Time Resolved Quantum Tomography in Molecular Spectroscopy by the Maximal Entropy Approach

Area of Science:

• Ultrafast molecular spectroscopy
• Quantum information science
• Photochemistry

Background:

• Attosecond science precisely probes initial chemical reaction moments.
• Understanding quantum coherences in electron states is crucial for photochemical reactions.

Purpose of the Study:

• To apply Maximal Entropy (MaxEnt) based Quantum State Tomography (QST) to photoexcited ammonia.
• To determine the role of quantum coherences in photochemical reactions.
• To quantify electronic entanglement entropy in molecular systems.

Main Methods:

• Developed two methodologies for constructing operator forms of observables using Molecular Angular Distribution Moments (MADMs) and Angular Momentum Coherence Operators.
• Applied MaxEnt-based QST to photoexcited ammonia with partial tomographic data.
• Visualized electron density and charge migration within the molecular frame.

Main Results:

• Established a direct link between Lagrange multipliers in MaxEnt and MADMs.
• Successfully visualized charge migration in photoexcited ammonia.
• Quantified electronic entanglement entropy for the first time, revealing electron-nuclear coupling effects.

Conclusions:

• MaxEnt-based QST is effective for studying molecular dynamics, even with partial data.
• The developed methods enable visualization of electron density and quantification of entanglement.
• Findings advance ultrafast molecular spectroscopy and quantum information science applications in studying excited molecular systems.