Monolithic semiconductor chips as a source for broadband wavelength-multiplexed polarization entangled photons

Area of Science:

• Quantum optics
• Integrated photonics
• Semiconductor device physics

Background:

• Generating entangled photons is crucial for quantum information processing (QIP).
• Ultrabroadband entangled photons are essential for advanced applications like quantum metrology and multi-party entanglement distribution.
• Existing methods often require complex off-chip components, limiting scalability.

Purpose of the Study:

• To demonstrate the direct generation of broadband wavelength-multiplexed polarization entangled photons from a monolithic semiconductor chip.
• To achieve ultrabroadband entangled photon generation without external compensation or interferometry.
• To establish a new benchmark for semiconductor waveguide sources of entangled photons.

Main Methods:

• Fabrication of a monolithic semiconductor chip for on-chip photon generation.
• Utilizing wavelength-multiplexing techniques for broadband entanglement.
• Characterization of entangled photon properties, including signal-idler separation and concurrence.

Main Results:

• Successfully generated broadband wavelength-multiplexed polarization entangled photons directly from a semiconductor chip.
• Achieved a large signal-idler spectral separation of 95 nm in the telecom band without off-chip components.
• Obtained the highest reported concurrence (0.98±0.01) for semiconductor waveguide sources.

Conclusions:

• This work presents the first direct generation of broadband entangled photons from a semiconductor chip.
• The developed on-chip source overcomes limitations of previous methods, paving the way for practical quantum technologies.
• Enables fully integrated, ultrabroadband sources for diverse quantum information processing applications.