Adiabatic Transitions in a Two-Level System Coupled to a Free Boson Reservoir

In this chapter we study with the tools developed in Chapter 3 the basic models that are the foundations of light–matter interaction. We start with Rabi dynamics, then consider the optical Bloch equations that add phenomenologically the lifetime of the populations. As decay and pumping are often important, we cover the Lindblad form, a correct, simple and powerful way to describe various dissipation mechanisms. Then we go to a full quantum picture, quantizing also the optical field. We first investigate the simpler coupling of bosons and then culminate with the Jaynes–Cummings model and its solution to the quantum interaction of a two-level system with a cavity mode. Finally, we investigate a broader family of models where the material excitation operators differ from the ideal limits of a Bose and a Fermi field.

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Revealing the nonlinear response of a tunneling two-level system ensemble using coupled modes

Physical Review Materials ◽

10.1103/physrevmaterials.1.012601 ◽

2017 ◽

Vol 1 (1) ◽

Cited By ~ 7

Author(s):

Naftali Kirsh ◽

Elisha Svetitsky ◽

Alexander L. Burin ◽

Moshe Schechter ◽

Nadav Katz

Keyword(s):

Nonlinear Response ◽

Level System ◽

Coupled Modes

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Density matrix and purity evolution in dissipative two-level systems: II. Relaxation

Physical Chemistry Chemical Physics ◽

10.1039/d0cp05528j ◽

2021 ◽

Author(s):

Sambarta Chatterjee ◽

Nancy Makri

Keyword(s):

Density Matrix ◽

Time Evolution ◽

Reduced Density Matrix ◽

Level System ◽

Two Level Systems ◽

Reduced Density ◽

Harmonic Bath

We investigate the time evolution of the reduced density matrix (RDM) and its purity in the dynamics of a two-level system coupled to a dissipative harmonic bath, when the system is initially placed in one of its eigenstates.

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Comparison of the Performances of Different Computational Methods to Calculate the Electrochemical Stability of Selected Ionic Liquids

Materials ◽

10.3390/ma14123221 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3221

Author(s):

Annalisa Paolone ◽

Sergio Brutti

Keyword(s):

Ionic Liquids ◽

Density Functional ◽

Quantitative Agreement ◽

Electrochemical Stability ◽

Functional Theory ◽

Molecular Systems ◽

Reduction Potentials ◽

Adiabatic Transitions ◽

Alkyl Ammonium ◽

Transition Scheme

The electrochemical stability windows (ESW) of selected ionic liquids have been calculated by comparing different computational approaches previously suggested in the literature. The molecular systems under study are based on di-alkyl imidazolium and tetra-alkyl ammonium cations coupled with two different imide anions (namely, bis-fluorosulfonyl imide and bis-trifluoromethyl sulfonyl imide), for which an experimental investigation of the ESW is available. Thermodynamic oxidation and reduction potentials have here been estimated by different models based on calculations either on single ions or on ionic couples. Various Density Functional Theory (DFT) functionals (MP2, B3LYP, B3LYP including a polarizable medium and empirical dispersion forces) were exploited. Both vertical and adiabatic transitions between the starting states and the oxidized or reduced states were considered. The approach based on calculations on ionic couples is not able to reproduce the experimental data, whatever the used DFT functional. The best quantitative agreement is obtained by calculations on single ions when the MP2 functional in vacuum is considered and the transitions between differently charged states are vertical (purely electronic without the relaxation of the structure). The B3LYP functional underestimates the ESW. The inclusion of a polar medium excessively widens the ESW, while a large shrinkage of the ESW is obtained by adopting an adiabatic transition scheme instead of a vertical transition one.

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