Actually, it is not a matter of silicon rather it is a matter of language. Binary is the system of language that computers use and, therefore, are limited to decisions related to 1 and 0, or on and off. On the other hand, quantum mechanics allows us to develop a computer that can go way farther than yes and no, though silicon is still useful as a resources if somehow there was a language that could imitate the properties of languages developed using quantum mechanics.