Google said on Wednesday it achieved a breakthrough in computing research by using a quantum computer to solve in minutes a complex problem that would take today's most powerful supercomputer thousands of years to crack.
Google researchers expect that quantum computers within a few years will fuel advancements in fields such as artificial intelligence, materials science and chemistry. The company is racing rivals including IBM Corp and Microsoft Corp to be the first to commercialise the technology and sell it through cloud computing units.
"We’re hoping that when people start using this and looking at performance stability and cloud interface, they’ll get really excited about what we have to offer at Google," John Martinis, the company's chief scientist for quantum hardware told reporters.
Official confirmation of the breakthrough came in a paper published in science journal Nature, after weeks of controversy following the leak of a draft, over whether Google's claim of "quantum supremacy" was valid.
For decades, computer scientists have sought to harness quantum physics, laws governing the behaviour of sub-atomic particles that can simultaneously exist in different states - in contrast to the everyday world that people perceive.
So, whereas traditional computing relies on bits, or ones and zeros, quantum computing uses quantum bits, or qubits, that can be both one and zero at the same time.
This property, called superposition, multiplies exponentially as qubits become entangled with each other. The more qubits that can be strung together, the vastly more powerful a quantum computer becomes.
But there's a catch: Quantum researchers need to cool the qubits to close to absolute zero to limit vibration - or "noise" - that causes errors to creep into their calculations. It's in this extremely challenging task that Google, aided by liquid helium for cooling, has made significant progress.
CEO Sundar Pichai compared the achievement to building the first rocket to leave the Earth's atmosphere and touch the edge of space, an advance that brought interplanetary travel into the realm of the possible.
"For those of us working in science and technology, it's the 'hello world' moment we've been waiting for - the most meaningful milestone to date in the quest to date to make quantum computing a reality," Pichai wrote in a blog.
Google developed a microprocessor, named Sycamore, that packs a total of 54 qubits. Measuring about 10 mm across, it is made using aluminium and indium parts sandwiched between two silicon wafers.
In their experiment, the researchers were able to get 53 of the qubits - connected to each other in a lattice pattern - to interact in a quantum state.
They then set the quantum computer a complex task to detect patterns in a series of seemingly random numbers. It solved the problem in 3 minutes and 20 seconds. They estimated that the same problem would take 10,000 years for a Summit supercomputer - the most powerful in the world today - to solve.
"This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy for this specific computational task, heralding a much-anticipated computing paradigm," wrote the research team, led by Google AI's Frank Arute.
Hold on a qubit
While the peer-reviewed research has drawn plaudits, with MIT's William D. Oliver comparing its findings in Nature to the Wright brothers' first flights, sceptics say Google is over-selling its achievement.
Researchers at IBM , Google's main quantum computing rival, said a supercomputer with additional disk storage can solve the random number problem in at most 2-1/2 days, with greater fidelity - or accuracy.
They also said Google risked misleading the public by implying the new-style computers would replace existing ones.
"Quantum computers will never reign 'supreme' over classical computers, but will rather work in concert with them, since each have their unique strengths," Dario Gil, director of research at IBM, wrote in a blog.
Torsten Siebert, manager of the quantum computing research programme at Germany's Fraunhofer Society, said Google had achieved impressive fidelity in its experiment involving a large number of qubits.
Ultimately, he said, quantum computers were likely to work in harness with classical computers - with each playing to its strengths.
"We certainly share IBM’s concerns about the general concept of 'quantum supremacy' in relation to a truly application-orientated advancement of the field," he said, adding progress was likely to be achieved through such hybrid combinations.
(Reporting by Douglas Busvine; Additional reporting by Paresh Dave in San Francisco; Editing by Mark Potter and David Gregorio)