  We investigate the phenomenon of bipartite entanglement revivals under purely
local operations in systems subject to local and independent classical noise
sources. We explain this apparent paradox in the physical ensemble description
of the system state by introducing the concept of "hidden" entanglement, which
indicates the amount of entanglement that cannot be exploited due to the lack
of classical information on the system. For this reason this part of
entanglement can be recovered without the action of non-local operations or
back-transfer process. For two noninteracting qubits under a low-frequency
stochastic noise, we show that entanglement can be recovered by local pulses
only. We also discuss how hidden entanglement may provide new insights about
entanglement revivals in non-Markovian dynamics.
