Quantum computers, which operate leveraging quantum mechanics effects, could soon outperform traditional computers in some advanced optimization and simulation tasks. Most quantum computing systems developed so far store and process information using qubits (quantum units of information that can exist in a superposition of two states).

In recent years, however, some physicists and engineers have been trying to develop quantum computers based on qudits, multi-level units of quantum information that can hold more than two states.

Qudit-based quantum systems could store more information and perform computations more efficiently than qubit-based systems, yet they are also more prone to decoherence.

A recent study has realized multipartite entanglement on an optical chip for the first time, constituting a significant advance for scalable quantum information. The paper, titled “Continuous-variable multipartite entanglement in an integrated microcomb,” is published in Nature.

Led by Professor Wang Jianwei and Professor Gong Qihuang from the School of Physics at Peking University, in collaboration with Professor Su Xiaolong’s research team from Shanxi University, the research has implications for quantum computation, networking and metrology.

Continuous-variable integrated quantum photonic chips have been confined to the encoding of and entanglement between two qumodes, a bottleneck withholding the generation or verification of multimode entanglement on chips. Additionally, past research on cluster states failed to go beyond discrete viable, leaving a gap in the generation and detection of continuous-variable entanglement on photonic chips.

Combining on-chip photon-pair sources, two sets of linear integrated circuits for path entanglements and two path-to-orbital angular momentum converters, free-space-entangled orbital angular momentum photon pairs can be generated in high-dimensional vortex states, offering a high level of programmable dynamical reconfigurability.