Leggett-Garg inequality violations with a large ensemble of qubits
Leggett-Garg inequality violations with a large ensemble of qubits
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DOI：
10.1103/physreva.94.012105
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发表时间：
2016-04
影响因子：
2.9
通讯作者：
Neill Lambert;Kamanasish Debnath;A. F. Kockum;G. Knee;W. Munro;F. Nori
中科院分区：
文献类型：
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作者：
Neill Lambert;Kamanasish Debnath;A. F. Kockum;G. Knee;W. Munro;F. Nori
我们研究如何在准宏观系统中的离散内部自由度影响违反Leggett-Garg不等式，时间相关函数的基础上的宏观现实主义的测试。作为一个具体的例子，我们专注于集体和个人噪声的量子位的合奏。这种通用模型可以描述一系列物理系统，包括腔中的原子，金刚石中氮空位（NV）中心的电子或核自旋，Y2 SiO 5中的铒，硅中的铋杂质，或超导电路阵列，仅举几例。这样的大集合可能比迄今为止用于测试Leggett-Garg不等式的其他系统更宏观，并开辟了一条在宏观尺度上探索量子力学边界的途径。我们发现，由于这种合奏的非平凡的内部结构，不同的测量方案的行为，在噪声的影响下，可以是令人惊讶的。我们讨论了哪些测量方案是最佳的通量量子比特和NV中心，以及一些技术限制和困难，观察这种违反与当今的实验。
We investigate how discrete internal degrees of freedom in a quasimacroscopic system affect the violation of the Leggett-Garg inequality, a test of macroscopic realism based on temporal correlation functions. As a specific example, we focus on an ensemble of qubits subject to collective and individual noise. This generic model can describe a range of physical systems, including atoms in cavities, electron or nuclear spins in nitrogen-vacancy (NV) centers in diamond, erbium in Y2SiO5, bismuth impurities in silicon, or arrays of superconducting circuits, to indicate but a few. Such large ensembles are potentially more macroscopic than other systems that have been used so far for testing the Leggett-Garg inequality and open a route toward probing the boundaries of quantum mechanics at macroscopic scales. We find that, because of the nontrivial internal structure of such an ensemble, the behavior of different measurement schemes, under the influence of noise, can be surprising. We discuss which measurement schemes are optimal for flux qubits and NV centers, and some of the technological constraints and difficulties for observing such violations with present-day experiments.