Amplification of entangled photon states by klystron

Entangled photon pairs-discrete light quanta that exhibit non-classical correlations-play a central role in quantum information and quantum communication technologies. It is a natural demand from technological applications on the intensity of the entangled photon pairs, such that sufficient signal strength can be achieved. Here we propose approaches based on klystron tubes that could potentially achieve stable amplification of the entangled photon pairs generated by spontaneous parametric down conversion (SPDC) and entanglement transfer.