2008/03/23 by Julio T. Barreiro, Tzu-Chieh Wei, Paul G. Kwiat · 12 citations
Computer Science · Physics and Astronomy · #Amplitude damping channel #Channel (broadcasting) #Channel capacity #Computer science #Photon #Photonics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum channel #Quantum entanglement #Quantum information science #Quantum mechanics #Quantum network #Superdense coding #Telecommunications #quant-ph
paper · pdf · doi:10.1038/nphys919
published as Nature Phys. 4, 282 (2008) · Letter: 6 pages, 4 figures. Supplementary Information: 4 pages, 1 figure
openalex publication_date 2008/03/23 · arxiv created 2010/09/26 · arxiv updated 2010/09/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Dense coding is arguably the protocol that launched the field of quantum communication. Today, however, more than a decade after its initial experimental realization, the channel capacity remains fundamentally limited as conceived for photons using linear elements. Bob can only send to Alice three of four potential messages owing to the impossibility of carrying out the deterministic discrimination of all four Bell states with linear optics, reducing the attainable channel capacity from 2 to log2 3 ≈ 1.585 bits. However, entanglement in an extra degree of freedom enables the complete and deterministic discrimination of all Bell states. Using pairs of photons simultaneously entangled in spin and orbital angular momentum, we demonstrate the quantum advantage of the ancillary entanglement. In particular, we describe a dense-coding experiment with the largest reported channel capacity and, to our knowledge, the first to break the conventional linear-optics threshold. Our encoding is suited for quantum communication without alignment and satellite communication.