Ultrafast molecular dynamics in terahertz-STM experiments: Theoretical analysis using Anderson-Holstein model

Abstract

We analyze ultrafast tunneling experiments in which electron transport through a localized orbital is induced by a single cycle THz pulse. We include both electron-electron and electron-phonon interactions on the localized orbital using the Anderson-Holstein model and consider two possible filling factors, the singly occupied Kondo regime and the doubly occupied regime relevant to recent experiments with a pentacene molecule. Our analysis is based on variational non-Gaussian states and provides the accurate description of the degrees of freedom at very different energies, from the high microscopic energy scales to the Kondo temperature $T_K$. To establish the validity of the new method we apply this formalism to study the Anderson model in the Kondo regime in the absence of coupling to phonons. We demonstrate that it correctly reproduces key properties of the model, including the screening of the impurity spin, formation of the resonance at the Fermi energy, and a linear conductance of $2e^2/h$. We discuss the suppression of the Kondo resonance by the electron-phonon interaction on the impurity site. When analyzing THz STM experiments we compute the time dependence of the key physical quantities, including current, the number of electrons on the localized orbital, and the number of excited phonons. We find long-lived oscillations of the phonon that persist long after the end of the pulse. We compare the results for the interacting system to the non-interacting resonant level model.

24 pages, 12 figures

References in corpus (25)

• Continuous-time Monte Carlo methods for quantum impurity models
• The numerical renormalization group method for quantum impurity systems
• Quantum Criticality in Heavy Fermion Metals
• Electrodynamics of Correlated Electron Materials
• Molecular Transport Junctions: Vibrational Effects
• Heavy Fermions and Quantum Phase Transitions
• Real-time dynamics in Quantum Impurity Systems: A Time-dependent Numerical Renormalization Group Approach
• Time-Dependent Mean Field Theory for Quench Dynamics in correlated electron systems
• Tuning the Kondo effect with a mechanically controllable break junction
• Real-time simulations of nonequilibrium transport in the single-impurity Anderson model
• Nagaoka ferromagnetism observed in a quantum dot plaquette
• Vibrational Sidebands and Kondo-effect in Molecular Transistors
• Evolution of the Kondo Effect in a Quantum Dot Probed by the Shot Noise
• Variational study of U(1) and SU(2) lattice gauge theories with Gaussian states in 1+1 dimensions
• Enhanced electron-phonon coupling in graphene with periodically distorted lattice
• Exploring the Kondo model in and out of equilibrium with alkaline-earth atoms
• Electron-phonon coupling and charge gap in spin-density-wave iron-pnictides from quasiparticle relaxation dynamics
• Solving quantum impurity problems in and out of equilibrium with variational approach
• Shot noise near the unitary limit of a Kondo quantum dot
• Ultrafast dynamics of spin and orbital correlations in quantum materials: an energy- and momentum-resolved perspective
• Quantum Rydberg Central Spin Model
• Variational principle for quantum impurity systems in and out of equilibrium: application to Kondo problems
• Projective Quantum Monte Carlo Method for the Anderson Impurity Model and its Application to Dynamical Mean Field Theory
• Microscopic theory of resonant soft x-ray scattering in systems with charge order
• Efficient variational approach to dynamics of a spatially extended bosonic Kondo model

Cited by in corpus (7)

• Atomic-Scale Terahertz Near Fields for Ultrafast Tunnelling Spectroscopy
• Zero-Temperature Phases of the 2D Hubbard-Holstein Model: A Non-Gaussian Exact Diagonalization Study
• A variational approach for many-body systems at finite temperature
• Fluctuating Nature of Light-Enhanced $d$-Wave Superconductivity: A Time-Dependent Variational Non-Gaussian Exact Diagonalization Study
• Quantum impurity models using superpositions of fermionic Gaussian states: Practical methods and applications
• A Hybrid Quantum-Classical Method for Electron-Phonon Systems
• Charge density wave breakdown in a heterostructure with electron-phonon coupling