Hidden entanglement in the presence of random telegraph dephasing noise

Entanglement dynamics of two noninteracting qubits, locally affected by random telegraph noise at pure dephasing, exhibits revivals. These revivals are not due to the action of any nonlocal operation, thus their occurrence may appear paradoxical since entanglement is by definition a nonlocal resource. We show that a simple explanation of this phenomenon may be provided by using the (recently introduced) concept of “hidden” entanglement, which signals the presence of entanglement that may be recovered with the only help of local operations.