We propose a simple method for measuring the populations and the relative phase in a coherent superposition of two atomic states. The method is based on coupling the two states to a third common (excited) state by means of two laser pulses, and measuring the total fluorescence from the third state for several choices of the excitation pulses.
@article{arxiv.quant-ph/9906051,
title = {Measuring a coherent superposition},
author = {N. V. Vitanov and B. W. Shore and R. G. Unanyan and K. Bergmann},
journal= {arXiv preprint arXiv:quant-ph/9906051},
year = {2009}
}