QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands.
Phys Rev Lett. 2019 Aug 2;123(5):050401. doi: 10.1103/PhysRevLett.123.050401.
We report on the realization and application of nondestructive three-qubit parity measurements on nuclear spin qubits in diamond. We use high-fidelity quantum logic to map the parity of the joint state of three nuclear spin qubits onto an electronic spin qubit that acts as an ancilla, followed by a single-shot nondestructive readout of the ancilla combined with an electron spin echo to ensure outcome-independent evolution of the nuclear spins. Through the sequential application of three such parity measurements, we demonstrate the generation of genuine multipartite entangled states out of the maximally mixed state. Furthermore, we implement a single-shot version of the Greenberger-Horne-Zeilinger experiment that can generate a quantum versus classical contradiction in each run. Finally, we test a state-independent noncontextuality inequality in eight dimensions. The techniques and insights developed are relevant for fundamental tests as well as for quantum information protocols such as quantum error correction.
我们报告了在金刚石中实现和应用无损三量子位奇偶测量的情况，该方法基于核自旋量子位。我们使用高保真量子逻辑将三个核自旋量子位的联合态的奇偶性映射到作为辅助量子位的电子自旋量子位上，然后对辅助量子位进行单次无损读出，并结合电子自旋回波来确保核自旋的演化与结果无关。通过顺序应用三个这样的奇偶测量，我们展示了从最大混合态中生成真正的多体纠缠态。此外，我们还实现了单量子位版本的 GHZ 实验，该实验可以在每次运行中产生量子与经典的矛盾。最后，我们在八个维度上测试了一个状态无关的非定域性不等式。所开发的技术和见解不仅对基本测试具有重要意义，而且对量子信息协议（如量子纠错）也具有重要意义。
