We have investigated [1] 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 have shown that entanglement can be recovered by local pulses only. Entanglement recovery by purely local operations has been illustrated in all-optical experiments [2], by open- or closed-loop control schemes.

Entanglement revival by purely local operations

Open-loop setup

Closed-loop setup

[1] A. D'Arrigo, R. Lo Franco, G. Benenti, E. Paladino and G. Falci, Recovering entanglement by local operations, Ann. Phys. 350, 211 (2014).
[2] A. Orieux, A. D'Arrigo, G. Ferranti, R. Lo Franco, G. Benenti, E. Paladino, G. Falci, F. Sciarrino and P. Mataloni, Sci. Rep. 5, 8575 (2015).