Programmable time-frequency mode-sorting of single photons with a multi-output quantum pulse gate.

Area of Science:

• Quantum Information Science
• Photonics
• Quantum Communication

Background:

• High-dimensional encoding is crucial for increasing quantum communication capacity.
• Existing mode-sorters often lack programmability and flexibility in handling various temporal modes.
• Single-photon level manipulation is essential for practical quantum information processing.

Purpose of the Study:

• To demonstrate a novel high-dimensional mode-sorter for single photons.
• To enable dynamic switching between different temporal-mode encodings.
• To advance the practical implementation of quantum information applications.

Main Methods:

• Utilized a multi-output quantum pulse gate for mode-sorting.
• Programmed the device to switch between pulse modes, frequency bins, time bins, and superpositions.
• Characterized the mode-sorter using detector tomography in 3 and 5 dimensions.

Main Results:

• Achieved a high-dimensional mode-sorter for single photons.
• Demonstrated programmability to switch between diverse temporal-mode encodings.
• Obtained a high fidelity of up to 0.958 ± 0.030 at the single-photon level.

Conclusions:

• The developed quantum pulse gate serves as a versatile high-dimensional mode-sorter.
• This technology facilitates practical quantum key distribution with enhanced information capacity.
• The device shows significant potential for secure communication and advanced quantum information applications.