And I suppose ##c=1##?Einj said:
Fermi Golden Rule is a fundamental principle in quantum mechanics that describes the transition rate between two quantum states due to a perturbing Hamiltonian. It is named after Italian physicist Enrico Fermi.
Fermi Golden Rule is important because it helps us understand and calculate the probability of transitions between quantum states, which is essential in many areas of physics, such as quantum optics, solid state physics, and nuclear physics.
Fermi Golden Rule is derived from the time-dependent perturbation theory in quantum mechanics. It involves calculating the transition matrix elements between the initial and final states, and then taking the square of the absolute value of this matrix element.
The main assumptions made in Fermi Golden Rule are that the perturbing Hamiltonian is small compared to the unperturbed Hamiltonian, and that the perturbation is turned on and off slowly enough so that the system has time to reach a steady state.
Fermi Golden Rule is applied in a wide range of practical applications, such as calculating the rate of spontaneous emission in atoms, the rate of energy transfer in molecular systems, and the rate of nuclear decay. It is also used in the design of quantum devices and technologies.