Memory effect of a dephasing channel on measurement uncertainty, dense coding, teleportation, and quantum Fisher information

Abstract

We investigate measurement uncertainty of two incompatible observables, dense coding capacity, teleportation fidelity, and quantum Fisher information for two qubits traversing sequentially a dephasing channel modeled by the multimode bosonic field. Using a memory factor determined by the time separation between two channel uses and the transmit time of each qubit, it is shown that the memory effect of this channel on these four quantum characteristics is state-dependent. It is beneficial for some initial states and detrimental for the other states. There is also circumstance in which the memory effects with different origins have different influences on these quantum characteristics. These results may enrich our comprehension on the interplay between memory effect of a channel and decoherence process of a multi-qubit system.