Realtime generation of the bell states by linear-nonlocal measurements and bang-bang control

Abstract

We present a realtime feedback control scheme to deterministically produce the maximally entangled Bell states of two partially separated atoms. The recently introduced concept of SWM- (simultaneous weak measurements)-induced quantum state reduction is generalized to the case of anti-commutative observables. This generalization enables the probabilistic preparation of the Bell states via the SWMs of one linear observable and one nonlocal observable. The deterministic generation of the desired Bell state is then carried out by combining SWM-induced quantum state reduction with feedback control. The realtime implementation of the proposed control scheme is guaranteed by using the time delay control approach in which the computation time of filter-based control is compensated for by the delay time in control input.