Środowiskowe Seminarium z Informacji i Technologii Kwantowych

Entanglement is considered as resource in quantum information processing tasks. However, computation of the quantity is often challenging, particularly when the system is of large size, or when it is described by a mixed state -- for example, in the presence of noise. In this talk, we discuss how entanglement, as measured by localizable entanglement, in a noisy topological code of large size, such as the Kitaev's surface code and the color code, can be estimated via an experimentally accessible methodology using entanglement witness operators. We also demonstrate how graph states can be employed in the recipe, and discuss how insight about the distance dependence of entanglement can be obtained. The results are particularly relevant in characterizing the stabilizer states in the case of quantum error correction, where the topological codes serve as ideal candidate systems.