Superadditive communication with the green machine as a practical demonstration of nonlocality without entanglement.

ABSTRACT: Achieving the ultimate Holevo limit of optical communication capacity requires a joint-detection receiver that makes a collective quantum measurement over multiple modulated symbols. Such superadditivity-a higher communication rate than is achievable by symbol-by-symbol optical detection-is a special case of the well-known nonlocality without entanglement and has yet to be demonstrated. In this article, we propose and demonstrate the design of a joint-detection receiver, the Green Machine, that can achieve superadditivity. We build this receiver, experimentally obtain the transition probability matrix induced by the codebook-receiver pair, and deduce that its capacity surpasses that of any symbol-by-symbol receiver in the photon-starved regime for binary-phase-shift-keying (BPSK)modulation

SUBMITTER: Cui C 

PROVIDER: S-EPMC12015425 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature