Experimental Demonstration of Controlled-$$Z$$ Gate for Continuous Variables

Abstract

AbstractWe experimentally demonstrate a unity-gain controlled-\(Z\) gate for optical continuous-variable one-way quantum computation. The resource state is a four-mode linear cluster state, which is generated by combining four squeezed states on three beam splitters. A two-mode input state, which is prepared independently of the cluster, is coupled with the cluster state via teleportation-based input-coupling schemes. Our experiment can be considered as an experimental demonstration of two-mode gate teleportation as well. The quantum nature of the gate is verified through the presence of entanglement at the output. By combining with the demonstrations of one-mode Gaussian operations we have recently reported in Ref. [1], we now have all the tools required to implement an arbitrary multi-mode Gaussian operation in a framework of one-way quantum computation.KeywordsControlled-\(z\) gateTwo-mode Gaussian operationGate teleportationEntanglement detection