Time resolved quantum tomography in molecular spectroscopy by the Maximal Entropy Approach

Fuente: arXiv
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Auteurs principaux: Makhija, Varun, Gupta, Rishabh, Neville, Simon, Schuurman, Micheal, Francisco, Joseph, Kais, Sabre
Format: Preprint
Publié: 2024
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author Makhija, Varun
Gupta, Rishabh
Neville, Simon
Schuurman, Micheal
Francisco, Joseph
Kais, Sabre
author_facet Makhija, Varun
Gupta, Rishabh
Neville, Simon
Schuurman, Micheal
Francisco, Joseph
Kais, Sabre
contents Attosecond science offers unprecedented precision in probing the initial moments of chemical reactions, revealing the dynamics of molecular electrons that shape reaction pathways. A fundamental question emerges: what role, if any, do quantum coherences between molecular electron states play in photochemical reactions? Answering this question necessitates quantum tomography: the determination of the electronic density matrix from experimental data, where the off-diagonal elements represent these coherences. The Maximal Entropy (MaxEnt) based Quantum State Tomography (QST) approach offers unique advantages in studying molecular dynamics, particularly with partial tomographic data. Here, we explore the application of MaxEnt-based QST on photoexcited ammonia, necessitating the operator form of observables specific to the performed measurements. We present two methodologies for constructing these operators: one leveraging Molecular Angular Distribution Moments (MADMs) which accurately capture the orientation-dependent vibronic dynamics of molecules; and another utilizing Angular Momentum Coherence Operators to construct measurement operators for the full rovibronic density matrix in the symmetric top basis. A key revelation of our study is the direct link between Lagrange multipliers in the MaxEnt formalism and the unique set of MADMs. Furthermore, we achieve a groundbreaking milestone by constructing, for the first time, the entanglement entropy of the electronic subsystem: a metric that was previously inaccessible. The entropy vividly reveals and quantifies the effects of coupling between the excited electron and nuclear degrees of freedom. Consequently, our findings open new avenues for research in ultrafast molecular spectroscopy within the broader domain of quantum information science.
format Preprint
id arxiv_https___arxiv_org_abs_2407_16630
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Time resolved quantum tomography in molecular spectroscopy by the Maximal Entropy Approach
Makhija, Varun
Gupta, Rishabh
Neville, Simon
Schuurman, Micheal
Francisco, Joseph
Kais, Sabre
Chemical Physics
Quantum Physics
Attosecond science offers unprecedented precision in probing the initial moments of chemical reactions, revealing the dynamics of molecular electrons that shape reaction pathways. A fundamental question emerges: what role, if any, do quantum coherences between molecular electron states play in photochemical reactions? Answering this question necessitates quantum tomography: the determination of the electronic density matrix from experimental data, where the off-diagonal elements represent these coherences. The Maximal Entropy (MaxEnt) based Quantum State Tomography (QST) approach offers unique advantages in studying molecular dynamics, particularly with partial tomographic data. Here, we explore the application of MaxEnt-based QST on photoexcited ammonia, necessitating the operator form of observables specific to the performed measurements. We present two methodologies for constructing these operators: one leveraging Molecular Angular Distribution Moments (MADMs) which accurately capture the orientation-dependent vibronic dynamics of molecules; and another utilizing Angular Momentum Coherence Operators to construct measurement operators for the full rovibronic density matrix in the symmetric top basis. A key revelation of our study is the direct link between Lagrange multipliers in the MaxEnt formalism and the unique set of MADMs. Furthermore, we achieve a groundbreaking milestone by constructing, for the first time, the entanglement entropy of the electronic subsystem: a metric that was previously inaccessible. The entropy vividly reveals and quantifies the effects of coupling between the excited electron and nuclear degrees of freedom. Consequently, our findings open new avenues for research in ultrafast molecular spectroscopy within the broader domain of quantum information science.
title Time resolved quantum tomography in molecular spectroscopy by the Maximal Entropy Approach
topic Chemical Physics
Quantum Physics
url https://arxiv.org/abs/2407.16630