Experimental Demonstration of Gain-Tunable Entangling Gate for Continuous Variables

Abstract

We experimentally demonstrate a gain-tunable entangling gate for optical continuous-variable one-way quantum computation, where a three-mode linear Gaussian cluster state is utilized as a resource state. Our gate has the ability of on-off switching of two-mode interactions, as well as interaction-gain tuning. The control of operation is perfectly achieved by adjusting the relative phase in a homodyne detection, which represents the feature of one-way quantum computation: the selection of measurement basis determines the quantum operations. Entanglement at the output for each operation is verified by acquiring the PT symplectic eigenvalue and logarithmic negativity $E_N$. The measurement results of $E_N$ range from $E_N=0$ for the non-entangling operation, to $E_N=0.39\pm 0.05$ for the entangling operation with maximum interaction gain. Our gate can be directly incorporated into a large-scale multi-mode one-way quantum computation.