arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 1911.00599quant-ph
收藏

改进的子空间见证纠缠检测

Improved entanglement detection with subspace witnesses

Won Kyu Calvin Sun, Alexandre Cooper, Paola Cappellaro

发表信息：
Phys. Rev. A 101, 012319 (2020)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

纠缠虽然在许多量子应用中至关重要，但很难在实验上表征。虽然基于对目标纠缠态的保真度的纠缠见证是有效的纠缠检测器，但由于状态准备和测量过程中的误差，它们通常会低估纠缠量。因此，为了在存在这种控制误差的情况下更鲁棒地检测纠缠，我们引入了一个“子空间”证人，该证人检测到更广泛的一类纠缠态，具有比传统的状态保真度证人更大的违反，同时保持更有效的状态层析成像。我们实验证明了子空间见证的优势，通过产生和检测纠缠的混合，两个量子比特系统组成的电子自旋在钻石。我们进一步扩展子空间证人的概念，以具体的真正的多体纠缠（GME）状态，如GHZ，W，和Dicke状态，并激励选择的度量基于量子信息任务，如纠缠增强传感。此外，由于子空间见证标识的目标纠缠态的多体相干，它有助于（超越检测）通过广义并发纠缠的下界量化。我们希望子空间证人的直接和有效的实现将有利于在具有100个量子比特的噪声中等规模量子处理器中检测特定的GME状态。

英文摘要：

Entanglement, while being critical in many quantum applications, is difficult to characterize experimentally. While entanglement witnesses based on the fidelity to the target entangled state are efficient detectors of entanglement, they in general underestimate the amount of entanglement due to errors during state preparation and measurement. Therefore, to detect entanglement more robustly in the presence of such control errors, we introduce a 'subspace' witness that detects a broader class of entangled states with strictly larger violation than the conventional state-fidelity witness at the cost of additional measurements, while remaining more efficient with respect to state tomography. We experimentally demonstrate the advantages of the subspace witness by generating and detecting entanglement with a hybrid, two-qubit system composed of electronic spins in diamond. We further extend the notion of subspace witness to specific genuine multipartite entangled (GME) states such as GHZ, W, and Dicke states, and motivate the choice of the metric based on quantum information tasks such as entanglement-enhanced sensing. In addition, as the subspace witness identifies the many-body coherences of the target entangled state, it facilitates (beyond detection) lower-bound quantification of entanglement via generalized concurrences. We expect the straightforward and efficient implementation of subspace witnesses would be beneficial in detecting specific GME states in noisy, intermediate-scale quantum processors with a hundred qubits.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑