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Here is a quick list of notable differences between analog and quantum computers: Analog computers can't pass Bell tests. The state space of an analog computer with N sliders is N dimensional. The state space of a quantum computer with N qubits is $2^N$ dimensional. Error correct an analog computer and what you've got is a digital computer (i.e. not ...


10

You have two different questions here: 1) Can quantum computing be profitable without quantum hardware? In the comments people have said this is an opinion based question, but the truth is that there's already people (and companies!) making profits off of quantum computing. In 2016 Doug Finke made a website with his own money, which kept track of the ...


7

A logical qubit is a very fluid concept. You could use physical qubits as logical qubits. Or, you can encode multiple physical qubits as a single logical qubit. The more physical qubits you use, the better the resistance to noise. So, I would suggest that you question isn't exactly the right one to ask, and a better question is whether something useful can ...


7

What work has been done on the mapping of quantum phenomena to analog computing, and learning from that analogy? A starting place (with a lot of good references) to learn about analog quantum computing (also known as "quantum analogue computing" and "continuous variable quantum computing") is here. Note that analog classical computing is not as powerful as ...


6

There are a lot of interesting applications that use similar technology. A lot of labs that work towards quantum computing also publish papers with these applications. Here are some: All-optical computation. Personally, I think this has more potential than quantum computing, as it has already been shown to be useful for quickly processing neural networks ...


6

According to this UK-oriented report by Gooch and Housego dated May 8, 2018, quantum computing is only one of several main key applications expected to have a market impact: Clock technology/timing (e.g. bridging between the optical frequencies typical of atomic clocks and electrical/microwave frequencies typical of timing signals within ...


5

When you ask, I am wondering whether these elements would be somehow imitated by the means of quantum technologies there are different levels on which you can interpret this question. You might mean to ask whether people will realise quantum capacitors, inductors, or resistors, or you might mean to ask whether people will realise components which, in ...


4

Perform and checking basic quantum-mechanic experiments Before the IBM and alibaba quantum cloud computers, you would need an expensive lab to do simple CHSH or GHZ experiments. Of course the qubits in the IBM computer are not loophole free but many institutes and also collegeschools could not have better experiment facilities purchased within their physics ...


4

Microsoft is the only company that is trying to build a topological quantum computer. You mention that topological qubits handle noise far better than other systems, but they are also theoretical. That's the reason Microsoft is applying a topological approach. It's high-risk, high-reward. If Microsoft manages to realize a topological qubit, scaling up a ...


4

The only two quasi-particle quanta for which I know there to be active research in quantum computing are phonons and anyons. Phonons: That state-of-the-art is given my answer here: Phononic Quantum Computing Anyons: Synthesizing the first anyonic qubit is still an outstanding goal, but major milestones have been discussed very recently. This paper was the ...


3

Are quantum computers just a variant on Analog computers of the 50's & 60's that many have never seen nor used? No, they are not. The digital vs analog factor is not the point here, the difference between quantum and classical devices lies at a more fundamental level. A quantum device cannot, in general, be simulated efficiently by a classical device, ...


3

Thinking about the theoretical capabilities of quantum computers has led to important insights on the theory of classical computers. One example is the proof that the (classical) complexity class PP is closed under intersection. While there was already a purely classical proof due to Beigel, Reingold, and Spielman, there exists a simpler proof that uses ...


3

In complement to the other answer from @user1271772: 1) Can quantum computing be profitable without quantum hardware? I can add another two elements. First companies that can sell/develop anti-quantum security protocols because as you may know, RSA is threatened by quantum computers (at least in theory but it can be enough to transition to new protocols)...


2

At this early stage of quantum technology development, a useful starting point to understand the "expectation of profitability" is to look at the private markets (angel investing, venture capital, private equity, etc) in addition to public companies. Today there are 76 companies active in quantum computing, those were involved in 178 deals where 260 ...


2

Executing a NISQ-device in a manner that asymptotically outperforms a classical computer invalidates the Extended Church-Turing Thesis (ECT). Voluminous tomes written about the (non-extended) Church-Turing Thesis, with implications for branches of philosophy such as the philosophy of mind. The fact that the ECT was not only falsifiable but also is likely ...


2

I am wondering whether these elements would be somehow imitated by the means of quantum technologies and what would be the requirements to achieve them I don't think we would want to achieve quantum equivalents of resistors, capacitors, inductors etc (at least as of now). There are two parts to any circuit: 1) Logical implementation 2) Physical ...


2

These elements do not necessarily have a correspondence in quantum computers, just as they do not necessarily occur in classical computers (an electronic computer might use some of them, but a mechanical or photonic computer does not necessarily have any equivalent of them). What has an equivalence are the fundamental gates that form a classical computer. ...


2

Have we fallen into the same 'everything digital' bandwagon trap that keeps recurring? What I have noticed is more the 'everything binary' bandwagon trap; which reminds me of the Grandma's cooking secret: Once upon a time, a mother was teaching her daughter the family recipe for making a whole baked ham. It was the very best ham anybody had ever had so ...


1

I'm not sure if you count adiabatic quantum computing as fringe, but there was a paper using 4 NMR qubits to implement a adiabatic analogue to HHL which allowed them to invert an 8x8 operator with 98.4% fidelity which got put on arXiv a couple weeks ago. I thought that was pretty neat.


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