If you’ve ever wondered how fast a quantum computer really is, scientists at the University of Science and Technology of China can tell you: fast enough to complete in three minutes a calculation that would take today’s fourth-best supercomputer an estimated 200 billion years to solve.
Conventional computers process information, moving as an electrical current, sequentially as a one or a zero through a silicon chip. In contrast, quantum computers use qubits – usually a piece of a phosphorus atom – to take advantage of a quirk of quantum physics: a qubit can be a one and a zero at the same time, enabling a quantum computer to sort, compare, and process data orders of magnitude faster than regular computers.
Quantum computers usually rely on electrical superconductors, which have to be cooled to near absolute zero. The Chinese team eliminated superconductors and instead adopted a technique called “boson sampling” in their device that uses photons – particles of light – instead of an electric current to transmit data.
Photons were sent into the new computer one by one, then beam splitters divided each one and bounced it through a series of mirrors. Boson sampling calculates the possible output of that series of bounces, a chore conventional computers couldn’t keep pace with.
The Chinese machine, with its 300 beam splitters, 75 mirrors, and 25 custom-tailored crystals, calculated the distribution sample in about five minutes. In contrast, the researchers calculated that Sunway TaihuLight, now the world’s fourth most powerful supercomputer, would have needed more than two billion years to arrive at the answer.
If any other computer would take two billion years to make the calculation, how did the Chinese engineers know that their machine got the right answer?
They say they tested minor portions of the larger calculation on Sunway TaihuLight and found the answers consistent with those from their quantum machine. Also, they determined if the new machine-made any mistakes, it would have malfunctioned in minor but detectable ways, which it didn’t.
TRENDPOST: No one knows when quantum computers will be of practical use; so far, the machines have been testing various architectures and demonstrating possibilities. When they become practical, likely, they will first be used to make calculations involving vast uncertainties, such as predicting next Monday’s Dow Jones’ close.
The world is not yet capable of imagining what will result if, or when, artificial intelligence and quantum computing are joined together.
