A  quantum computer is the pot that, if watched, really won't boil.  Charles Bennett described quantum information as being “like the information of a dream - we can’t show it to others, and when we try to describe it we change the memory of it.” When one turns to a quantum computer for an “answer”, that answer, from having been held in that strange entangled way, among many particles, need to surface in just one, ordinary, unentangled place.  That transition from entanglement to non-entanglement is sometimes termed “collapse”. Once the system has collapsed, the information it holds is no longer a dream or a secret or a strange car at once alive and dead the answer is just an ordinary thing we can read off a screen. 

Rivka Galchen, Dream Machine