40 First quantum processor built

1. The breakthrough

Write down the date of January 12th, 2006, because it’s going to be in the history books; the history of computing, cryptography and physics, that is. It’s the day when Christopher Monroe’s team at the University of Michigan, USA, has announced the creation of an actual quantum processor.

The processor was built using everyday semiconductor technology, akin to that found in every computer we use today, and includes an artizanal ion trap, which in turn provides for exactly one quantum bit (qubit).

The news has already been picked up by many places, such as Slashdot, Wired or Top Tech News. I recommend you take a moment and read those sources, perhaps one of them will help you understand this whole thing better.

Why is this big news? You would know if you’d have read The Code Book, like I did. :) It’s one of the first actual applications of quantum computing in real-life.

In 1997, in their “Brief history of quantum computing”, Simon Bone and Matias Castro were estimating that it will probably take 10 years for an actual quantum computer to be created. Turns out they were right. It’s 2006 and by next year we will probably see such a beast appear.

2. What does it mean?

Quantum computing is an attempt to bring the theory of quantum physics into the realm of computers. It’s next to impossible to make an introduction to quantum physics in just a few words, but I’ll try to at least give you an idea of what this is big news.

You know how regular computers use bits, right? The bit is the building block of all information, the way it’s stored into all computers and electronical devices we use today. We define a bit as a logical unit which can have either a value of 1 (one) or 0 (zero). By stringing together these bits we can express numbers in base 2 (such as 10110110), which we can then use to express whatever we need: numbers in other bases, letters and so on, building towards more complex information such as a picture on your desktop or a Tetris game.

Instead of bits, quantum computing uses qubits. A qubit differs from a bit in that instead of being either 1 or 0 at any point in time, it is both at the same time. Yes, I know. It blows the mind.

3. But what does it MEAN?!…

If you’re new to this whole quantum thing, you can’t even begin to imagine the kind of stuff this makes possible. Imagine that instead of having to spend a lot of time exploring all the alternate solutions of a problem, expressed in bits, sequentially, we can express them in qubits and explore them all simultaneously, no matter how many they are. OK, so it will probably matter how many, but for every other solution you can encode and process at the same time, the computing time shortens with another order of magnitude.

This kind of computing is so strange that to date there are only a handful of quantum algorithms imagined for it. Among them is one that can search in an unsorted database, as well as one that factors numbers.

For as long as quantum computers were a dream, these algorithms were just theoretical beauties. But the day we get actual quantum computers, even only these two algorithms will spell revolution. Databases are used almost everywhere in the world of computing, so you can imagine how useful the search algorithm will be. As for the factoring one, let’s just say that the most powerful encryption techniques of today are based on the idea that you cannot factor very large numbers in any reasonable amount of time. Well, how does one second sound?

4. It’s not all roses

Don’t go for the champagne bottle, though. First of all, we don’t have quantum computers, we only have an experimental quantum processor, in a laboratory, with one tiny qubit. It’s going to be a while until you can have any kind of device which uses quantum computing on your desk. It can even be speculated that at first there won’t be computers at all, just coprocessors incorporated in the regular machines, which will be used for specific tasks (such as search or encryption).

Second, it’s not all good news. For example, consider that this will render all the old encryption methods useless. And that spells a lot of trouble for everyone’s privacy:

• We don’t yet have a countermeasure, which would be quantum encryption. Oh, we have theories, but they are just that. Indeed, if you can solve any given problem in exactly one second, how can you expect to ever encrypt anything again?
• Ordinary people won’t be able to afford quantum decryption, at least for a while. We can even go as far as to imagine that certain governments will take care that quantum computing is equated to a powerful weapon (like the US already does with the best known encryption techniques) and forbid foreigners or even their own citizens from legally getting devices using it. This means that governments will be able to decrypt all communications, while the regular people can’t hide anything anymore.
• If a University came out publicly with a working quantum processor today, you can most likely bet that an obscure government lab somewhere has had one for a while. How long? Who knows…

See you on the other side.

Update (Sep 14, 2007): Two independent research teams make quantum computers and start attacking number factorization