Beyond the standard quantum limit

A fundamental peculiarity of gravitational waves is the fact that they couple very weakly to the matter. For this reason the response of a detector can be so small to be comparable with quantum undeterminations. An important limitation for the sensitivity of future generation interferometric detectors of gravitational waves is the so-called standard quantum limit, which makes impossible to do repeated, arbitrary precision measurements of the relevant observables. It can be explained as the consequence of the measurement process´ back action on the detector´s dynamics. A relevant theoretical and experimental effort has been done in these years in order to study the possibility of avoiding this limitation, which is no more considered a fundamental one. In this talk after a short introduction to the SQL problem from a general point of view I discuss some proposals for detection strategies designed to evade it.