analyzing in which sense WVA can be useful. On the one hand, the technique generally makes use of linear-optics unitary operations. Therefore, it cannot modify the statistics of photons involved. Basic quantum estimation theory states that the post-selection of an appropriate output state, the basic element in WVA, cannot be better than the use of the input state [@nielsen2000]. Moreover, WVA uses some selected, appropriate but partial, information about the quantum state that cannot be better that considering the full state. Indeed, due to the unitarian nature of the operations involved, it should be equally good any transformation of the input state than performing no transformation at all. In other words, when considering only the quantum nature of the light used, WVA cannot enhance the precision of measurements [@lijian2015].

On the other hand, a more general analysis that goes beyond only considering the quantum nature of the light, shows that WVA can be useful when certain technical limitations are considered. In this sense, it might increase the ultimate resolution of the detection system by effectively lowering the value of the smallest quantity that can detected. In most scenarios, although not always [@torres2012], the signal detected is severely depleted, due to 