Entangling quantum-logic gate operated with an ultrabright semiconductor single-photon source.

Area of Science:

• Quantum Information Science
• Solid-State Physics
• Photonics

Background:

• Quantum logic gates are fundamental building blocks for quantum computation.
• Solid-state single-photon sources offer scalability and integration potential for photonic quantum technologies.
• Achieving high-fidelity entangling operations is crucial for advancing quantum information processing.

Purpose of the Study:

• To demonstrate an unambiguous entangling operation of a photonic quantum-logic gate.
• To utilize an ultrabright solid-state single-photon source for quantum control and target qubits.
• To characterize the performance of the quantum-logic gate at various source brightness levels.

Main Methods:

• Employed indistinguishable single photons from a single semiconductor quantum dot in a micropillar optical cavity.
• Utilized these photons as control and target qubits for the quantum-logic gate.
• Measured the truth table overlap and Bell-state fidelity at different photon source brightness values.

Main Results:

• Achieved a truth table overlap of 68.4±0.5% with the ideal case at a source brightness of 0.56 photons per pulse, improving to 73.0±1.6% at 0.17 photons per pulse.
• Demonstrated the entangling nature of the gate, with Bell-state fidelity exceeding the 50% threshold.
• Reached a Bell-state fidelity of 71.0±3.6% at a source brightness of 0.15 photons per pulse.

Conclusions:

• The study successfully demonstrated an unambiguous entangling photonic quantum-logic gate.
• The use of a solid-state single-photon source proves effective for high-fidelity quantum operations.
• These findings represent a significant step towards scalable and efficient photonic quantum computing.