This is a brief review of the experimental and theoretical quantum computing. The hopes for eventually building a useful quantum computer rely entirely on the so-called "threshold theorem". In turn, this theorem is based on a number of assumptions, treated as axioms, i.e. as being satisfied exactly. Since in reality this is not possible, the prospects of scalable quantum computing will remain uncertain until the required precision, with which these assumptions should be approached, is established. Some related sociological aspects are also discussed.I do think that QC is a failed research program.

QC starts with the hypothesis that it is impossible to efficiently simulate a quantum system with a classical (Turing) computer. I suspect that is correct. But the leap to scalable QC seems extremely doubtful to me.

Not a rhetoric but a simple question: What minimum power must a quantum computer have, before it could be said to be a well-scaled one? How many qubits? Where do the quantum computing researchers draw the line, if they do?

ReplyDeleteAt least as of today it cannot be a very precise line, I suppose, but it doesn't have to be so anyway. A rough indication would do. But unless one has some indication of such a datum, one couldn't begin to think very meaningfully about this issue.

--Ajit

[E&OE]