Abstract
Quantum entanglement shared by more than two partites is the essential bases for developing quantum communication networks and quantum computation. The multipartite entanglement of continuous variables can be generated by distributing or combining squeezed states of light using linear optics. We experimentally obtained a tripartite entangled state of bright optical field by means of a nondegenerate optical parametric amplifier (NOPA) and optical beam-splitters. The NOPA is operated in the state of parametric deamplification by locking the relative phase between the pump laser and the injected seed wave to (2n+1)π, so the generated Einstein-Podolsky-Rosen (EPR) beam for continuous variables is an entangled state of light with the quantum correlation of phase quadratures and the quantum anticorrelation of amplitude quadratures [1]. The output EPR beam consists of two frequency-degenerate optical modes with horizontal and vertical polarizations which are distributed to three parties with two linear beam-splitters. We have theoretically and experimentally demonstrated the three parties are in a tripartite entangled state with three-mode “position” (amplitude quadrature) correlation and relative “momentum” (phase quadrature) correlation [2]-[4]. The obtained GHZ-like state is a fully inseparable tripartite continuous-variables state violating the three inequalities used for the criterion of the inseparability [5][6]. The controlled dense coding quantum communication is experimentally accomplished by exploiting the tripartite entanglement. The three entangled modes are sent to a sender (Alice), a receiver (Bob) and a controller (Claire), respectively. The information transmission capacity of the quantum channel between Alice and Bob is controlled by Claire. The channel capacity completed under Claire’s help is always larger than that without her help.
© 2004 Optical Society of America
PDF ArticleMore Like This
Hidehiro Yonezawa, Takao Aoki, and Akira Furusawa
ITuJ2 International Quantum Electronics Conference (IQEC) 2004
Jinxia Feng, ’, Hao Zhao, Dandan Nie, Yuanji Li, ’, and Kuanshou Zhang
JTu2A.31 CLEO: Applications and Technology (CLEO:A&T) 2019
F. A. S. Barbosa, A. S. Coelho, K. N. Cassemiro, A. S. Villar, M. Martinelli, and P. Nussenzveig
T4A.2 Quantum Information and Measurement (QIM) 2013