Effects of quantum noises and noisy quantum operations on entanglement and special dense coding

Abstract

We show how noncommuting noises could cause a Bell state ${\ensuremath{\chi}}_{0}$ to suffer entanglement sudden death (ESD). ESD may similarly occur when a noisy operation acts, if the corresponding Hamiltonian and Lindblad operator do not commute. We study the implications of these in special dense coding $\mathcal{S}$. When noises that cause ESD act, we show that ${\ensuremath{\chi}}_{0}$ may lose its capacity for $\mathcal{S}$ before ESD occurs. Similarly, ${\ensuremath{\chi}}_{0}$ may fail to yield information transfer better than classically possible when the encoding operations are noisy, though entanglement is not destroyed in the process.