Metrology is the science of estimations and measurements. We are used to dealing with probabilities that range from 0% (never happens) to 100% (always happens). To explain results from the quantum world however, the concept of probability needs to be expanded to include a so-called quasi-probability, which can be negative. This quasi-probability allows quantum concepts such as Einstein's 'spooky action at a distance' and wave-particle duality to be explained in an intuitive mathematical language. An experiment whose explanation requires negative probabilities is said to possess 'quantum negativity.' In state-of-the-art metrology however, the probes are quantum particles, which can be controlled...