A SINGLE QUANTUM CANNOT BE CLONED
A SINGLE QUANTUM CANNOT BE CLONED
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DOI：
10.1038/299802a0
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发表时间：
1982-01-01
期刊：
影响因子：
64.8
通讯作者：
ZUREK, WH
中科院分区：
文献类型：
--
作者：
WOOTTERS, WK;ZUREK, WH
如果一个具有确定极化的光子遇到一个受激发的原子，该原子通过受激发射发射第二个光子的概率通常是不会消失的。这样的光子保证具有与原始光子相同的偏振。但是，有没有可能通过这个或任何其他过程来放大一个量子态，即产生一个量子系统的几个副本(在目前的情况下是偏振光子)，每个副本都与原始状态相同？如果是这样的话，放大过程可以用来确定量子系统的确切状态：在光子的情况下，人们可以通过首先产生一束相同偏振的副本，然后测量斯托克斯参数1来确定其偏振。我们在这里表明，量子力学的线性禁止这种复制，并且这一结论对所有量子系统都成立。
If a photon of definite polarization encounters an excited atom, there is typically some nonvanishing probability that the atom will emit a second photon by stimulated emission. Such a photon is guaranteed to have the same polarization as the original photon. But is it possible by this or any other process to amplify a quantum state, that is, to produce several copies of a quantum system (the polarized photon in the present case) each having the same state as the original? If it were, the amplifying process could be used to ascertain the exact state of a quantum system: in the case of a photon, one could determine its polarization by first producing a beam of identically polarized copies and then measuring the Stokes parameters1. We show here that the linearity of quantum mechanics forbids such replication and that this conclusion holds for all quantum systems.