I don't know much about quantum linear response theory but I am also trying to learn. I found a series of lecture notes by Andrei Tokmakof at MIT. This one seems to be the most relevant.
http://www.mit.edu/~tokmakof/TDQMS/Notes/8._Linear_Response_2-09.pdf.
There are two books referenced on page 20 of the notes linked to in post #2. In the book by Mazenko, section 2.1 is useful. You may also want to check the 4th chapter of Kubo's et al. book <Statistical Physics II>.
It is worth noting that this theory is very "practical", in that it allows you to figure out what you would actually MEASURE in an experiment on a quantum system.
Years ago I e.g. used it to calculate the impedance(in ohms) of a driven system (described by a JC hamiltonian) as a function of applied magnetic field, which in turn allowed me to model a particular experiment to see if it was feasible.
Very useful.
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles.
Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated...
Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/
by @RUTA
If we release an electron around a positively charged sphere, the initial state of electron is a linear combination of Hydrogen-like states. According to quantum mechanics, evolution of time would not change this initial state because the potential is time independent. However, classically we expect the electron to collide with the sphere. So, it seems that the quantum and classics predict different behaviours!
I don't know why the electrons in atoms are considered in the orbitals while they could be in sates which are superpositions of these orbitals? If electrons are in the superposition of these orbitals their energy expectation value is also constant, and the atom seems to be stable!