Modern computers and systems seem almost miraculous in their abilities and contributions to humanity. But proponents of quantum computers say the machines we are using today will be remembered as something like a horse-drawn buggy when the next leap in computing occurs.
There are a few rudimentary prototypes, but quantum computers exist essentially only in theory for now. If they can be built, they will solve problems that today’s largest supercomputers can’t handle. First of all, scientists will use quantum computing to better understand the inner workings of molecules in order to build new materials. Another priority will be to crack existing encrypted codes and build new, even more-secure codes.
Quantum computers are based, as the name implies, on the theories of quantum physics, the laws that govern nature’s smallest component parts, such as atoms and subatomic particles. Two of the main lessons of quantum physics is that these small particles can seem to be in two places at once, and that their actions can be connected to particles very far away – even on the other side of the universe.
If humans can harness those traits in a machine, the resulting computer could make many more calculations, and much faster, than existing computers, which rely on bits of information that can only be in one state – a 1 or a 0. In quantum computers, a “qubit” will replace a bit, and will represent both 1 and 0 at the same time.
Scientific American magazine asked Jim Clarke, director of quantum hardware at Intel Labs, for an explanation of how quantum theory applies to computing.
Clarke used the metaphor of heads and tails on a coin:
“In a conventional computer processor a transistor is either up or down, heads or tails. But if I ask you whether that coin is heads or tails while it’s spinning, you might say the answer is both. That’s what a quantum computer builds on. Instead a conventional bit that’s either 0 or 1, you have a quantum bit that simultaneously represents 0 and 1, until that qubit stops spinning and comes to a resting state.
“The state space — or the ability to sample a large number of possible combinations — is exponential with a quantum computer. Taking the coin metaphor further, imagine I have two coins in my hand and I toss them in the air at the same time. While they’re both spinning they would represent four possible states. If I tossed three coins in the air, they would represent eight possible states. If I had 50 coins and tossed them all up in the air and asked you how many states that represents, the answer would be more states than is possible with the largest supercomputer in the world today. Three hundred coins—still a relatively small number—would represent more states than there are atoms in the universe.”
As you might imagine, it is difficult to build a quantum computer. In fact, some people say it will never be done. Colin Earl, a contributor to TheNextWeb.com, argues that the mechanical systems of quantum computers would be so sensitive to outside disruption, or noise, that engineers will never be able to create protections.
That’s one reason we haven’t yet seen a large and working quantum computer. The track that has advanced furthest so far requires parts of the computer to be cooled to near absolute zero (which slows down the qubits.) But there are other ways, in theory, to build quantum computers. And plenty of institutions are trying to be the first to find a solution.
China is spending an estimated $10 billion on a National Laboratory for Quantum Information Sciences. While U.S. government spending on quantum technology research is thought to be much lower, several U.S.-based companies are active in the field. The IBM Q Network is an effort to bring the first commercially viable quantum computer to market. Intel is working simultaneously on two different methods to create a workable quantum computer. Microsoft boasts that “some of the greatest minds in physics, mathematics, computer science, and engineering make up our dream team delivering cutting-edge quantum innovation.”
When a team succeeds, it will change computing and many other industries in dramatic ways, with many consigned to the museum floor, next to the horse and buggy.