Multidimensional quantum entanglement with large-scale integrated optics

Abstract: The ability to control multidimensional quantum systems is key for the investigation of fundamental science and for the development of advanced quantum technologies. Here we demonstrate a multidimensional integrated quantum photonic platform able to robustly generate, control and analyze high-dimensional entanglement. We realize a programmable bipartite entangled system with dimension up to $15 \times 15$ on a large-scale silicon-photonics quantum circuit. The device integrates more than 550 photonic components on a single chip, including 16 identical photon-pair sources. We verify the high precision, generality and controllability of our multidimensional technology, and further exploit these abilities to demonstrate key quantum applications experimentally unexplored before, such as quantum randomness expansion and self-testing on multidimensional states. Our work provides a prominent experimental platform for the development of multidimensional quantum technologies.

• The paper introduces a scalable silicon-photonics platform that generates high-dimensional entangled states using 16 photon-pair sources.
• It details universal operations and high-fidelity projective measurements on qudits via integrated linear-optical circuits.
• The work validates multidimensional quantum protocols, including Bell non-locality tests and device-independent randomness expansion.

Overview of Multidimensional Quantum Entanglement with Large-Scale Integrated Optics

This paper explores the development and capabilities of a multidimensional integrated quantum photonic platform designed for generating, controlling, and analyzing high-dimensional quantum entanglement. The researchers demonstrate a programmable bipartite system with dimensions up to 15 × 15 on a silicon-photonics quantum circuit, integrating more than 550 photonic components, including 16 photon-pair sources. This work highlights the platform's precision, versatility, and control in executing complex quantum tasks such as multidimensional quantum randomness expansion and state self-testing, providing a robust foundation for multidimensional quantum technologies.

Key Contributions

1. High-Dimensional Entangled State Generation: The paper presents a methodology for generating entangled states using a coherent and controllable excitation of an array of photon-pair sources. This approach demonstrates the ability to arbitrarily control the degree of entanglement across multiple dimensions.
2. Multidimensional Operations and Measurements: The platform can perform universal operations on path-encoded qudits using integrated linear-optical circuits. The system is capable of high-fidelity projective measurements in various bases, achieving excellent statistical fidelities across multiple dimensions, with decreasing fidelity observed with increasing dimension.
3. Quantum Information Protocols: The platform's capabilities enable exploring quantum protocols that were previously experimentally unexplored in multidimensional settings. This includes demonstrating multidimensional Bell non-locality and device-independent (DI) self-testing using new classes of Bell inequalities optimized for maximally entangled states.
4. Randomness Expansion: The paper details the use of the platform for generating randomness, a critical quantum resource. It leverages both fully device-independent (DI) and one-sided DI scenarios for randomness expansion, illustrating higher dimensions' potential for efficient randomness generation per measurement round.

Implications and Future Developments

The integrated photonic platform represents a significant advancement in quantum photonics by offering a scalable, precise, and programmable solution for multidimensional quantum systems. The potential applications are considerable, ranging from secure communications, such as enhanced quantum key distribution (QKD) protocols benefiting from multidimensional encoding, to complex information processing tasks in quantum computing and simulation.

The presented technology could pave the way for scalable quantum networks, particularly as techniques for inter-chip state distribution mature. The system's dimensionality and control are likely expandable with further advances in photonic integration, potentially allowing for more complex quantum interactions and entanglement across more substantial numbers of photons and modes.

Conclusion

The research presented in this paper offers a comprehensive exploration of a cutting-edge quantum photonic integrated platform, emphasizing its utility in generating and manipulating high-dimensional quantum states. The ability to perform unprecedented quantum tasks onsite with such precision underscores integrated optics' crucial role in advancing scalable and practical quantum technologies. These developments hold promise for elevating the field of quantum information science towards a wide range of achievable applications and deeper understanding of quantum phenomena in higher dimensions.