Quantum CZ gates on a single gradient metasurface

Area of Science:

• Quantum optics
• Nanophotonics
• Quantum information science

Background:

• On-chip quantum information processing requires efficient integration of quantum gates.
• Metasurfaces offer novel functionalities for manipulating light at the nanoscale.

Purpose of the Study:

• To propose a scheme for realizing quantum controlled-Z (CZ) gates using a single gradient metasurface.
• To explore the potential for high-density and multifunctional integration of quantum devices.

Main Methods:

• Utilizing the parallel beam-splitting feature of a gradient metasurface.
• Implementing polarization encoding and path encoding for CZ gates.
• Leveraging the locking of output path by input polarization to filter errors.

Main Results:

• A single metasurface can support polarization-encoded CZ gates, path-encoded CZ gates, multiple independent CZ gates, and cascaded CZ gates.
• Path-encoded CZ gates effectively filter bit-flip errors from beam-splitting.
• The proposed CZ gates can detect quantum errors and generate high-dimensional entanglement.

Conclusions:

• Integrating quantum CZ gates onto a single metasurface facilitates high-density and multifunctional quantum photonic integration.
• This work opens new avenues for advanced on-chip quantum information processing.
• Metasurface-based quantum gates offer enhanced error resilience and entanglement generation capabilities.