Experimental quantum-enhanced estimation of a lossy phase shift
Experimental quantum-enhanced estimation of a lossy phase shift
复制标题
有损相移的量子增强估算实验
DOI：
10.1038/nphoton.2010.39
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发表时间：
2010-06-01
期刊：
影响因子：
35
通讯作者：
Walmsley, I. A.
中科院分区：
文献类型：
--
作者：
Kacprowicz, M.;Demkowicz-Dobrzanski, R.;Walmsley, I. A.
光学干涉测量法（1）是量子增强精确计量的范例，它能够通过测量相移来感测不同的物理量。当使用标准光源时，相位确定的精度受到散粒噪声的限制，散粒噪声的起源可以追溯到单个光子从干涉仪中出现的随机方式。量子纠缠提供了一种超越这个极限的方法（2-6），著名的例子是N 00 N态（7-10），它在精度上达到了海森堡极限（11），但在损失时非常脆弱（12-14）。相比之下，我们提出的实验证据表明，当存在损耗时，适当设计的量子态（15）在相位估计的精度方面优于标准态和N 00 N态。这表明，即使存在退相干，计量学的量子增强也是可能的，并且实现增强的策略与保护光中编码的量子信息完全不同（16，17）。
A paradigm for quantum-enhanced precision metrology is found in optical interferometry(1), which is capable of sensing diverse physical quantities through measurement of a phase shift. When standard light sources are used, the precision of the phase determination is limited by shot noise, the origin of which can be traced to the random manner in which individual photons emerge from the interferometer. Quantum entanglement provides a means to exceed this limit(2-6) with the celebrated example of N00N states(7-10), which saturate the ultimate Heisenberg limit on precision(11), but are extremely fragile to losses(12-14). In contrast, we present experimental evidence that appropriately engineered quantum states(15) outperform both standard and N00N states in the precision of phase estimation when losses are present. This shows that the quantum enhancement of metrology is possible even when decoherence is present, and that the strategy for realizing the enhancement is quite distinct from protecting quantum information encoded in light(16,17).