标题： 非对易混合态不能被广播 显示英文标题

标题： Noncommuting mixed states cannot be broadcast

摘要： We show that, given a general mixed state for a quantum system, there are no physical means for {\it 广播} that state onto two separate quantum systems, even when the state need only be reproduced marginally on the separate systems. This result generalizes and extends the standard no-cloning theorem for pure states. 显示英文摘要

摘要： We show that, given a general mixed state for a quantum system, there are no physical means for {\it broadcasting\/} that state onto two separate quantum systems, even when the state need only be reproduced marginally on the separate systems. This result generalizes and extends the standard no-cloning theorem for pure states.