  We demonstrate unambiguous entangling operation of a photonic quantum-logic
gate driven by an ultrabright solid-state single-photon source.
Indistinguishable single photons emitted by a single semiconductor quantum dot
in a micropillar optical cavity are used as target and control qubits. For a
source brightness of 0.56 collected photons-per-pulse, the measured truth table
has an overlap with the ideal case of 68.4%, increasing to 73.0% for a source
brightness of 0.17 photons- per-pulse. The gate is entangling: at a source
brightness of 0.48, the Bell-state fidelity is above the entangling threshold
of 50%, and reaches 71.0% for a source brightness of 0.15.
