Experimental Realization of a Controlled-NOT Gate with Four-Photon Six-Qubit Cluster States

TL;DR

This paper reports the experimental realization of an optical CNOT gate using a 6-qubit cluster state entangled in polarization and spatial modes, demonstrating its potential for quantum computing.

Contribution

First experimental demonstration of a CNOT gate with a 6-qubit cluster state entangled in multiple degrees of freedom.

Findings

Achieved quantum process fidelity estimate.

Proved the gate's entangling capability.

Showed the gate cannot be simulated by local operations and classical communication.

Abstract

We experimentally demonstrate an optical controlled-NOT (CNOT) gate with arbitrary single inputs based on a 4-photon 6-qubit cluster state entangled both in polarization and spatial modes. We first generate the 6-qubit state, and then by performing single-qubit measurements the CNOT gate is applied to arbitrary single input qubits. To characterize the performance of the gate, we estimate its quantum process fidelity and prove its entangling capability. The results show that the gate cannot be reproduced by local operations and classical communication. Our experiment shows that cluster states are promising candidates for efficient optical quantum computation.