I agree that this may not be an easy question to answer.

But lately, I increasingly come across the fact that many news materials and research papers in the field of quantum technologies say that at the moment there is no quantum computer in the world. Instead, they argue that there are only prototypes of a quantum computer.

So what do Google, IBM, and other large companies produce? Are these really just prototypes of a quantum computer?

What about D-Wave computers (like a 2000 qubit quantum computer)?

What characteristics distinguish a quantum computer from a prototype quantum computer? And why then do some talk about a quantum computer, while others talk about a prototype of a quantum computer?

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    $\begingroup$ IMO, this is opinion question. What is prototype quantum computer? I doubt a generally accepted definition exists. $\endgroup$
    – kludg
    May 9 at 15:48
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    $\begingroup$ I would reformulate this question to focus on the last part: "What distinguishes a "quantum computer" from a "prototype quantum computer"?", to make it less opinion-based. The answer then being: there is no fundamental difference, it's just a matter of whether one considers the device as "paving the way for something else" or as a complete product in and of itself. In other words, the distinction is more a matter of marketing than of science. At the same time, the current title might also be a good target for googlers wondering about this, so I'm not strongly opposed to leaving it be $\endgroup$
    – glS
    May 9 at 17:21