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.