Communication with Unreliable Entanglement Assistance

Entanglement resources can increase transmission rates substantially. Unfortunately, entanglement is a fragile resource that quickly degraded by decoherence effects. In order to generate for optical communication, the transmitter and receiver first prepare entangled spin-photon pairs locally, then photon at sent through an fiber or free space. Without feedback, does not know whether has reached receiver. The present work introduces new model of unreliable assistance, whereby communication system operates assistance not. While sender ignorant, knows generation was successful. case failure, decodes less information. this manner, effective rate adapted according status. Regularized formulas are derived classical quantum capacity regions with characterizing tradeoff between unassisted excess be obtained from assistance. It further established time division entanglement-assisted coding strategies optimal noiseless qubit channel, but strictly suboptimal noisy channel.