Nonlinear molecular spectroscopy

Sum-of-states (SOS) for multilevel system

Computationally cheap and intuitive.

Note

In the SOS method, dissipation and decoherence are introduced phenomelogically.

Correlation function approach

Direct computing the many-point correlation functions with the quantum regression theorem

• Closed quantum systems

• Open quantum systems

  Valid for open quantum systems where environment effects can be rigirously described with quantum master equations.

  Visulize with double-sided Feynman diagrams instead of the time-loop diagrams.

• Many-body systems

  Solve Dyson equaiton for one-particle Green’s function

  \[G = G_0 + G_0 \Sigma G\]

Non-perturbative approah

valid for ALL systems if a quantum dynamics solver is provided.

Simulating the laser-driven dynamics including explicitly all laser pulses. This usually requires phase clcyling to remove unwanted pathways.