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arXiv 1409.4440quant-ph
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更紧密的量子不确定性关系来自于一般的概率界

Tighter quantum uncertainty relations follow from a general probabilistic bound

Florian Fröwis, Roman Schmied, Nicolas Gisin

摘要:

像海森堡-罗伯逊或时间-能量不确定关系(UR)通常被认为是量子理论的标志。在这里,一个简单的推导这些UR的基础上提出了一个单一的经典不等式估计理论,一个Cramér-Rao-like界。然后利用玻恩定则和薛定谔方程得到了Heisenberg-Robertson UR。这使得量子力学的概率性质与希尔伯特空间结构和动力学定律有了明确的区分。它还简化了对界限的解释。此外,通过用所谓的量子费舍尔信息代替一个方差,对混合态的海森堡-罗伯逊UR进行了收紧。热态的哈密顿量均匀间隙的能级饱和的自然选择的运营商更紧密的约束。这个例子进一步扩展到谐振子的高斯态。对于多量子比特系统,我们说明了纠缠和饱和UR自旋压缩态和迪克态的运营商的结构之间的相互作用。

英文摘要:

Uncertainty relations (URs) like the Heisenberg-Robertson or the time-energy UR are often considered to be hallmarks of quantum theory. Here, a simple derivation of these URs is presented based on a single classical inequality from estimation theory, a Cramér-Rao-like bound. The Heisenberg-Robertson UR is then obtained by using the Born rule and the Schrödinger equation. This allows a clear separtion of the probabilistic nature of quantum mechanics from the Hilbert space structure and the dynamical law. It also simplifies the interpretation of the bound. In addition, the Heisenberg-Robertson UR is tightened for mixed states by replacing one variance by the so-called quantum Fisher information. Thermal states of Hamiltonians with evenly-gapped energy levels are shown to saturate the tighter bound for natural choices of the operators. This example is further extended to Gaussian states of a harmonic oscillator. For many-qubit systems, we illustrate the interplay between entanglement and the structure of the operators that saturate the UR with spin-squeezed states and Dicke states.

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