Atomic electron transitions cause the emission or absorption of
photons. Their statistics are
Poissonian, and the time between jumps is
exponentially distributed. The damping time constant (which ranges from
nanoseconds to a few seconds) relates to the natural, pressure, and field
broadening of spectral lines. The larger the energy separation of the states between which the electron jumps, the shorter the
wavelength of the photon emitted. In an
ion trap, quantum jumps can be directly observed by addressing a trapped ion with radiation at two different frequencies to drive electron transitions. This requires one strong and one weak transition to be excited (denoted \omega12 and \omega13 respectively in the figure to the right). The electron energy level, |2\rangle, has a short lifetime, \Gamma2 which allows for constant emission of photons at a frequency \omega12 which can be collected by a camera and/or
photomultiplier tube. State |3\rangle has a relatively long lifetime \Gamma3 which causes an interruption of the photon emission as the electron gets shelved in state through application of light with frequency \omega13. The ion going dark is a direct observation of quantum jumps. == Molecular electronic transition ==