But there’s a major catch: qubits are easily disturbed by photons of light or heat or just about anything else in the natural environment. As soon as one tries to interact with a qubit, its value changes and it can even lose its crucial superposition characteristic.
In February, Mika Sillanpää and his colleagues at Aalto University reported that they had found a way to interact with a qubit without messing with its superposition.
They built a tiny device that simulates the quantum state of a single atom. Sillanpää calls his device a kind of "artificial atom" (above). It consisted of a tiny piece of aluminum attached to a bit of sapphire. The scientists connected this component to a small piece of material capable of vibrating, called a resonator.
They put both components into a small cavity and cooled them to just above absolute zero. That turned the aluminum into a superconductor. Superconductors are known for conducting electricity with no resistance and can also behave as single atoms, entering a quantum state.
When the aluminum entered a quantum state, its energy made the resonator vibrate in a particular way. The vibration stored the quantum state information, or qubit. At the same time, it transferred energy into the cavity, which emitted a microwave photon that could be detected. It was the first time anyone had turned a bit of quantum information into a mechanical motion linking qubits to the outside world. It's like an electron inside a conventional computer being converted into a pixel of text on a screen.
Silanpää told Discovery News that theoretically, by reversing the steps and firing a microwave photon at the component, the scientists would be able to change the quantum state of the artificial atom. A successful experiment demonstrating this -- next on his list -- would be similar to having a keyboard that entered new information into a computer.
This kind of link, or interface, between the quirky energy states of quantum particles and the macro world of tangible computers is necessary if we're ever going to harness quantum power.
NTT scientist Bill Munro said since the device allowed for reading and writing qubits, it was a big step toward a useful computing device.