Silicon semiconductors have taken us a dazzling distance along the computing road. But even if they continue unabated to get faster and more powerful (and it’s growing more difficult to make that happen) there’s a limit to what classical computing can do.
The next real game-change in computing is quantum--tapping the quantum mechanical properties of materials to process information in ways that will make today’s biggest and baddest super computers look like pocket calculators. And for the first time scientists, at places like IBM, are moving beyond just theorizing about them to actually envisioning how a finished quantum computer would work. In labs across the globe, the first building blocks of the first quantum computers are slowly becoming real.
That's huge considering a working quantum computer would be the kind of thing that truly moves the ground beneath our feet. With a relatively modest quantum computer, scientists could slice through sophisticated encryption schemes, model quantum systems with unprecedented accuracy, and filter through complex, unstructured databases with unparalleled efficiency.
But first they have to build one. The idea of quantum computing was introduced in the early 1980s by physicist Richard Feynman, and the field is still very much in its infancy. But as a discipline it's turning a critical corner as the theoretical meshes with the practical. There’s more than one way to build a quantum computer, and it’s still far too early in the game to know which--if any--of these approaches will produce a working system. But between all of these varied approaches to tapping the quantum world, there’s one common thread: it’s all about the qubit.Like their classical cousins, quantum computers rely on units of information. In the classical world, that’s a bit (a byte most commonly consists of eight bits), each of which can exist in one of two states: 0 or 1. All of your data--your MP3s, your texts, your documents, your Tumblr--are nothing more than lines of bits.
The quantum analog for the bit is called a qubit. Unlike a bit, a qubit can exist as a 0, a 1, or in a state of superposition, which in quantum lingo basically means it is both a 0 and a 1 at the same time. This is where we enter the strange realm of quantum properties, where things are anything but intuitive. “You start with a sea of all possible answers in your quantum states, and you design your algorithm to peel away the wrong answers so that the right answer emerges,” says Matthias Steffen, manager of the experimental quantum computing research team at IBM Research. Rather than considering one solution to a problem at a time, you can consider multiple possible solutions simultaneously.
There are huge challenges standing between us and this mind-numbing computational payoff. Working at the quantum scale usually means working at extremely low temperatures, often bordering on absolute zero. Particles themselves are fickle. Coherence time--the amount of time the carefully cultivated quantum system is available to be read by the computer before the quantum state collapses--is measured in mere microseconds. And because there is an intrinsic margin of error in quantum computation in general, quantum computers must constantly correct themselves for errors.
Then there’s the problem of measuring quantum states, which tends to cause them to collapse. This requires a mastery of quantum correlation or entanglement--a strange quantum phenomenon that links the states of two particles together even across distances such that affecting one affects the other--so that researchers can actually measure their quantum systems without destroying them. Needless to say, absolutely none of this is easy.
That’s why researchers are starting small, pouring their brainpower and research dollars into developing a single, stable qubit--and eventually strings of tens, then hundreds, and then thousands and tens of thousands of qubits. So what might the quantum computer of the future look like? We’re not exactly sure yet, but there are a few different approaches showing a lot of promise.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.