标题： 辅助可近似量子态变换 显示英文标题

标题： Ancilla Approximable Quantum State Transformations

摘要： 我们考虑通过以下过程可获得的量子态变换。 将给定的输入态与辅助系统的特殊准备的初始态结合。 对组合系统应用一个幺正变换。 测量辅助子系统的态。 如果（且仅当）它处于指定的最终态，则认为该过程成功，并将原始（主要）系统的相应态作为该过程的结果。 我们回顾关于通过此类过程精确实现变换的已知信息。 然后我们提出关于有限部分变换近似实现的结果。 我们主要考虑在指定的正epsilon范围内的逼近问题，但我们也讨论任意接近逼近的问题。 显示英文摘要

摘要： We consider the transformations of quantum states obtainable by a process of the following sort. Combine the given input state with a specially prepared initial state of an auxiliary system. Apply a unitary transformation to the combined system. Measure the state of the auxiliary subsystem. If (and only if) it is in a specified final state, consider the process successful, and take the resulting state of the original (principal) system as the result of the process. We review known information about exact realization of transformations by such a process. Then we present results about approximate realization of finite partial transformations. We consider primarily the issue of approximation to within a specified positive epsilon, but we also address the question of arbitrarily close approximation.