Ma Y, Pan X, Cai W, Mu X, Xu Y, Hu L, Wang W, Wang H, Song Y P, Yang Zhen-Biao, Zheng Shi-Biao, Sun L
Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China.
Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China.
Phys Rev Lett. 2020 Oct 30;125(18):180503. doi: 10.1103/PhysRevLett.125.180503.
Quantum correlations in observables of multiple systems not only are of fundamental interest, but also play a key role in quantum information processing. As a signature of these correlations, the violation of Bell inequalities has not been demonstrated with multipartite hybrid entanglement involving both continuous and discrete variables. Here we create a five-partite entangled state with three superconducting transmon qubits and two photonic qubits, each encoded in the mesoscopic field of a microwave cavity. We reveal the quantum correlations among these distinct elements by joint Wigner tomography of the two cavity fields conditional on the detection of the qubits and by test of a five-partite Bell inequality. The measured Bell signal is 8.381±0.038, surpassing the bound of 8 for a four-partite entanglement imposed by quantum correlations by 10 standard deviations, demonstrating the genuine five-partite entanglement in a hybrid quantum system.
多个系统可观测量中的量子关联不仅具有基本的研究意义，而且在量子信息处理中起着关键作用。作为这些关联的一个标志，涉及连续和离散变量的多体混合纠缠尚未证明违反贝尔不等式。在这里，我们利用三个超导传输子量子比特和两个光子量子比特创建了一个五体纠缠态，每个量子比特都编码在一个微波腔的介观场中。我们通过对两个腔场进行基于量子比特检测的联合维格纳断层扫描以及对一个五体贝尔不等式的测试，揭示了这些不同元素之间的量子关联。测量得到的贝尔信号为8.381±0.038，比由量子关联施加的四体纠缠的界限8超出了10个标准差，证明了混合量子系统中真正的五体纠缠。
