2020/11/30 by Mario A. Ciampini, Álvaro Cuevas, Paolo Mataloni +2
Computer Science · Physics and Astronomy · #Amplitude damping channel #Pauli exclusion principle #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum channel #Quantum discord #Quantum entanglement #Quantum mechanics #Qubit #Sigma #Statistical physics #quant-ph
paper · pdf · doi:10.1103/physreva.103.062414
published as Phys. Rev. A 103, 062414 (2021) · 9 pages, 3 figures, 3 tables. Improved version, with tables of experimental conditional probabilities
arxiv created 2021/06/07 · openalex publication_date 2021/06/15 · arxiv updated 2021/06/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We show an experimental procedure to certify the classical capacity for noisy qubit channels. The method makes use of a fixed bipartite entangled state, where the system qubit is sent to the channel input and the set of local measurements, \ensuremathσx\ensuremath\bigotimes\ensuremathσx, \ensuremathσy\ensuremath\bigotimes\ensuremathσy, and \ensuremathσz\ensuremath\bigotimes\ensuremathσz, is performed at the channel output and the ancilla qubit, thus without resorting to full quantum process tomography. The witness to the classical capacity is then achieved by reconstructing sets of conditional probabilities, noise deconvolution, and classical optimization of the pertaining mutual information. The performance of the method to provide lower bounds to the classical capacity is tested by a two-photon polarization entangled state in Pauli channels and amplitude damping channels. The measured lower bounds to the channels are in high agreement with the simulated data, which take into account both the experimental entanglement fidelity F=0.979\ifmmode±\else\textpm\fi0.011 of the input state and the systematic experimental imperfections.