2020/03/31 by Shang Yu, Yu Meng, Raj B. Patel +15
Computer Science · Mathematics · Physics and Astronomy · #Channel (broadcasting) #Classical capacity #Coherent information #Coherent states #Computer science #Dephasing #Erasure #Mathematical economics #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum channel #Quantum information #Quantum mechanics #Statistical physics #Superadditivity #Telecommunications #Zero (linguistics) #quant-ph
paper · pdf · doi:10.1103/physrevlett.125.060502
published as Phys. Rev. Lett. 125, 060502 (2020)
arxiv created 2020/04/15 · openalex publication_date 2020/08/06 · arxiv updated 2020/08/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present an experimental approach to construct a dephrasure channel that contains both dephasing and erasure noises and can be used as an efficient tool to study the superadditivity of coherent information. Using a three-fold dephrasure channel, the superadditivity of coherent information is observed, and a substantial gap is found between the zero single-letter coherent information and zero quantum capacity. Particularly, we find that, when the coherent information of n channel uses is zero, with a larger number of channel uses the quantum capacity becomes positive. These phenomena exhibit a more obvious superadditivity of coherent information than previous works and demonstrate a higher threshold for nonzero quantum capacity. Such novel channels built in our experiment also can provide a useful platform to study the nonadditive properties of coherent information and quantum channel capacity.