Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria.
Phys Rev Lett. 2019 Nov 1;123(18):180503. doi: 10.1103/PhysRevLett.123.180503.
The first generation of multiqubit quantum technologies will consist of noisy, intermediate-scale devices for which active error correction remains out of reach. To exploit such devices, it is thus imperative to use passive error protection that meets a careful trade-off between noise protection and resource overhead. Here, we experimentally demonstrate that single-qubit encoding can significantly enhance the robustness of entanglement and coherence of four-qubit graph states against local noise with a preferred direction. In particular, we explicitly show that local encoding provides a significant practical advantage for phase estimation in noisy environments. This demonstrates the efficacy of local unitary encoding under realistic conditions, with potential applications in multiqubit quantum technologies for metrology, multipartite secrecy, and error correction.
第一代多量子比特量子技术将由嘈杂的中等规模设备组成，这些设备的主动纠错仍然遥不可及。因此，为了利用这种设备，必须使用被动错误保护，在噪声保护和资源开销之间进行仔细的权衡。在这里，我们通过实验证明，单量子比特编码可以显著提高具有优先方向的四量子比特图态的纠缠和相干性对局部噪声的鲁棒性。特别是，我们明确表明，局部编码为噪声环境中的相位估计提供了显著的实际优势。这证明了局部幺正编码在现实条件下的有效性，在多量子比特量子技术的计量学、多方保密和纠错等领域具有潜在的应用。
