What is quantum computing?

How does quantum computing stack up against traditional computing? Very well, according to futurist Isaac Arthur.

Quantum computing: Defined

Dan Patterson, a Senior Producer for CBS News and CNET, interviewed futurist Isaac Arthur about quantum computing. The following is an edited transcript of the interview.

Isaac Arthur: Technically, quantum computing is any type of computing that relies on quantum mechanics to actually produce the data. In fact, there are some who suggest that perhaps the human brain might actually have some quantum computing capacity. But what we usually mean is the use of the qubit--which is like a normal bit, which can be either a zero or one--but a qubit, it's able to be a zero and a one simultaneously, same as like [Erwin] Schrödinger's experiment where we have the cat both alive and dead. Our goal with these is to create a whole bunch of these qubits, or a whole bunch of these cat boxes, and entangle them so that we can actually do a very large amount of computing with them.

This potentially allows you to have, instead of one sentence on a piece of paper--as it were--composed of various bits of data--to have all possible sentences up there simultaneously, with the hardest part, of course, being that we only want to pick the one that we want to see. That's where quantum computing comes in very handy is, it runs every single option simultaneously, and then we just have to figure out a way to actually see the one we want.

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The biggest difference in terms of computational method is that with a quantum computer, we can do certain things that a normal classic computer can't do. Almost any problem that you can set up on a classic computer has a version of it where it's going to kind of snowball exponentially, so it has a very large number of possibilities. 

The difference between trying to figure out what the odds of two coins flipping are versus the odds of every single combination of a hand of cards in poker--and with classic computing, every time you add another element that's connected to the others, you're increasing that amount quite a lot. And you can eventually start getting problems that are so complicated that even if you turn the entire planet into a computer, and even if it had a billion years to calculate, it still couldn't solve those. Of course, we use that for encryption models.

A quantum computer has the option to, basically, solve all of it simultaneously, so it's also very handy for things like search algorithms because with a normal computer, you could tell it, 'I want you to find a single sentence in this library or database,' and it's going to go through looking at each individual one. With a quantum computer, I could tell it to search a random page in that library, seal it inside that box that creates that superposition, and it will have searched any number of random pages, all of those random pages, and it only has to spend the time to search one page. Ultimately, of course, to get us to make sure that it only lets us know when it found the page that had the right answer on it.

Watch more interviews with Dan Patterson and Isaac Arthur

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