Saturday, July 14, 2018

Quantum Computing For Computer Scientists


Quantum computing is coming, so a lot of people are trying to articulate why we want it and how it works. Most of the explanations are either hardcore physics talking about spin and entanglement, or very breezy and handwaving which can be useful to get a little understanding but isn’t useful for applying the technology. Microsoft Research has a video that attempts to hit that spot in the middle — practical information for people who currently work with traditional computers. You can see the video below.

The video starts with basics you’d get from most videos talking about vector representation and operations. You have to get through about 17 minutes of that sort of thing until you get into qubits. If you glaze over on math, listen to the “index array” explanations [Andrew] gives after the math and you’ll be happier.

Billing the Deutsch Oracle as an example of why quantum computing is superior makes us nervous. The premise is you can identify a black box in one operation as opposed to two in a classical computer. The problem is that to do that, you need to modify the black box to take an extra bit. Well, if I can modify the black box to take an extra bit (in a different way) with a classical computer, I can identify the function in one operation, also. However, it is a good explanation of a fundamental concept — it just doesn’t bear scrutiny that it demonstrates the advantage of quantum.

It might be better, in our opinion, to show how it mirrors parallelism in classical computing. For example, if I can modify my black box to do the same operation on two bits in parallel, I get the same result. The quantum modification — granted — is simpler, but it still required you to add an extra bit and modify the black box.

The video closes with some live demos using the Microsoft tools. If you watch this video and want to do some hands-on in your browser — or even a real machine — you might enjoy our tutorial series. If you are trying to just explain or understand quantum computing at a higher level, the IBM videos are a lot more breezy.
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