%0 Journal Article %J Journal of Mathematical Physics %D 2008 %T Existence of Universal Entangler %A Jianxin Chen %A Runyao Duan %A Zhengfeng Ji %A Mingsheng Ying %A Jun Yu %X A gate is called entangler if it transforms some (pure) product states to entangled states. A universal entangler is a gate which transforms all product states to entangled states. In practice, a universal entangler is a very powerful device for generating entanglements, and thus provides important physical resources for accomplishing many tasks in quantum computing and quantum information. This Letter demonstrates that a universal entangler always exists except for a degenerated case. Nevertheless, the problem how to find a universal entangler remains open. %B Journal of Mathematical Physics %V 49 %P 012103 %8 2008/01/01 %G eng %U http://arxiv.org/abs/0704.1473v2 %N 1 %! J. Math. Phys. %R 10.1063/1.2829895