Single-photon diode by exploiting the photon polarization in a waveguide.

Area of Science:

• Quantum optics
• Solid-state physics
• Nanophotonics

Background:

• Single-photon devices are essential for quantum information processing.
• Achieving efficient and robust optical diodes at the quantum level remains a challenge.
• Existing methods often require active components or specific conditions.

Purpose of the Study:

• To demonstrate a practical single-photon optical diode.
• To utilize quantum impurity coupling in a passive waveguide for unidirectional photon propagation.
• To analyze the performance and robustness of such a device.

Main Methods:

• Coupling a quantum impurity to a passive, linear optical waveguide.
• Exploiting a waveguide with locally planar, circular polarization.
• Analyzing photon propagation and contrast using theoretical models.
• Investigating the effect of finite frequency bandwidth and impurity dissipation.

Main Results:

• A single-photon optical diode was successfully demonstrated.
• Near-unitary contrast was achieved for broadband single-photon pulses.
• The device performance is independent of the quantum impurity's intrinsic dissipation.
• The concept is applicable to various waveguide types.

Conclusions:

• A robust and efficient single-photon optical diode can be realized by coupling quantum impurities to specifically designed waveguides.
• This approach offers a promising pathway for building essential components for quantum communication and computation.
• The insensitivity to dissipation simplifies practical implementation and enhances device reliability.