Continuous Variables

Jietai Jing, Jing Zhang, Ying Lin Yan +3 more

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 3.28 and 3.18 dB, respectively. If the mean photon number n equals 11 the channel capacity can be controllably inverted between 2.91 and 3.14. When n 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.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 3.28 and 3.18 dB, respectively. If the mean photon number n equals 11 the channel capacity can be controllably inverted between 2.91 and 3.14. When n 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.

arXiv:quant-ph/0210132Physical Review LettersApr 23, 2003362 citations

Experimental demonstration of entanglement-assisted coding using a two-mode squeezed vacuum state

Jun Mizuno, Kentaro Wakui, Akira Furusawa +1 more

We have experimentally realized the scheme initially proposed as quantum dense coding with continuous variables [Ban, J. Opt. B: Quantum Semiclassical Opt. 1, L9 (1999); Braunstein and Kimble, Phys. Rev. A 61, 042302 (2000)]. In our experiment, a pair of EPR (Einstein-Podolsky-Rosen) beams is generated from two independent squeezed vacua. After adding a two-quadrature signal to one of the EPR beams, two squeezed beams that contain the signal were recovered. Although our squeezing level is not sufficient to demonstrate the channel capacity gain over the Holevo limit of a single-mode channel without entanglement, our channel is superior to conventional channels such as coherent and squeezing channels. In addition, the optical addition and subtraction processes demonstrated are elementary operations of universal quantum information processing on continuous variables.We have experimentally realized the scheme initially proposed as quantum dense coding with continuous variables [Ban, J. Opt. B: Quantum Semiclassical Opt. 1, L9 (1999); Braunstein and Kimble, Phys. Rev. A 61, 042302 (2000)]. In our experiment, a pair of EPR (Einstein-Podolsky-Rosen) beams is generated from two independent squeezed vacua. After adding a two-quadrature signal to one of the EPR beams, two squeezed beams that contain the signal were recovered. Although our squeezing level is not sufficient to demonstrate the channel capacity gain over the Holevo limit of a single-mode channel without entanglement, our channel is superior to conventional channels such as coherent and squeezing channels. In addition, the optical addition and subtraction processes demonstrated are elementary operations of universal quantum information processing on continuous variables.

arXiv:quant-ph/0402040Physical Review AJan 4, 200579 citations

Continuous-variable quantum computing and its applications to cryptography

Koji Nagata, Do Ngoc Diep, Ahmed Farouk +1 more

Institute of Physics eBooksJul 1, 20220 citations

Experimental Demonstration of Quantum Dense Coding and Quantum Cryptography with Continuous Variables

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