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 χ0 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 S. When noises that cause ESD act, we show that χ0 may lose its capacity for S before ESD occurs. Similarly, χ0 may fail to yield information transfer better than classically possible when the encoding operations are noisy, though entanglement is not destroyed in the process. © 2010 The American Physical Society.