Abstract

Laser-cooled ions stored in Penning traps are essentially free from collisions and other perturbations that could cause relaxations. This, and the fact that their energy levels can easily be manipulated with rf and laser radiation, makes them well suited for demonstrating certain aspects of quantum measurement theory. The quantum Zeno effect is the inhibition of transitions between states by frequent measurements.¹ We have observed this effect in a ⁹Be⁺ ground-state rf transition. The measurements are short pulses of light. If the ion is in one state, it scatters a few photons; if it is in the other, it scatters no photons. In the latter case the wavefunction collapse is due to a null measurement.² The dynamics of this system are similar to those which are predicted to lead to nonexponential spontaneous decay at short times.

© 1989 Optical Society of America