Google Claims ‘Quantum Supremacy’ Breakthrough

Google may have achieved a milestone in quantum computing known as “quantum supremacy”, according to an unpublished paper – although at least one rival, IBM, disputes its claim.

In a paper that briefly appeared on NASA servers last week, the search giant claimed its purpose-built quantum computer, called Sycamore, carried out a task that would be practically impossible for the most powerful existing conventional systems, an achievement known as “quantum supremacy”.

The paper’s appearance, followed quickly by its withdrawal, was reported by several news outlets, but Google has so far declined to comment and has not given a date for the paper’s formal publication.

Quantum computers, which are intended to make use of quantum effects to carry out processes far more quickly than conventional systems, have implications for a range of fields including encryption and artificial intelligence, and are being developed by the likes of Google, IBM, Intel, Microsoft and a range of startups.

‘Quantum supremacy’

To date they remain largely theoretical, but in 2012 theoretical physicist John Preskill coined the term “quantum supremacy” for the moment when quantum systems can solve a problem that is practically impossible for conventional computers.

In its paper, Google describes the use of its Sycamore system, containing 54 quantum bits, or qubits, to prove the randomness of a string of numbers.

The task would have taken the world’s most powerful computer, Summit, an estimated 10,000 years, but Sycamore solved it in 3 minutes 20 seconds, Google said in the paper, as reported by several news outlets.

“This dramatic speedup relative to all known classical algorithms provides an experimental realisation of quantum supremacy on a computational task and heralds the advent of a much-anticipated computing paradigm,” Google says in the paper, according to New Scientist.

It says the advance could be useful in fields including machine learning, materials science and chemistry.  The paper is credited to a single author, John Martinis of the University of California, Santa Barbara.

Error correction

Google and NASA announced a partnership last year to test Sycamore, and the paper appears to be a result of this agreement.

Google previously said it hoped to achieve quantum supremacy in 2017 with a 72-qubit system, but that computer proved too difficult to control, leading to Sycamore’s development.

Jim Clarke of Intel Labs said in a statement the advance is a “notable mile marker”, but cautioned that the proof-of-concept is only “mile one of this marathon”.

Daniel Lidar, an engineering professor at the University of Southern California, told the Financial Times Google’s real breakthrough was the improvements in error-correction it developed in the course of building Sycamore.  Those improvements could have more general applications, he said.

But Dario Gil, head of research at Google competitor IBM, criticised Google for its claim of quantum supremacy, telling the FT is is “just plain wrong”.

He said the work was a “laboratory experiment” designed to implement a specific procedure with “no practical applications”, and that as such it was misleading to use the term “quantum supremacy”.

Google declined to comment.