Physics: Fermi's golden rule

Nuclear & Particle Quantum Mechanics
Fermi's golden rule In quantum physics, Fermi's golden rule is a formula that describes the transition rate (the probability of a transition per unit time) from one energy eigenstate of a quantum system to a group of energy eigenstates in a continuum, as a result of a weak perturbation.

Commentary

Commentary

Source: Wikipedia
Fermi's golden rule In quantum physics, Fermi's golden ru le is a formula that describes the transition rate (the probability of a transition per unit time) from one energy eigenstate of a quantum system to a group of energy eigenstates in a continuum, as a result of a weak perturbation.

Commentary

Source: Internal
Why does Fermi's golden rule matter? This princip le is one of the building blocks physicists use to explain the world. Without it, a whole class of phenomena would have no mathematical description. Engineers, chemists, and astronomers all rely on it.

Commentary

Source: Wikipedia
Background: Fermi's golden rule In quantum physics, Fermi's golden rule is a formula that describes the transition rate (the probability of a transition per unit time) from one energy eig enstate of a quantum system to a group of energy eigenstates in a continuum, as a result of a weak perturbation. This transition rate is effectively independent of time (so long as the strength of the perturbation is independent of time) and is proportional to the strength of the coupling between the initial and final states of the system (described by the square of the matrix element of the perturbation) as well as the density of states. It is also applicable when the final state is discrete, i.e. it is not part of a continuum, if there is some decoherence in the process, like relaxation or collision of the atoms, or like noise in the perturbation, in which case the density of states is replaced by the reciprocal of the decoherence bandwidth.