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FORTUNE.COM // JUNE .1 .19
“We’re getting in on the ground floor,”
says Vijay Swarup, vice president of re-
search and development at Exxon Mobil.
The energy giant announced a partner-
ship with IBM in January in Las Vegas, in
tandem with the Q System’s splashy debut.
Swarup’s company sees applications in mak-
ing environmental predictions, optimizing
energy grids, and generating breakthroughs
in carbon-capture technologies. “Quantum
computing can take our understanding
of nature and chemistry to a granularity
that has never been able to be done before
because the computations are just too hard,”
Swarup says.
T
HE IDEA for a quantum com-
puter has been around since at
least the ’70s. Today, the most
optimistic practitioners will
tell you that the obstacles are increasingly
engineering-related, as scientists try to
figure out how to make the machines work
reliably and at scale. As Pedram Roushan,
a member of Google’s quantum unit, puts
it, “People are still puzzled by the principle
of quantum mechanics, but they’re going to
live with it and try to put it to some use.”
In 1995, Peter Shor, a mathematician
then at Bell Labs in New Jersey, proved
that a fully functional quantum computer
could do something remarkable: It could
crack RSA encryption, a popular means
of securing private communications. He
showed that his quantum algorithm could do in minutes what
might take a regular computer the lifetime of the universe to
unravel. A year later, Lov Grover, also a Bell Labs scientist, came
up with a quantum algorithm that would allow people to swiftly
search unstructured databases. Scientists piled into the field, and
advances in hardware soon followed the breakthroughs in code.
By the mid-2000s, a team led by Robert Schoelkopf of Yale,
whose lab would eventually seed the quantum field with execu-
tives and scientists, devised an approach to quantum computing
upon which the tech world’s greatest hopes hang today. Schoelkopf
helped pioneer a so-called superconducting qubit, which uses
supercooled silicon and electrical currents to work its magic. IBM’s
machines are a direct descendant of Schoelkopf ’s lab. Rigetti Com-
puting, a California startup led by Chad Rigetti, a Schoelkopf lab
alumnus who formerly played a key role in the quantum computing
effort at IBM, builds machines of this type, including a 128-qubit
one it plans to debut later this year. Google’s and Intel’s foundations
also rest on this technology.SUPERCONDUCTING
Uses an electrical
current, flowing
through special
semiconductor
chips cooled to near
absolute zero, to
produce compu-
tational “qubits.”
Google, IBM, and
Intel are pursuing
this approach, which
has so far been the
front-runner.
ION TRAP Relies on
charged atoms
that are manipu-
lated by lasers in
a vacuum, which
helps to reduce noisy
interference that can
contribute to errors.
Industrial giant
Honeywell is betting
on this technique.
So is IonQ, a startup
with backing from
Alphabet.NEUTRAL ATOM Similar
to the ion-trap
method, except it
uses, you guessed
it, neutral atoms.
Physicist Mikhail
Lukin’s lab at Har-
vard is a pioneer.
ANNEALING
Designed to find the
lowest-energy (and
therefore speediest)
solutions to math
problems. Canadian
firm D-Wave has
sold multimillion-
dollar machines
based on the idea
to Google and NASA.
They’re fast, but
skeptics question
whether they qualify
as “quantum.”
SILICON SPIN Uses
single electrons
trapped in transis-
tors. Intel is hedging
its bets between themore mature super-
conducting qubits
and this younger,
equally semiconduc-
tor-friendly method.
TOPOLOGICAL Uses
exotic, highly stable
quasi-particles called
“anyons.” Microsoft
deems this unproven
moonshot as the
best candidate in the
long run, though the
company has yet to
produce a single one.
PHOTONICS Uses
light particles sent
through special
silicon chips. The
particles interact
with one another
very little (good),
but can scatter and
disappear (bad).
Three-year-old
stealth startup Psi
Quantum is tinkering
away on this idea.7 WAYS TO WIN THE QUANTUM RACE
There are multiple ways that quantum
computing could work. Here’s a guide to
which companies are backing which tech.FORTUNE 5 00
SMALL WORLD
From left: A scientist at IonQ’s
University of Maryland lab; an image
of an atom being manipulated in an
ion-trap computing system.