The downside of investing in quantum computing pure plays is that there is no backup plan. If another competitor and its technology surpass Rigetti's, the stock becomes obsolete, and every share is worthless, ultimately sending the stock to $0. That's a grim outlook, but it's entirely within the realm of possibility.

Wall Street got the message, with Rigetti stock jumping 30% Wednesday, trading at $16.56. The breakthrough system is built on four 9-qubit “chiplets,” using Rigetti’s tailor-made modular chip architecture. It’s the company’s latest effort in developing larger and more robust quantum machines.