84

I'll be trying to approach this from a neutral point of view. Your question is sort of "opinion-based", but yet, there are a few important points to be made. Theoretically, there's no convincing argument (yet) as to why quantum computers aren't practically realizable. But, do check out: How Quantum Computers Fail: Quantum Codes, Correlations in Physical ...


33

Classical computing has been around longer than quantum computing. The early days of classical computing is similar to what we are experiencing now with quantum computing. The Z3 (First Turing complete electronic device) built in the 1940s was the size of a room and less powerful than your phone. This speaks to the phenomenal progress we have experienced in ...


16

Early classical computers were built with existing technology. For example, vacuum tubes were invented around four decades before they were used to make Colossus. For quantum computers, we need to invent the technology before we make the computer. And the technology is so beyond what had previous existed, that just this step has taken a few decades. Now we ...


15

TL,DR: Engineering and physics arguments have already been made. I add a historical perspective: I argue that the field of quantum computation is really only a bit more than two decades old and that it took us more than three decades to build something like the MU5. Since you mention the timeline, let's have a closer look: The beginnings First of all, the ...


11

When you ask whether it is pie in the sky, that rather depends on what promises you think quantum technologies are trying to fulfil. And that depends on who the people are making those promises. Consider why you are even aware of quantum computation, given that it hasn't yet managed to produce any devices (or to be more fair, not very many devices) which ...


11

To answer part of the question, "will I ever buy a quantum computer", etc. I think there is a fundamental misunderstanding. Quantum computing isn't just classical computing but faster. A quantum computer solves certain kinds of problems in a short time that would take a classical super computer a thousand years. This isn't an exaggeration. But regular kinds ...


10

TL;DR: I've been working on the theory of quantum computers for about 15 years. I've seen nothing convincing to say that they won't work. Of course, the only real proof that they can work is to make one. It's happening now. However, what a quantum computer will do and why we want it does not match up with the public perception. Is quantum computing just ...


8

See the timeline on Wikipedia, and ask yourself where's the parallel adder? It seems to me that your answer lies in your question. Looking at the timeline on Wikipedia shows very slow progress from 1959 until about 2009. It was mainly theoretical work until we went from zero to one. In the only 9 years since then, the pace of progress has been ...


8

Why would you expect two different technologies to advance at the same rate? Simply put, quantum computers can be immensely more powerful but are immensely harder to build than classical computers. The theory of their operation is more complicated and based on recent physics, there are greater theoretical pitfalls and obstacles that inhibit their scaling up ...


7

I won't be giving any precise statements about which problems can be solved more efficiently using quantum algorithms (compared to existing classical algorithms) but rather some examples: Discrete Fourier transform (DFT) is used in pretty much all modern day music systems, for example in iPods. That algorithm single-handedly changed the world of digital ...


7

Like all good questions, the point is what you mean. As the CTO of a startup developing a quantum computer, I have to emphatically disagree with the proposition that quantum computing is just pie in the sky. But then you assert "You won't be buying one in PC World any time soon." This I not only agree with but would suggest that in the foreseeable future, ...


6

The difficulty with explaining quantum computing is that quantum objects and processes have no direct classical analogue; they're an entirely new ontological category. For example, you might have learned in high school physics that light "is both a particle and a wave" in an attempt to relate it to two classical objects you can intuitively understand. In ...


5

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 ...


5

There are many technical challenges to developing a universal quantum computer consisting of with many qubits, as pointed out in the other answers. See also this review article. However, there may be workaround ways to get certain nontrivial quantum computing results before we get to the first truly universal quantum computer. Note that classical computing ...


5

Not always. Some problems are non-deterministic (their solution). Apart from that, some problems are, as you say, so sensitive to changes in initial conditions, that most solutions are too localized. But there are cases where quantum computers can provide insightful results, that might shed light on different approaches to solutions. Another point to ...


4

No. Chaos (as described in chaotic systems) is deterministic, and the evolution of such a system can be calculated using classical deterministic equations. The problem is the strong divergence of the different trajectories that even small differences in initial values can lead to large differences in the final values. Quantum computing does not help in ...


3

A couple years ago it was shown in Quantum algorithms and the finite element method by Montanaro and Pallister that the HHL algorithm could be applied to the Finite Element Method (FEM) which is a "technique for efficiently finding numerical approximations to the solutions of boundary value problems (BVPs) for partial differential equations, based on ...


3

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 ...


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)...


3

There are lots of separate questions in there: politics, physics, etc. and I won't pretend to answer all of it, but let me try to get towards what I think is the core of the matter. How do I explain to the interested non-specialist what I do (the general field)? My explanation actually varies a lot depending on who I'm talking to, and depends a lot on ...


3

I was not able to find references specifically in quantum biology. I found however a review called Quantum Assisted biomolecular modeling. You may find it interesting but this is from 2010. The field has evolved since but I guess the ideas remain similar. The authors focus more on the idea of the ability of a quantum computer to try every classical paths ...


2

Quantum simulation can be used to test models that could describe certain biological process. For example, a 2018 paper by Potočnik et al. examined light harvesting models using superconducting quantum circuits (see figure below). Currently, it's an open question whether quantum mechanics plays an important functional role in biological processes. Some ...


2

When explaining quantum computers, we must deal with the fact that most people don't know the fundamentals of classical computers. Since the difference lies at this fundamental level, that can present a problem. Nevertheless, many people know that information technology comes in analogue form as well as digital. That already gives them an intuition that ...


1

Speculatively expanding on previous answer Quantum computers tend to outperform classical computers in determining global properties of functions. Further, the properties tend to be some measure of global symmetry. Based on the global symmetry, the probability amplitudes can constructively (and destructively) interfere, in ways that a classical computer ...


1

As an initial matter, let's ask "what is the classical computational complexity of solving 'mate-in-$n$' type games?" For example, is it even in $\mathcal{NP}$ to know, given a certain chess position, that white can mate in $10$ or fewer moves? It's been known for a while that we can consider such questions as a "quantified boolean formula" (QBF) question. ...


1

In this survey article they discuss Grover's algorithm. In my opinion, the most important part: Grover’s speed-up from $N$ to $\sqrt{N}$ is not as devastating as Shor’s speed-up. Furthermore, each of Grover’s $\sqrt{N}$ quantum evaluations must wait for the previous evaluation to finish. To quantify this issue, define T as the number of serial ...


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