English: The iconic textbook example of a Wigner function for a Schrödinger cat state. The bell shapes represent the “alive” and “dead” possible states for the “cat” and the oscillations between them indicate the quantum coherence between these states (i.e., the classic “both alive and dead” statement). A similar Wigner function without these interference terms would represent a state with a classical coin toss probability of being either alive or dead but not both. The presence of the interference terms indicates that this Wigner function represents a state that is in both states (“alive and dead”) at the same time (a superposition).