Stability of quantum states of finite macroscopic systems against classical noises, perturbations from environments, and local measurements.
Stability of quantum states of finite macroscopic systems against classical noises, perturbations from environments, and local measurements.
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DOI：
10.1142/9789812704412_0004
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发表时间：
2002-02
影响因子：
8.6
通讯作者：
A. Shimizu;T. Miyadera
中科院分区：
文献类型：
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作者：
A. Shimizu;T. Miyadera
本文研究了有限体积宏观系统的量子态的稳定性，利用定域性和大自由度证明了：（i）如果对一个纯态，每个加性算符的平方涨落都小于或等于O（V），那么它对任何弱经典噪声或环境扰动都不是脆弱的. (ii)如果某个加性算符的平方涨落对纯态为O（V2），则对某些加性算符是脆弱的。(iii)如果一个状态，无论是纯态还是混合态，都具有“簇属性”，那么它对局部测量是稳定的，反之亦然。在众多的应用中，我们讨论了有限系统的破缺机制。
We study the stability of quantum states of macroscopic systems of finite volume V. By using both the locality and huge degrees of freedom, we show the following: (i) If square fluctuation of every additive operator is O(V) or less for a pure state, then it is not fragile for any weak classical noises or weak perturbations from environments. (ii) If square fluctuation of some additive operator is O(V2) for a pure state, then it is fragile for some of these. (iii) If a state, pure or mixed, has the "cluster property," then it is stable against local measurements, and vice versa. Among many applications, we discuss the mechanism of symmetry-breaking in finite systems.