Rumors hint that Google has accomplished quantum supremacy


A leaked paper suggests that
Google has achieved a milestone known as quantum supremacy, using a quantum computer to perform a calculation
that couldn’t be achieved even with the world’s most powerful supercomputers.

It’s a hotly anticipated goal,
and one intended to mark the beginning of a new
era of quantum computation
). But it’s also largely symbolic: The calculation in question serves
no practical purpose and is designed to be difficult for classical computers,
standard computers that are not rooted in quantum physics.

On September 20, the Financial Times reported
that a scientific paper, briefly published on a NASA website before being
removed, claims that Google has built a quantum computer that achieved quantum
supremacy. It’s a benchmark that the company’s quantum researchers, led by
physicist John Martinis of the University of California, Santa Barbara, have set
their sights on
for years (SN:
). An apparent plain-text version of the paper,
posted anonymously on the site Pastebin, has since been circulating among
scientists and on Twitter. A spokesperson for Google declined to comment to Science News.

According to the Pastebin version
of the paper, Google created a quantum computer named Sycamore with 54 quantum
bits called qubits, 53 of which were functional. The researchers used it to
perform a series of operations in 200 seconds that would take a supercomputer about
10,000 years to complete.

The calculation consists of
performing random operations on the qubits and reading out the result. After
doing this many times, the researchers are left with a nearly random assortment
of numbers, one that is extremely difficult to reproduce with a classical

Despite its lack of
applications, quantum supremacy has been billed as a major breakthrough in the
quest for a quantum computer that could eventually perform useful calculations
that are not possible with classical computers. “This dramatic speedup relative
to all known classical algorithms provides an experimental realization of
quantum supremacy on a computational task and heralds the advent of a much-anticipated
computing paradigm,” the text of the Pastebin paper reads.

The machines might
eventually be capable of defeating encryption techniques used to secure certain
transmissions, such as financial transactions made by computers. But that
advance will require many more qubits and a method to correct the errors that
inevitably creep into quantum calculations. “While this is a milestone, it is
*very* far from being a quantum computer that can compute anything useful,”
physicist Jonathan Oppenheim of University College London wrote on Twitter.

Not everyone agrees that
quantum supremacy is a useful benchmark. “Quantum computers are not ‘supreme’
against classical computers because of a laboratory experiment designed to
essentially (and almost certainly exclusively) implement one very specific
quantum sampling procedure with no practical applications,” IBM’s director of
research Dario Gil wrote in a statement sent to Science News.

IBM is developing
their own line of quantum computers
(SN: 11/10/17), and researchers there prefer to talk about “quantum
which they define as “the point at which quantum
applications deliver a significant, practical benefit beyond what classical
computers alone are capable.” The new result falls short of that standard.

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Why tumbleweeds may be more science fiction than Old West


Spotting a tumbleweed
doesn’t necessarily mean you’re anywhere near the O.K. Corral.

Those dried-up, gray and
brown tangles of Salsola plants have
blown through many a Western movie, but they aren’t all that Western. You can
find the common S. tragus in Maine,
Louisiana, Hawaii and at least 42 other states. What’s more, S. tragus isn’t even native to North
America, says evolutionary ecologist Shana Welles of Chapman University in
Orange, Calif.

When the plant arrived on
the continent over a century ago, it wasn’t welcome. An 1895 agricultural
bulletin blames the accidental arrival on “impure” flax seed brought from Russia
to South Dakota during the 1870s. From there, the adaptable S. tragus rode the rails, surviving a range
of climates and really thriving in places like California’s Central Valley.
Welles, who is 5’8”, says, “I definitely have stood next to ones that were
taller than me.”

The plants are more famous
dead than alive. Even Welles, who did her Ph.D. on tumbleweeds, says, “the
flowers look like almost nothing.” The lentil-sized fruits, however, have a
certain botany-geek charm. Each one grows papery, sometimes pinkish flares of
tissue called fruit wings.

tumbleweed flowers
These tiny, pale rosettes on a tumbleweed branch are immature fruits, forming from the plant’s inconspicuous flowers.Forest and Kim Starr/Starr Environmental, (CC BY 3.0 US)

A single S. tragus plant can create more than
100,000 of those fruits, which are crucial to understanding the big hairball-like
tangles. When fruits and seeds form, the plant grows a “break here” tissue
layer that weakens the stalk at the base. Wind eventually snaps off the whole
branching architecture to blow where it will. “There is no living tissue of the
mother plant when it’s tumbling,” Welles says. A tumbleweed is just a maternal
corpse giving her living seeds a chance at a good life somewhere new.

In its North American home, S. tragus has had some improbable offspring. Never mind that the other parent of some of those progeny is S. australis, a different species with only half as many chromosomes. (It hitchhiked to the continent from perhaps Australia or South Africa.) Mismatching chromosome numbers can be a deal breaker for animals looking to mate, but plants have their ways. When tragus met australis, the latter just added an extra copy of all its DNA and the numbers worked out. Instead of a dud, a new species, S. ryanii, was born (SN: 4/12/16).

Welles wondered if the
newbie plant was a super-tumbler. Biologists have predicted that such hybrids
should have extra vigor in terms of plant growth. Maybe. In one of two years of
experiments, the cross-species tumbleweeds averaged 5.8 kilograms of greenery versus roughly three
kilograms for each parent, Welles and geneticist Norman Ellstrand of the
University of California, Riverside reported online July 13 in AoB Plants. These tumbleweeds and their bold
genetics may be less at home in tales of the gunslinger West than in a sci-fi
opera of romance at first contact.