Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628CJ Delft, Netherlands.
Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, A-1090 Vienna, Austria.
Phys Rev Lett. 2018 Nov 30;121(22):220404. doi: 10.1103/PhysRevLett.121.220404.
Over the past few decades, experimental tests of Bell-type inequalities have been at the forefront of understanding quantum mechanics and its implications. These strong bounds on specific measurements on a physical system originate from some of the most fundamental concepts of classical physics-in particular that properties of an object are well-defined independent of measurements (realism) and only affected by local interactions (locality). The violation of these bounds unambiguously shows that the measured system does not behave classically, void of any assumption on the validity of quantum theory. It has also found applications in quantum technologies for certifying the suitability of devices for generating quantum randomness, distributing secret keys and for quantum computing. Here we report on the violation of a Bell inequality involving a massive, macroscopic mechanical system. We create light-matter entanglement between the vibrational motion of two silicon optomechanical oscillators, each comprising approx. 10^{10} atoms, and two optical modes. This state allows us to violate a Bell inequality by more than 4 standard deviations, directly confirming the nonclassical behavior of our optomechanical system under the fair sampling assumption.
在过去的几十年里，贝尔型不等式的实验检验一直处于理解量子力学及其含义的前沿。这些对物理系统特定测量的强约束来自经典物理学的一些最基本概念——特别是物体的性质在测量时是明确的（实在论），并且仅受局部相互作用的影响（局域性）。这些约束的违反毫不含糊地表明，所测量的系统不具有经典行为，而无需对量子理论的有效性做出任何假设。它还在量子技术中找到了应用，用于验证设备生成量子随机性、分发密钥和进行量子计算的适用性。在这里，我们报告了一个涉及大规模宏观机械系统的贝尔不等式的违反。我们在两个硅光机械振荡器的振动运动之间创建了光物质纠缠，每个振荡器由大约 10^{10}个原子和两个光学模式组成。这种状态使我们能够通过超过 4 个标准差来违反贝尔不等式，直接证实了我们的光机械系统在公平抽样假设下的非经典行为。
