Sean Carroll

Well, all I want to say about it is John Preskill, who's a good friend of mine and a great physicist, former podcast guest here, he was a pioneer in quantum error correction.

If you have a quantum computer and you have these qubits, they're entangled.

What do you do if one of the qubits gets messed up?

It turns out to be much, much harder than for a classical computer because of the entanglement between different qubits.

And when I first heard the term, I was like, that sounds like the most boring thing in the world, quantum error correction.

But I was super wrong.

It turns out to be absolutely central, not just to building quantum computers, but to many ideas in theoretical physics.

So hopefully I've learned my lesson.

Yeah.

Well, if you send a classical message, so let's say you send a single bit, right?

A zero or a one.

There's a very simple strategy, which is just to send three copies of it, right?

And if there's some noise and there's some chance that one of the bits gets flipped, but it's a small chance,

Then at the end, you get your three copies, and if one of them is wrong, you just discard it.

You take the majority rules, and that works very, very well classically.

But quantum mechanically, if you mess up one of those bits, it's entangled with the others, and it ruins everything.

So you need to have a – you need to invent a new kind of quantum redundancy, which I'm not going to explain right now.

But it turns out that that idea of quantum redundancy might be crucial to understanding the origin of space and time.

So it's the universe kind of doing maintenance on itself.

Well, the first thing you need to do is some theory.