  We introduce a protocol addressing the conformance test problem, which
consists in determining whether a process under test conforms to a reference
one. We consider a process to be characterized by the set of end-product it
produces, which is generated according to a given probability distribution. We
formulate the problem in the context of hypothesis testing and consider the
specific case in which the objects can be modeled as pure loss channels. We
demonstrate theoretically that a simple quantum strategy, using readily
available resources and measurement schemes in the form of two-mode squeezed
vacuum and photon-counting, can outperform any classical strategy. We
experimentally implement this protocol, exploiting optical twin beams,
validating our theoretical results, and demonstrating that, in this task, there
is a quantum advantage in a realistic setting.
