Squeezing and Entanglement in Continuous Variable Systems
XIA Yun-Jie1,2, GUO Guang-Can1
1Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026
2Department of Physics, Qufu Normal University, Qufu, 273165
Squeezing and Entanglement in Continuous Variable Systems
XIA Yun-Jie1,2;GUO Guang-Can1
1Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026
2Department of Physics, Qufu Normal University, Qufu, 273165
Abstract： Based on total variance of a pair of Einstein-Podolsky-Rosen (EPR) type operators, the generalized EPR entangled states in continuous variable systems are defined. We show that such entangled states must correspond to two-mode squeezing states whether these states are Gaussian or not and whether they are pure or not. With help of the relation between the total variance and the entanglement, the degree of such entanglement is also defined. Through analysing some specific cases, we see that this method is very convenient and easy in practical applications. In addition, an entangled state with no squeezing is studied, which reveals that there certainly exists something unknown about entanglement in continuous variable systems.
2004, Vol. 21 
