Delayed transfer of entanglement to initially populated qubits

Abstract

The transfer of entangled, quantum correlated, flying photons from a squeezed field to single-mode cavities is investigated. It is shown that, while the transfer of photons begins immediately after the input squeezed field is turned on, the time at which quantum correlations start to be transferred to the cavities is strongly dependent on the initial population of the cavities. For the initially empty cavities, the transfer of quantum correlations begins immediately after the squeezed field is turned on, but it is delayed by a certain time interval when the cavities are initially populated. We find that the transfer of the quantum correlations is postponed until the one-photon states of the system are almost completely depopulated. In other words, the system "waits" for the population of the single-photon states to decay out before starting to build up the quantum correlation between the cavities. The delay time interval is independent of the number of photons initially present in the system, but it is dependent on the decay rates of the cavities and can be varied (controlled) when the cavities decay with different rates. It is shown that the delayed transfer of the quantum correlation is directly related to the presence of quantum jumps, which transfer the population from the entangled to incoherent mixture states.