Abstract
We consider the optimal cloning of quantum coherent states with single-clone and joint fidelity as figures of merit. While the latter is maximized by a Gaussian cloner, the former is not: the optimal single-clone fidelity for a symmetric 1-to-2 cloner is 0.6826, compared to in a Gaussian setting. This cloner can be realized with an optical parametric amplifier and certain non-Gaussian bimodal states. Finally, we show that the single-clone fidelity of the optimal cloner is . It is achieved by a Gaussian scheme and cannot be surpassed even with supplemental bound entangled states.
- Received 7 October 2004
DOI:https://doi.org/10.1103/PhysRevLett.95.070501
©2005 American Physical Society