Quantum computing could change the world, and IonQ's quantum computing stock has fallen 26% from its October peak. Does that add up to a wide-open buying window?Quantum computing specialist IonQ (IONQ +1.57%) soared to an all-time high in mid-October, but has backed down from that peak recently. The stock closed at $59.37 per share on Oct. 23, 28$82.09 mark on Oct. 13.Is this dip an invitation to buy IonQ stock, or the start of a deeper downturn -- or something in between? Let's take a look. Why ...