Could this quantum computer be the real deal?

[n2doc]

By Chris Lee | Published about 17 hours ago

I have been writing about quantum computing for a while now. If you look at my recent writing, though, you won't find much about quantum computing. Why? Well, it all felt a little repetitive. The publications were still coming, but each new one seemed very much like the previous one. I'm not being cynical here; sometimes you just burn out on a subject.

In that light, it takes something special to attract my attention. It turns out that making something that looks and feels like a complete quantum computer—albeit on the smallest of scales—will definitely attract my attention. What we have here, ladies and gentleman, is nothing more or less than the first quantum microprocessor.

Quantum computing has turned out to be a challenge because it relies on encoding information in quantum bits (qubits) that have two fundamental properties. The first is coherence, which allows qubit states to naturally change in a syncronized manner. The second is quantum entanglement, which correlates the states of different qubits with one another. When we perform operations and measurements on a qubit that is entangled with another qubit, we automatically learn about and modify the state of its partner. This provides a sort of quasi-parallelism that allows a quantum system to perform some calculations faster than a classical computer.

But a computer is more than its bits. You need a register to hold qubits and perform operations on them. You need a memory, so that you can store qubits between operations. And you need to be able to initialize and readout the qubit so that you can begin and end a calculation. Now, there are groups of researchers who have done all of these separately. And, using trapped ions, some groups can even claim to have done the whole lot together. But I don't think anyone seriously thinks that tables full of optics, lasers, and vacuum systems is the way to quantum computing nirvana.

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http://arstechnica.com/science/news/2011/10/could-this-quantum-computer-be-the-real-deal.ars