Possibility of Direct Observation of Quantum Jumps

In a single-atom double-resonance experiment involving a strong and a weak transition, quantum jumps on the weak transition cause the fluorescence of the strong transition to turn on and off abruptly. The fluorescence is off when the weak transition is excited and on when it is not. Thus quantum jumps on the weak transition can be directly monitored by observation of the random telegraph signal radiated by the strong transition. We present here a simple theory of this effect for the case of incoherent excitation.