Maximally Efficient Biphoton Generation by Single Photon Decay in Nonlinear Quantum Photonic Circuits

Area of Science:

• Quantum optics
• Nonlinear photonics
• Integrated optics

Background:

• Parametric down-conversion is a key source of quantum-correlated photons.
• Achieving high generation efficiency in nonlinear optical processes is challenging.
• Existing methods often lack a general theoretical framework for optimization.

Purpose of the Study:

• To develop a general nonperturbative formalism for biphoton generation.
• To propose an optimized scheme for maximally efficient biphoton state creation.
• To establish a fundamental efficiency limit for nonlinear quantum photon generation.

Main Methods:

• General nonperturbative formalism.
• Extension of the critical coupling concept to nonlinear photon mode coupling.
• Analysis of single-photon nonlinearity.

Main Results:

• A generalized critical coupling concept for optimal single-photon nonlinearity.
• A fundamental upper limit on nonlinear generation efficiency for quantum-correlated photons.
• Efficiency approaching unity under low-loss conditions.

Conclusions:

• The developed formalism provides a pathway to maximally efficient biphoton generation.
• The critical coupling generalization offers a new perspective on optimizing nonlinear quantum processes.
• Low absorption losses are crucial for approaching the theoretical efficiency limit.