Quantum steering of Gaussian states via non-Gaussian measurements.
Quantum steering of Gaussian states via non-Gaussian measurements.
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DOI：
10.1038/srep29729
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发表时间：
2016-07-14
影响因子：
4.6
通讯作者：
Nha H
中科院分区：
文献类型：
--
作者：
Ji SW;Lee J;Park J;Nha H
量子操控-即使在一方或其测量设备完全不可信的情况下也要验证的强相关性-不仅提供了对量子物理的深刻见解，也为实际应用提供了至关重要的基础。对于连续变量(CV)系统，高斯态等已被广泛研究，但大多局限于高斯量测。虽然满足高斯标准就足以检测到CV转向，但在许多情况下，它是否也是高斯态所必需的是一个基本的重要问题。这严重质疑了仅在高斯测量下建立的特征描述的有效性，如转向的量化和一夫一妻制关系。在这里，我们介绍了一种基于非高斯测量的局域不确定关系的形式，它表明了一些高斯标准无法检测到的高斯态的量子操控。为此，我们研究了具有实际意义的高斯态，即有损耗和放大的高斯信道下的双模压缩态。我们的发现极大地修正了目前已建立的高斯态操控特性，如一夫一妻关系和高斯量测下的单向操控，从而为超越高斯态的批判性研究开辟了新的方向。
Quantum steering—a strong correlation to be verified even when one party or its measuring device is fully untrusted—not only provides a profound insight into quantum physics but also offers a crucial basis for practical applications. For continuous-variable (CV) systems, Gaussian states among others have been extensively studied, however, mostly confined to Gaussian measurements. While the fulfilment of Gaussian criterion is sufficient to detect CV steering, whether it is also necessary for Gaussian states is a question of fundamental importance in many contexts. This critically questions the validity of characterizations established only under Gaussian measurements like the quantification of steering and the monogamy relations. Here, we introduce a formalism based on local uncertainty relations of non-Gaussian measurements, which is shown to manifest quantum steering of some Gaussian states that Gaussian criterion fails to detect. To this aim, we look into Gaussian states of practical relevance, i.e. two-mode squeezed states under a lossy and an amplifying Gaussian channel. Our finding significantly modifies the characteristics of Gaussian-state steering so far established such as monogamy relations and one-way steering under Gaussian measurements, thus opening a new direction for critical studies beyond Gaussian regime.