Unconventional quantum gate based on Rydberg blockade mechanism

We propose a scheme for realizing an unconventional three-qubit controlled-phase gate via the Rydberg blockade mechanism. The qubit is encoded by atomic ensembles that are trapped in optical traps and fixed on an atom chip. Because of the collective nature of the encoding and the Rydberg blockade mechanism, the scheme do not require separate addressing of individual atoms. The time needed for the gate operation is much shorter than that in a similar scheme. In addition, we show the gate can be used as a basic tool for effective generation of large-scale 2D cluster states.