Manipulating Two-Photon Absorption of Molecules through Efficient Optimization of Entangled Light

Area of Science:

• Quantum optics
• Molecular spectroscopy
• Nonlinear optics

Background:

• Pulsed entangled photons from parametric downconversion offer unique temporal and spectral properties.
• Two-photon absorption (TPA) is a nonlinear optical process crucial for various applications.
• Selective excitation of molecular electronic states is challenging with classical light.

Purpose of the Study:

• To develop a comprehensive optimization protocol for manipulating electronic excitations using entangled photons.
• To enhance entangled two-photon absorption (eTPA) probability in molecular systems.
• To explore the potential of eTPA for selective excitation and applications in molecular systems like thiophene dendrimers.

Main Methods:

• Development of a Bayesian optimization protocol for spectral phase optimization.
• Utilizing pulsed entangled photons from a parametric downconversion source.
• Investigating eTPA in the small entanglement time limit.
• Application to a thiophene dendrimer system.

Main Results:

• Achieved up to a 20-fold enhancement in eTPA probability for a thiophene dendrimer.
• Demonstrated that classical light is non-optimizable for this process.
• Showcased selective excitation capabilities not achievable with classical light.
• Observed excitation of molecular electronic states with vanishingly small probabilities for classical light in the small entanglement time limit.

Conclusions:

• Entangled photons and Bayesian optimization provide a powerful tool for manipulating electronic excitations.
• eTPA offers significant advantages over classical light for enhancing absorption probabilities and achieving selective excitation.
• The developed protocol and findings have direct implications for advanced molecular spectroscopy and quantum information applications.