# Tag Info

## Hot answers tagged scalability

23

If you take as definition "the number of transistors in a dense integrated circuit doubles about every two years", it definitely does not apply: as answered here in Do the 'fundamental circuit elements' have a correspondence in quantum technologies? there exist no transistors-as-fundamental-components (nor do exist fundamental-parallel-to-transistors) in a ...

8

tl;dr- Moore's law won't necessarily apply to the quantum computing industry. A deciding factor may be if the manufacturing processes can be iteratively improved to exponentially increase something analogous to transistor count or roughly proportional to performance. Background: Moore's law and why it worked It's important to note that Moore's law was ...

8

Ion trap quantum computers hold ions in empty space using electric not magnetic fields. That is impossible using static fields (Earnshaw's theorem) so an alternating field is used. The effect is that charged particles such as ions seek a field minimum; this type of ion trap is also called a quadrupole trap because the simplest (lowest order) field having a ...

7

You may want to check out this Schaetz et al, Reports on Progress in Physics of 2012 "Experimental quantum simulations of many-body physics with trapped ions" (alternate link in semanticscholar). In sum: yes, the arrangement of the ions is one key limitation to scalability, but no, configurations are not currently limited to a single line of atoms. On that ...

6

The first thing to understand about Moore’s law is that it is not a law in the absolute sense, mathematically provable, or even postulated (like a law of physics). Really, it was just a rule of thumb that said the number of transistors in a processor would double every x years. This can be seen in the way that the value x has changed over time. Originally, ...

6

While I’m not an experimentalist, and have not studied these systems in any great depth, my (crude) understanding is the following: In ion traps you (more or less) have to trap the ions in lines. However, this isn’t a limitation in terms of the ease of communication because what you’re probably thinking about is when a linear system has nearest neighbour ...

6

It is true that fidelity decays exponentially in the course of quantum computation. This is indeed a major limitation of NISQ computers that imposes a stringent "depth budget". In order to overcome the decay, we need gates with fidelity so close to one that the decay is negligible over the course of quantum algorithms we intend to run. As you ...

6

This reminds me of the Q20:20 engine that NQIT aimed to build over a 5-year period from January 2015 to January 2020, for which they received £38,000,000 of funding. The goal was to build a 400-qubit quantum computer made up of 20 smaller processors, each with 20 qubits. Unfortunately they failed in that aim, as most people would have predicted, because ...

5

Some near-term quantum algorithms rely on getting lucky with the measurements, and in fact these algorithms will not scale efficiently to large sizes. But most quantum algorithms don't have this problem; it is required that the amount luck needed [i.e. retries] scales only polynomially with the problem size. For example, Shor's algorithm fails if the ...

4

Plain and simple. Does Moore's law apply to quantum computing, or is it similar but with the numbers adjusted (ex. triples every 2 years). Also, if Moore's law doesn't apply, why do qubits change it? A great question, with great answers; still, I will try my hand at it. No, most quantum computers do not have qubits created in silicon; even the few that do ...

3

but aren't quantum computers much more powerful than just double-powered classical computers? Yes. A universal quantum computer with only 100 qubits (12.5 quantum bytes) can find the ground state of a matrix with $2^{200} = 10^{60}$ elements. Assuming Moore's Law could continue forever (which is not true due to physical limitations), it would take longer ...

3

This article seems to adequately explain what you are asking. It shows the growth of usable qubits in quantum computers. So the question comes up whether Moore’s Law can also be applied to quantum qubits. And early evidence suggests that indeed it may [...] The adiabatic line would be a prediction for quantum annealing machines like the D-Wave computers. ...

3

Qubits need to be able to share entanglement in order to run quantum algorithms. Qubits without entanglement are essentially classical bits. You can't just have two 50 qubit processors and treat them like a 100 qubit system, it's totally different. If you can share entanglement between the two processors, then you have a 100 qubit processor, not 2x50.

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How do you connect your two processors and with high fidelity let them communicate? As I'm sure you can imagine, it's probably fairly easy to do over classical channels, however to pass quantum information between them turns out to be very hard. Especially in the type of hardware being employed by Google and IBM. Probably the highest fidelity "flying" ...

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No, as point 4 is not satisfied. The D-Wave machines are quantum annealers and thus not universal. See this question on how to make from the D-Wave machine a universal quantum computer.

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Moore's law is not a fundamental law of the nature. It is just a heuristic mentioned by Moore to show the growing importance of computer technology. You should never take it for granted and there is nothing wrong if the actual trend doesn't follow Moore's law. Secondly, Quantum computers give speed up in only certain kinds of computations. You cannot expect ...

1

The quantum equivalent of Moore's Law is Rose's Law which states that "the number of qubits in a scalable quantum computing architecture should double every year." The prediction was made by Geordie Rose of D-Wave circa 2003. See D-Wave's Future of Hardware, this article or this amazing answer for more info. My understanding is that a quantum computer can ...

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