A Laboratory Frame Density Matrix for Ultrafast Quantum Molecular Dynamics

• URL: http://arxiv.org/abs/2209.11790v1
• Date: Fri, 23 Sep 2022 18:08:44 GMT
• Title: A Laboratory Frame Density Matrix for Ultrafast Quantum Molecular Dynamics
• Authors: Margaret Gregory, Simon Neville, Michael Schuurman, Varun Makhija
• Abstract summary: In most cases the ultrafast dynamics of resonantly excited molecules are considered, and almost always computed in the molecular frame. Here we provide a formalism in terms of a lab frame density matrix which connects quantum dynamics in the molecular frame to those in the laboratory frame.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: In most cases the ultrafast dynamics of resonantly excited molecules are considered, and almost always computed in the molecular frame, while experiments are carried out in the laboratory frame. Here we provide a formalism in terms of a lab frame density matrix which connects quantum dynamics in the molecular frame to those in the laboratory frame, providing a transparent link between computation and measurement. The formalism reveals that in any such experiment, the molecular frame dynamics vary for molecules in different orientations and that certain coherences which are potentially experimentally accessible are rejected by the orientation-averaged reduced vibronic density matrix. Instead, Molecular Angular Distribution Moments (MADMs) are introduced as a more accurate representation of experimentally accessible information. Furthermore, the formalism provides a clear definition of a molecular frame quantum tomography, and specifies the requirements to perform such a measurement enabling the experimental imaging of molecular frame vibronic dynamics. Successful completion of such a measurement fully characterizes the molecular frame quantum dynamics for a molecule at any orientation in the laboratory frame.

Related papers

• Simulating Chemistry with Fermionic Optical Superlattices [2.7521403951088934]
  We show that quantum number preserving Ans"atze for variational optimization in quantum chemistry find an elegant mapping to ultracold fermions in optical superlattices. Trial ground states for arbitrary molecular Hamiltonians can be prepared and their molecular energies measured in the lattice.
  arXiv  Detail & Related papers  (2024-09-09T14:35:55Z)
• Time resolved quantum tomography in molecular spectroscopy by the Maximal Entropy Approach [1.7563879056963012]
  A fundamental question emerges: what role, if any, do quantum coherences between molecular electron states play in photochemical reactions? The Maximal Entropy (MaxEnt) based Quantum State Tomography (QST) approach offers unique advantages in studying molecular dynamics. 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. We achieve a groundbreaking milestone by constructing, for the first time, the entanglement entropy of the electronic subsystem: a metric that was previously inaccessible.
  arXiv  Detail & Related papers  (2024-07-23T16:43:01Z)
• Multiple Interacting Photonic Modes in Strongly Coupled Organic Microcavities [0.0]
  We show that the emergence of a vacuum Rabi splitting in linear spectroscopy is a necessary but not sufficient metric of coherent admixing between light and matter. These vacuum-induced dissipative processes ultimately limit the extent of light-matter coherence that the system can sustain.
  arXiv  Detail & Related papers  (2024-07-06T00:50:08Z)
• Overcoming the Barrier of Orbital-Free Density Functional Theory for Molecular Systems Using Deep Learning [46.08497356503155]
  Orbital-free density functional theory (OFDFT) is a quantum chemistry formulation that has a lower cost scaling than the prevailing Kohn-Sham DFT. Here we propose M-OFDFT, an OFDFT approach capable of solving molecular systems using a deep learning functional model.
  arXiv  Detail & Related papers  (2023-09-28T16:33:36Z)
• Ultrafast Molecular Frame Quantum Tomography [0.0]
  methodology for a full molecular frame quantum tomography (MFQT) of dynamical polyatomic systems is developed. MFQT provides new routes to the study of ultrafast molecular dynamics, information processing, metrology and optimal control schemes.
  arXiv  Detail & Related papers  (2023-03-06T23:55:21Z)
• Accurate Machine Learned Quantum-Mechanical Force Fields for Biomolecular Simulations [51.68332623405432]
  Molecular dynamics (MD) simulations allow atomistic insights into chemical and biological processes. Recently, machine learned force fields (MLFFs) emerged as an alternative means to execute MD simulations. This work proposes a general approach to constructing accurate MLFFs for large-scale molecular simulations.
  arXiv  Detail & Related papers  (2022-05-17T13:08:28Z)
• Ultra-long photonic quantum walks via spin-orbit metasurfaces [52.77024349608834]
  We report ultra-long photonic quantum walks across several hundred optical modes, obtained by propagating a light beam through very few closely-stacked liquid-crystal metasurfaces. With this setup we engineer quantum walks up to 320 discrete steps, far beyond state-of-the-art experiments.
  arXiv  Detail & Related papers  (2022-03-28T19:37:08Z)
• Dispersive readout of molecular spin qudits [68.8204255655161]
  We study the physics of a magnetic molecule described by a "giant" spin with multiple $d > 2$ spin states. We derive an expression for the output modes in the dispersive regime of operation. We find that the measurement of the cavity transmission allows to uniquely determine the spin state of the qudits.
  arXiv  Detail & Related papers  (2021-09-29T18:00:09Z)
• Quantum state tomography of molecules by ultrafast diffraction [5.0544023055806235]
  We introduce a framework for the preparation and ultrafast coherent diffraction from rotational wave packets of molecules. We establish a new variant of quantum state tomography for ultrafast electron diffraction to characterize the molecular quantum states. The ability to reconstruct the density matrix of molecules of arbitrary degrees of freedom will provide us with an unprecedentedly clear view of the quantum states of molecules.
  arXiv  Detail & Related papers  (2021-07-28T12:07:56Z)
• Visualizing spinon Fermi surfaces with time-dependent spectroscopy [62.997667081978825]
  We propose applying time-dependent photo-emission spectroscopy, an established tool in solid state systems, in cold atom quantum simulators. We show in exact diagonalization simulations of the one-dimensional $t-J$ model that the spinons start to populate previously unoccupied states in an effective band structure. The dependence of the spectral function on the time after the pump pulse reveals collective interactions among spinons.
  arXiv  Detail & Related papers  (2021-05-27T18:00:02Z)
• Molecular spin qudits for quantum simulation of light-matter interactions [62.223544431366896]
  We show that molecular spin qudits provide an ideal platform to simulate the quantum dynamics of photon fields strongly interacting with matter. The basic unit of the proposed molecular quantum simulator can be realized by a simple dimer of a spin 1/2 and a spin $S$ transition metal ion, solely controlled by microwave pulses.
  arXiv  Detail & Related papers  (2021-03-17T15:03:12Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.