We propose a detection scheme for measuring the overlap of the quantum state of a weakly excited traveling-field mode with a desired reference quantum state, by successive mixing the signal mode with modes prepared in coherent states and performing photon-number measurements in an array of beam splitters. To illustrate the scheme, we discuss the measurement of the quantum phase and the detection of Schrodinger-cat-like states.
@article{arxiv.quant-ph/9910029,
title = {Measuring quantum state overlaps of traveling optical fields},
author = {J. Clausen and M. Dakna and L. Knoll and D. -G. Welsch},
journal= {arXiv preprint arXiv:quant-ph/9910029},
year = {2016}
}