In May this year, IBM announced it was making such a device available for anyone to use over the internet. Its computer has five quantum bits, or qubits, so can only handle relatively small problems – but it’s programmable just like a regular PC. Researchers at Google have developed a similar device, although have not made it accessible to the public.
Both of these computers use superconducting qubits built using techniques from the conventional computer chip industry. Now, a team at the University of Maryland has succeeded with its own quite different approach to making a programmable five-qubit computer.
Their qubits are made from ytterbium ions held in place by magnetic fields and lasers, a technology with its origins in atomic clocks. “Ions are nature’s quantum units,” says team member Shantanu Debnath. “If you have a bunch of them in a processor, all of them are identical, and that is a significant advantage.”
Trapped-ion qubits have another edge over the superconducting variety in being able to communicate with each other at a distance, thanks to the weird property of quantum entanglement. This allows the computer to process data more easily. “Any ion can interact within any other,” says Debnath. “Quantum entanglement is at the heart of parallel processing and speed-up.”