OK, I am shocked by quantum theory. Who wouldnıt be, it just doesnıt fit my common-sense view of how the world should work. Not long ago, I read a fictional novel by Michael Crichton called Timeline. I highly recommend it. It has some great stuff about medieval times. And it employs quantum theory to allow time travel. Just one of the many things you can do when you realize the world doesnıt actually make sense. Now Iım not here to discuss quantum time travel, but I will discuss another quantum idea being explored in computing.

Quantum Basics

Letıs just review the basics for a moment. The first time I heard of the double-slit experiment, I went into the bathroom with a flashlight to find out for myself. I can confirm that light appeared to be a wave according to my analysis. You could clearly see the multiple lines of interference on the wall (this link will save you a trip to the john). But then it gets confusing. Because if you start throwing electrons (little packets of stuff) at a wall through two slits, you will get this same pattern. But if you think about it, it doesnıt make sense. Kind of like shooting curving bullets. Worse yet, if you try to measure what electrons are going where, you get two lines, exactly what you would normally expect.

Quantum theory was created to explain this odd phenomenon. In a nutshell, quantum theory says that when you are not looking, the electrons or other quantum stuff are in both places at once. Then when you measure them, they are either in one place or the other. From this springs the duality of light, uncertainty, and dead cats in boxes.

Two places at once!? Now that could be handy when you are trying to get some work done at the office, and still complete all the chores at home. But other than that, what use could it be?

When a Bit Is a Little More Than 1 or 0

Can you imagine a computer that used switches that were more than just 1 or 0? It would have bits that were in more than one place or state at a time. In fact, these would be called qubits, short for quantum bits. When you get a bunch of these qubits together, they can do some amazing things. They really can be doing two things at once. Think about how that would multiply. Two qubits could thus do four things at once, three qubits could do eight, and so on. Pretty soon you have one powerful computer (no, it's not a G5).

Killer Apps

Now we have learned from experience that no computer is worth anything without a killer app. So what is the killer app for a quantum computer? I will list a few.

A guy by the name of Ronald de Wolf proposed a quantum fingerprinting scheme where exponentially less quantum information represents a cornucopia of data such that only 40 quantum bits ("qubits") would be needed to fingerprint a novel of 1,000 pages. That could improve database organization immensely. And a variation on this technique could do wonders for compression methods.

How about break all the security codes in the world? An RSG (really smart guy) by the name of Peter Shor came up with a quantum algorithm that could factor all the security codes in, oh let's say a lazy afternoon. That got the Department of Defense interested. I donıt pretend to understand the methodology. I just think that my own personal hypothesis touting the connection between hair and brains is on its way to being a proven theory.

So what do you do to deal the code breakers? Well, you invent quantum cryptography. This basically uses Heisenberg's uncertainty principle to create coded information that is irrevocably changed when the bad guys try to read it.

Sick of search engines? Another RSG by the name of Lov Grover developed a series of instructions for a quantum computer to perform exhaustive searches. For example, to dig out an item from a list of 10,000 items, a regular plain olı computer would require some 5,000 steps. Because it uses more that just 1 and 0, a quantum computer using Groverıs algorithm would need only 100 steps.

How about teleportation? It is also believed that one of the ramifications of quantum theory is the ability to transfer data instantaneously and, yes, even photons over a distance. This has to do with quantum entanglement, something Einstein referred to as "spooky actions at a distance."

It looks like anything is possible when anything is possible!

The Skinny

"Where a calculator on the Eniac is equipped with 18,000 vacuum tubes and weighs 30 tons, computers in the future may have only 1000 tubes and weigh only 1½ tons."
– Popular Mechanics, March, 1949

So where is all this going? Nowhere fast? Or somewhere amazing? One of the problems is the fact that the slightest disturbance topples the whole apple cart. Something that has most researchers scratching their collective heads. But here is one interesting approach. Two ESG (extremely smart guys), Neil Gershenfeld and Isaac L. Chuang, have figured out a way to make the disturbance problem a moot point. They use nuclear magnetic resonance (NMR) to adjust quantum states of carbon atoms in a molecule called alanine. These molecules are suspended in liquid and used as qubits. Since they are working on a much larger scale than most researchers, and the system inherently has multiple copies running at any given time, they have had success in making it work. They have even built a computer that can add one and one and give the result. They also ran the Grover search algorithm mentioned above. To quote Dr. Chuang, "It's a little like having a million monkeys typing in Microsoft Word." No stopping now, Gershenfeld and Chuang are planning a 10-qubit computer using more complex molecules (and I am not making this up!) such as the caffeine in your coffee.

Will We See Results?

You can definitely apply for a quantum job. That means someone is pouring money into it. And my experience is that enough money will get results (not necessarily fast or efficiently, mind you). I think there is definitely a chance we will see quantum computers in our lifetime. Who knows, a few years from now you may be desperately trying to enter that last bit of info into your cup of coffee before you leave for the day.

I think it is kind of ironic that it wonıt be decaf.

"Nobody understands quantum theory."
– Richard Feynman, 1967