Imai Satoya, Tóth Géza, Gühne Otfried
Naturwissenschaftlich-Technische Fakultät, <a href="https://ror.org/02azyry73">Universität Siegen</a>, Walter-Flex-Straße 3, 57068 Siegen, Germany.
<a href="https://ror.org/04mmhnh95">QSTAR</a>, <a href="https://ror.org/02dp3a879">INO-CNR</a>, and <a href="https://ror.org/04x48z588">LENS</a>, Largo Enrico Fermi, 2, 50125 Firenze, Italy.
Phys Rev Lett. 2024 Aug 9;133(6):060203. doi: 10.1103/PhysRevLett.133.060203.
The concept of randomized measurements on individual particles has proven to be useful for analyzing quantum systems and is central for methods like shadow tomography of quantum states. We introduce collective randomized measurements as a tool in quantum information processing. Our idea is to perform measurements of collective angular momentum on a quantum system and actively rotate the directions using simultaneous multilateral unitaries. Based on the moments of the resulting probability distribution, we propose systematic approaches to characterize quantum entanglement in a collective-reference-frame-independent manner. First, we show that existing spin-squeezing inequalities can be accessible in this scenario. Next, we present an entanglement criterion based on three-body correlations, going beyond spin-squeezing inequalities with two-body correlations. Finally, we apply our method to characterize entanglement between spatially separated two ensembles.
对单个粒子进行随机测量的概念已被证明对分析量子系统很有用，并且是诸如量子态的影子层析成像等方法的核心。我们引入集体随机测量作为量子信息处理中的一种工具。我们的想法是在量子系统上进行集体角动量测量，并使用同步多边酉算符主动旋转方向。基于所得概率分布的矩，我们提出了以与集体参考系无关的方式表征量子纠缠的系统方法。首先，我们表明在这种情况下可以得到现有的自旋压缩不等式。接下来，我们提出了一种基于三体关联的纠缠判据，超越了基于两体关联的自旋压缩不等式。最后，我们应用我们的方法来表征空间上分离的两个系综之间的纠缠。
