2016/12/31 by Álvaro Cuevas, Massimiliano Proietti, Mario A. Ciampini +5 · 2 citations
Computer Science · Mathematics · Physics and Astronomy · #Bipartite graph #Discrete mathematics #Mathematics #Observable #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum channel #Quantum entanglement #Quantum mechanics #Qubit #Sigma #quant-ph
paper · pdf · doi:10.1103/physrevlett.119.100502
published as Phys. Rev. Lett. 119, 100502 (2017) · 5 pages and 3 figures in the principal article, and 4 pages in the supplementary material
openalex publication_date 2017/09/08 · arxiv created 2017/09/26 · arxiv updated 2017/09/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present an efficient experimental procedure that certifies nonvanishing quantum capacities for qubit noisy channels. Our method is based on the use of a fixed bipartite entangled state, where the system qubit is sent to the channel input. A particular set of local measurements is performed at the channel output and the ancilla qubit mode, obtaining lower bounds to the quantum capacities for any unknown channel with no need of quantum process tomography. The entangled qubits have a Bell state configuration and are encoded in photon polarization. The lower bounds are found by estimating the Shannon and von Neumann entropies at the output using an optimized basis, whose statistics is obtained by measuring only the three observables \ensuremathσx\ensuremath\bigotimes\ensuremathσx, \ensuremathσy\ensuremath\bigotimes\ensuremathσy, and \ensuremathσz\ensuremath\bigotimes\ensuremathσz.