EurekAlert August 12, 2024
Although progress has been reported in the generation of mutually entangled multi-photon quantum light states using free space apparatus, high-fidelity high-rate on-chip entanglement generation is important for future scalability. An international team of researchers (France, Italy, Brazil) used a bright quantum-dot based single-photon source to demonstrate the high-fidelity generation of 4-photon Greenberg-Horne-Zeilinger (GHZ) states with a low-loss reconfigurable glass photonic circuit. They reconstructed the density matrix of the generated states using full quantum-state tomography reaching an experimental fidelity and purity. The entanglement of the generated states was certified with a semi device-independent approach through the violation of a Bell-like inequality by more than 39 standard deviations. They showed a four-partite quantum secret sharing protocol on-chip where a regulator shared with three interlocutors a sifted key with up to 1978 bits, achieving a qubit-error rate of 10.87%. According to the researchers their results showed that the quantum-dot technology combined with glass photonic circuitry offered a viable path for entanglement generation and distribution… read more. Open Access TECHNICAL ARTICLE
Integrated path-encoded 4-GHZ generator. Credit: npj Quantum Information volume 10, Article number: 50 (2024)