It seems like (controlled) noise can sometimes be good: dithering in an image, or a softer sound in audio, or white noise alone. Here's a paper on noise improving detectability. My intuition also says that noise in a financial trading algorithm could act as a sort of hedge.
I have few examples — only a vague philosophical instinct. Is there any general-purpose literature or theory on why and how noise can be good? Or other/better examples?