Small zap from a laser, quantum leap for computer-kind

Small zap from a laser, quantum leap for computer-kind

For the first time, scientists have figured out how to reprogram a quantum computer - shoot lasers at it.

Quantum computers, which are exponentially more powerful than the binary kind we're used to, have so far been limited to performing single calculations. They're fast, but essentially useless if that single type of calculation isn't what you need.

"You can get it to do one type of algorithm, then if you want to do a different one you have to build a whole new computer," nanotechnology scientist Michelle Dickinson told Paul Henry on Monday.

But now researchers at the University of Maryland have built a reprogrammable quantum computer. It's made of only five atoms, held together by a magnetic field. The physics behind how it works are incredibly complex, but Ms Dickinson makes it sound simple.

"They shoot lasers at stuff to reprogram it, and they use magnets to keep the [atoms] in, and it's tiny and now it can solve different things so you don't have to build a new computer."

Ordinary binary computers are starting to push up against the limits of conventional physics - you can only cram so much data and computation into smaller and smaller places.

Bits of information can only be one or zero, but in a quantum computer, bits - known as qubits - can be both or anything in between.

"If you were a quantum particle you could be here and somewhere else, and not there, and you could be dead or alive. So it's a bit confusing," says Ms Dickinson.

Because of this, quantum computers can also perform many tasks simultaneously - normal processors can only do one thing at a time.

"If you imagine you go to the library, you as a binary computer… could read one book at a time, whereas a quantum computer could go to the library and read them all at the same time. It can do a lot more calculations."

The Maryland scientists believe their five-atom computer could easily be scaled up to run consumer devices. It's already shown it can solve three problems at the same time.

"For any computer to be useful, the user should not be required to know what's inside," says research leader Christopher Monroe. 

"Very few people care what their iPhone is actually doing at the physical level. Our experiment brings high-quality quantum bits up to a higher level of functionality by allowing them to be programmed and reconfigured in software."

The research was published in journal Nature.