Perspectives of an experiment for detecting macroscopic quantum coherence

In the second half of 1993 we presented to INFN a proposal of an experiment for detecting macroscopic quantum coherence with a system of SQUIDs. It wa s based essentially on ideas presented first by Leggett and collaborators a nd developed in many articles in the 1980s. The experimental work started i n the 1994 just after the approval of the INFN. As an introduction, the exp erimental method and the setup we choose in order to perform a set of measu rements on a system of SQUIDs is described. Then the measuring procedures a nd their purposes are explained and discussed. As a future perspective, a possible test on the existence of the quantum gr avity is discussed. According to a theoretical proposal by John Ellis and c ollaborators, the quantum gravitational "friction" could induce the transit ion from QM behavior of microscopic states to the classical behavior of mac roscopic states, i.e., states containing an Avogadro number (M-pl/M-e) of e lementary particles, as may be obtained in a SQUID.