Ultracompact 3D integrated photonic chip for high-fidelity high-dimensional quantum gates

Area of Science:

• Quantum optics
• Photonic integrated circuits
• High-dimensional quantum information processing

Background:

• Spatial modes of photons are crucial for encoding information in quantum computing.
• Multiplane light conversion (MPLC) is a technique for manipulating spatial light modes.
• Existing methods often lack compactness and integration capabilities.

Purpose of the Study:

• To demonstrate a polymer-based MPLC device for high-dimensional quantum logic gates.
• To fabricate an ultracompact device using femtosecond laser 3D printing.
• To integrate spatial mode manipulation into a miniaturized photonic platform.

Main Methods:

• Fabrication of a polymer-based MPLC device using femtosecond laser 3D printing.
• Design of a 3D Hadamard quantum logic gate via a trained diffractive neural network.
• Evaluation using quantum process tomography at the single-photon level.

Main Results:

• Achieved a 90% fidelity for the 3D Hadamard gate at the single-photon level.
• Demonstrated an ultracompact device for spatial mode manipulation.
• Successfully integrated spatial mode control into a miniaturized photonic platform.

Conclusions:

• Polymer-based MPLC is feasible for compact quantum logic implementation.
• This approach enables scalable, high-dimensional quantum information processing.
• The technology paves the way for advanced integrated photonic quantum circuits.