
Ask HN: Is quantum computing likely in the next 20 years? - adrian_mrd
A colleague recently asked my thoughts on quantum computing. I know little about the subject but I responded that it seemed that it is still a long way off becoming viable outside of CS theorists and academic labs, based on my cursory readings over the past few yesrs.<p>What does the HN community think? Is quantum computing still a long way off? And when will we know that quantum computing has actually arrived?
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seidlitz
A number of companies like D-Wave, Rigetti, IBM, Intel, and Google already
have processors working on quantum principals
([https://en.wikipedia.org/wiki/List_of_quantum_processors](https://en.wikipedia.org/wiki/List_of_quantum_processors)).
There are also examples of quantum algorithms that are demonstrated to work.
The main question is weather quantum computers will be able to do anything
that classical computers can't do (or do it cheaper/faster). There is still a
number of obstacles that need to be overcome to make quantum computing
reality—a so called DiVincenzo's criteria:

\- physical scalability of qubits; \- qubits initialization \- dealing with
quaantum decoherence \- universal gate set; \- reliable reading of qubit
states

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sgillen
Quantum computers definitely exist, as to when they will be useful is anyone's
guess.

Furthermore my money is on a nation state (probably US or China) being the
first to get a useful quantum computer. I expect that will be as classified as
possible so we may not know for many years once they have one.

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buboard
It is and it isn't

