Chip-to-chip quantum teleportation and multi-photon entanglement in silicon (1911.07839v2)

Abstract: Exploiting semiconductor fabrication techniques, natural carriers of quantum information such as atoms, electrons, and photons can be embedded in scalable integrated devices. Integrated optics provides a versatile platform for large-scale quantum information processing and transceiving with photons. Scaling up the integrated devices for quantum applications requires highperformance single-photon generation and photonic qubit-qubit entangling operations. However, previous demonstrations report major challenges in producing multiple bright, pure and identical single-photons, and entangling multiple photonic qubits with high fidelity. Another notable challenge is to noiselessly interface multiphoton sources and multiqubit operators in a single device. Here we demonstrate on-chip genuine multipartite entanglement and quantum teleportation in silicon, by coherently controlling an integrated network of microresonator nonlinear single-photon sources and linear-optic multiqubit entangling circuits. The microresonators are engineered to locally enhance the nonlinearity, producing multiple frequencyuncorrelated and indistinguishable single-photons, without requiring any spectral filtering. The multiqubit states are processed in a programmable linear circuit facilitating Bell-projection and fusion operation in a measurement-based manner. We benchmark key functionalities, such as intra-/inter-chip teleportation of quantum states, and generation of four-photon Greenberger-HorneZeilinger entangled states. The production, control, and transceiving of states are all achieved in micrometer-scale silicon chips, fabricated by complementary metal-oxide-semiconductor processes. Our work lays the groundwork for scalable on-chip multiphoton technologies for quantum computing and communication.

• The paper demonstrates scalable quantum teleportation and multi-photon entanglement by leveraging silicon micro-ring resonators to enhance the SFWM process.
• It experimentally achieves four-photon GHZ state generation with a Bell state fidelity of 0.851 and single-qubit teleportation with an average fidelity of 0.906.
• The approach integrates nonlinear photon sources with linear-optic circuits, paving the way for distributed quantum computing and secure communication networks.

Chip-to-Chip Quantum Teleportation and Multi-Photon Entanglement in Silicon

The paper presents a significant advancement in integrated quantum photonics, demonstrating the potential for scalable quantum information systems within silicon platforms. The research focuses on two key areas: chip-to-chip quantum teleportation and the generation and control of multi-photon entangled states, specifically showcasing capabilities within a silicon-based architecture.

Technical Advances and Methodology

The authors have utilized micro-ring resonators (MRRs) fabricated on silicon-on-insulator platforms to enhance the spontaneous four-wave mixing (SFWM) process. This method enhances photon generation, achieving high heralding efficiency and spectral purity without the necessity for narrowband spectral filtering. Notably, the MRRs have a quality factor exceeding $10^4$, enabling a photon generation enhancement by a factor of approximately 43 when on resonance, compared to off-resonance conditions.

By integrating networks of nonlinear photon sources and linear-optic circuits, the researchers have implemented key quantum operations such as Bell-state projections and fusion operations. These operations are crucial for applications in quantum computing and secure communication protocols.

Key Results

1. Multi-Photon Entanglement: The research demonstrates the on-chip generation of four-photon Greenberger-Horne-Zeilinger (GHZ) states and validates genuine multipartite entanglement using entanglement witness measurements. The authors report high fidelities for the generated states, such as 0.851 for the Bell state $|\Psi^-\rangle$, confirming the efficacy of the entanglement operations.
2. Quantum Teleportation: Intra-chip teleportation of single-qubit states is experimentally demonstrated with an average fidelity of 0.906 using the bosonic Bell projector. Additionally, a proof-of-concept chip-to-chip teleportation is performed over a 2-meter distance using polarization path conversion technology, achieving similar fidelities.

Implications and Future Directions

This work sets a foundational framework for scalable quantum information processing within silicon-based platforms. The ability to perform quantum teleportation between chips suggests potential for distributed quantum computing and communication networks. Future advancements could focus on improving the heralding efficiency and spectral purity by engineering resonators and implementing topologically protected photon states.

Moreover, with ongoing developments in electronic-photonic integration, silicon platforms could offer enhanced control over quantum circuits, paving the way for large-scale applications. The research also opens opportunities for exploring higher-dimensional entanglement and encoding more information per photon, which could exponentially increase computational capabilities in quantum systems.

Overall, the implications of these findings extend to quantum communication, computation, and fundamental tests of quantum physics, marking a significant step toward the integration of quantum technologies in accessible and widely used silicon platforms.