Optimization of two-photon wave function in parametric down conversion by adaptive optics control of the pump...

Area of Science:

• Quantum optics
• Nonlinear optics
• Photonics

Background:

• Spontaneous parametric down-conversion (SPDC) is a key process for generating entangled photons.
• Controlling the spatial profile of entangled photons is crucial for many quantum information applications.
• Optimizing the wave function's spatial characteristics can improve the efficiency and fidelity of quantum states.

Purpose of the Study:

• To present an efficient method for optimizing the spatial profile of entangled-photon wave functions generated via SPDC.
• To demonstrate precise control over the joint biphoton wave function's spatial characteristics.
• To enhance two-photon coupling into specific spatial modes for correlated detection.

Main Methods:

• Utilizing a deformable mirror to modify the wavefront of a continuous-wave (CW) diode laser pump.
• Employing a nonlinear β-barium borate (BBO) type-I crystal for the SPDC process.
• Implementing a feedback loop using the biphoton coincidence rate to guide the optimization of the wavefront shape.

Main Results:

• Successfully controlled and optimized the spatial profile of the joint biphoton wave function.
• Achieved efficient coupling of two-photon states into single spatial modes.
• Demonstrated the practical application of the developed optimization technique.

Conclusions:

• The deformable mirror-based wavefront optimization is an effective method for controlling entangled-photon spatial profiles.
• This technique offers a practical approach to enhance two-photon coupling for applications in quantum optics and information.
• The results pave the way for improved generation and manipulation of entangled photon states.