Deterministic Controlled-NOT gate for single-photon two-qubit quantum logic

摘要

We demonstrate a robust implementation of a deterministic linear-opticalControlled-NOT (CNOT) gate for single-photon two-qubit quantum logic. Apolarization Sagnac interferometer with an embedded 45$^{\circ}$-oriented doveprism is used to enable the polarization control qubit to act on the momentum(spatial) target qubit of the same photon. The CNOT gate requires no activestabilization because the two spatial modes share a common path, and it is usedto entangle the polarization and momentum qubits.