Qubit entanglement between ring-resonator photon-pair sources on a silicon chip

Area of Science:

• Quantum Information Science
• Integrated Photonics
• Quantum Optics

Background:

• Entanglement is a fundamental quantum phenomenon and a key resource for quantum information technologies.
• Scalable quantum devices require on-chip generation and control of entangled qubits, often encoded in photon paths.
• Photonic systems offer a promising platform for quantum information processing due to photons' low decoherence and high speed.

Purpose of the Study:

• To demonstrate a silicon photonic chip capable of generating and analyzing path-entangled two-qubit states.
• To integrate high-performance photonic components for scalable quantum information applications.
• To confirm the high level of on-chip entanglement using quantum state tomography and Bell-CHSH tests.

Main Methods:

• Utilized resonant-enhanced photon-pair sources based on spontaneous four-wave mixing in ring resonators.
• Employed on-chip spectral demultiplexers and reconfigurable optics for state manipulation and analysis.
• Performed quantum state tomography and the Bell-CHSH inequality test to verify entanglement quality.

Main Results:

• Achieved highly indistinguishable photon-pair sources with small spectral correlations.
• Successfully generated a path-entangled two-qubit state on the silicon photonic chip.
• Confirmed high-fidelity on-chip entanglement through rigorous quantum state tomography and Bell-CHSH test violations.

Conclusions:

• Demonstrated the feasibility of generating and analyzing photonic entanglement on a scalable silicon photonic platform.
• Highlighted the integration of high-performance components essential for future quantum devices.
• This work paves the way for harnessing photonic entanglement in large-scale quantum information systems.