2015/02/28 by Pavel Lougovski, P. Lougovski, D. B. Uskov
Computer Science · Physics and Astronomy · #Channel (broadcasting) #Coincidence #Coincidence counting #Computer science #Optics #Photon #Photon counting #Photon entanglement #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum entanglement #Quantum mechanics #Quantum optics and atomic interactions #Telecommunications #quant-ph
paper · pdf · doi:10.1103/physreva.92.022303
published as Phys. Rev. A 92, 022303 (2015) · resubmitted version, improved presentation, added discussion
arxiv created 2015/06/09 · openalex publication_date 2015/08/04 · openalex created_date 2016/06/24 · arxiv updated 2016/10/13 · openalex updated_date 2026/08/06
Entanglement can effectively increase communication channel capacity as evidenced by dense coding that predicts a capacity gain of 1\phantom\rule4.pt0exbit when compared to entanglement-free protocols. However, dense coding relies on Bell states and when implemented using photons the capacity gain is bounded by 0.585\phantom\rule4.pt0exbits due to one's inability to discriminate between the four optically encoded Bell states. In this paper we study the following question: Are there alternative entanglement-assisted protocols that rely only on linear optics, coincidence photon counting, and separable single-photon input states and at the same time provide a greater capacity gain than 0.585\phantom\rule4.pt0exbits? We show that besides the Bell states there is a class of bipartite four-mode two-photon entangled states that facilitate an increase in channel capacity. We also discuss how the proposed scheme can be generalized to the case of two-photon N-mode entangled states for N=6,8.