Scientists at Tsinghua University and Hefei National Laboratory have created a new way to link smaller entangled microwave photon groups into larger, adjustable quantum states.

Researchers at Tsinghua University and Hefei National Laboratory have introduced a strategy to connect smaller entangled groups of microwave photons into larger, reconfigurable graph states. Published in Nature Physics, the approach utilizes a superconducting circuit to perform deterministic fusion. The team successfully demonstrated this method by creating genuine multipartite entanglement across 13 photonic qubits.

Deterministic fusion via superconducting circuits

Conventional fusion methods for building large graph states often rely on optical components like mirrors and beam splitters, which are probabilistic and frequently require repeated attempts. To address this, the research team employed a quantum non-demolition detector to perform parity measurements on photon pairs. This process entangles the photons without destroying them, allowing for the connection of smaller graph states into larger ones. The researchers used frequency tuning to select which photons to fuse, providing a programmable and nondestructive operation. This architecture allows for the scaling of photonic graph states by joining smaller, on-demand resource states.

Future applications and development

The ability to generate large, adjustable graph states is considered a significant resource for quantum communication, quantum networks, and measurement-based quantum computing. The researchers noted that this work could eventually contribute to the development of more sophisticated quantum processors and long-distance quantum communication networks. Moving forward, the team plans to improve device fidelity, photon-generation efficiency, and detector performance. They also aim to develop multidetector architectures capable of performing more fusion operations to generate even larger, higher-dimensional graph states.