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4: Characterizing Fluctuations

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    • 4.1: Eigenstate vs. system/bath perspectives
      From our earlier work on electronic spectroscopy, we found that there are two equivalent ways of describing spectroscopic problems, which can be classified as the eigenstate and system/bath perspectives. Let’s summarize these before turning back to nonlinear spectroscopy.
    • 4.2: Energy Gap Fluctuations
      How do transition energy gap fluctuations enter into the nonlinear response? As we did in the case of linear experiments, we will make use of the second cumulants approximation to relate dipole correlation functions to the energy gap correlation function .
    • 4.3: Nonlinear Response with the Energy Gap Hamiltonian
      In a manner that parallels our description of the linear response from a system coupled to a bath, the nonlinear response can also be partitioned into a system, bath and energy gap Hamiltonian, leading to similar averages over the fluctuations of the energy gap.
    • 4.4: How Can you Characterize Fluctuations and Spectral Diffusion?

    This page titled 4: Characterizing Fluctuations is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Andrei Tokmakoff via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.