Optimal Local Filtering Operation for Enhancing Quantum Entanglement

Zhaofeng Su, Nina Sukhodoeva

Zhaofeng Su, Nina Sukhodoeva

Hai‐Bo Xing, Ming Yang, Ping Dong +2 more

Chunyu Huang, Wenchao Ma, Liu Ye

Zhaofeng Su, Nina Sukhodoeva

Quantum entanglement is an indispensable resource for many significant quantum information processing tasks. Thus, distilling more entanglement from less entangled resource is a task of practical significance and has been investigated for decades. The literature [Verstraete \textit{et al}., \href{https://link.aps.org/doi/10.1103/PhysRevA.64.010101}{Phys. Rev. A 64, 010101(2001)}] considered a scenario to increase the entanglement by local filtering operation and qualitatively derived the variance relation of entanglement. We investigate the scenario with general two-qubit resources to find the optimal strategy of filtering operations. We obtain the upper bound for the ratio of entanglement increase and find the corresponding optimal local filtering operation to achieve the maximal ratio. Our analysis shows that the upper bound ratio grows with the length of local Bloch vector while the success probability decrease with it. We further extend the research to investigate the optimal measurement strategy by considering general measurement. Our result shows that local measurement can not increase the expectation of quantum entanglement, which gives more analytical evidence to the well known fact that local operation can not create quantum entanglement.

Yen-An Shih, Wan-Guan Chang, Gelo Noel M. Tabia +5 more

The subchannel discrimination task involves distinguishing between different branches of a quantum evolution. The guessing probability of this task can be enhanced using quantum resources such as entanglement and steerability. In this study, we explore how to optimize the task's guessing probability within the one-sided device-independent quantum information processing framework, which is naturally associated with steering, and restricted to one-way local operations and classical communication. From a theoretical standpoint, we demonstrate how to separately optimize local filters and measurements, and provide an optimality condition that directly links the enhancement of guessing probability to the maximum steerability achievable through local filters. We then experimentally demonstrate the enhancement of the discrimination task on a two-ququart photonic system by implementing the optimal local filters.