The Era of Quantum Computing Microprocessors Dawns
Research teams all over the world have been exploring different ways to design a working computer that can integrate quantum interactions.
Technology Briefing

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Transcript
Many
of the toughest problems in medicine, chemistry, nanotechnology and
cybersecurity, simply can't be solved using conventional digital computing
technology.
That's
where quantum computing comes in.
And
that's why, when we wrote Ride the Wave, we
identified quantum computing as one of the 12 crucial technologies needed to
fully realize the potential of the Digital TechnoEconomic Revolution.
Unfortunately,
creating a generalpurpose quantum computer has proven to be overwhelmingly
difficult. And
the resulting hardware prototypes have proven about as reliable and
maintainable as the original vacuum tube technology used in the Eniac
system.
Today's
only commercial quantum computer is from DWave Technologies; it uses a highly
specialized approach called "quantum annealing" to solve a narrow range of
optimization problems for cuttingedge companies, like Google and
LockheedMartin, who are willing to pay over $10 million per machine.
In
the meantime, research teams all over the world have been exploring different
ways to design a working computer that can integrate quantum
interactions.
But,
a complete engineering design to realize this on a single chip has been
elusive.
However,
that's about to change. It seems we are on the verge of a technological leap
that could be as deep and transformative as the original microprocessor release
in 1973.
Engineers
at the University of New South
Wales, or UNSW, believe they have solved the
problem by reimagining the silicon microprocessors we know, to create a
complete design for a quantum computer chip that can be manufactured using
mostly standard industry processes and components.
The
new chip design, published recently in the journal Nature Communications, involves a
novel architecture that allows quantum calculations to be performed using
existing CMOS technology, the basis for all modern chips. As
remarkable as they are, today's computer chips cannot harness the quantum
effects needed to solve the important problems that quantum computers
will.
The
power of the new design is that, for the first time, it charts a conceivable
engineering pathway toward creating a machine with millions of quantum bits, or
qubits.
To
solve problems that address major global challenges  like secure encryption
or complex diseases  it's generally accepted that we will need millions of
qubits working in tandem.
To
do that, we will need to pack qubits together and integrate them, like we do
with modern microprocessor chips. That's what this new design aims to achieve.
This
design uses conventional silicon transistor switches to 'turn on' operations
between qubits in a vast twodimensional array, using what engineers call "a
gridbased word and bit select protocol," which is similar to that used to
select bits in a conventional computer memory chip.
By
selecting electrodes above a qubit, they can control a qubit's spin, which
stores the quantum binary code of a 0 or 1.
And
by selecting electrodes between the qubits, twoqubit logic interactions, or
calculations, can be performed between qubits.
A
quantum computer exponentially expands the vocabulary of binary code used in
modern computers by using two "spooky principles" of quantum physics  namely,
'entanglement' and 'superposition.'
Qubits
can store a 0, a 1, or an arbitrary combination of 0 and 1 at the same time. And
just as a quantum computer can store multiple values at once, so it can process
them simultaneously, doing multiple operations at once.
This
allows a universal quantum computer to be millions of times faster than any
conventional computer when solving a wide range of important problems.
But
to solve these complex problems, a useful universal quantum computer will need
a large number of qubits, possibly millions.
That's
because every type of qubit we know is fragile and even tiny errors can be
quickly amplified into wrong answers. So,
we need to use errorcorrecting codes which employ multiple qubits to store a
single piece of data.
The
UNSW chip blueprint incorporates a new type of errorcorrecting code designed
specifically for spin qubits, and involves a sophisticated protocol of
operations across the millions of qubits.
This
design represents the first attempt to integrate into a single chip all of the
conventional silicon circuitry needed to control and read the millions of
qubits needed for realworld quantum computing.
The
researchers expect that modifications will still be required to this design as
they move towards manufacture. But
all of the key components that are needed for quantum computing are now here in
one chip.
And
that's what will be needed to make quantum computers the workhorses for
calculations that are well beyond today's computers.
The
effort to design and build such a universal quantum computer has been called
the 'space race of the 21st century.'
That's
because, for some challenging problems, they could find solutions in days, or
maybe even hours, which would take millions of years using today's best
supercomputers.
Today,
there are at least five major quantum computing approaches being explored
worldwide:
silicon
spin qubits,
ion
traps,
superconducting
loops,
diamond
vacancies, and
topological
qubits.
UNSW's
design is based on silicon spin qubits.
The
main problem with all of these approaches is that there has been no clear
pathway to scaling the number of quantum bits up to the millions needed without
the computer becoming a huge system requiring bulky supporting equipment and
costly infrastructure.
The
UNSW design, for the first time, incorporates everything needed to integrate
the millions of qubits needed to realize the true promise of quantum computing
on a single chip.
That's
why UNSW's new design is so exciting.
By
relying on its silicon spin qubit approach  which mimics the solidstate
devices in silicon that are the heart of the $380 billion a year global
semiconductor industry  it shows how to dovetail spin qubit error correcting
code into existing chip designs, enabling true universal quantum computation.
Unlike
almost every other major group, the UNSW quantum computing effort is
obsessively focused on creating solidstate devices in silicon, from which all
of the world's existing computer chips are made.
And
they're not just creating ornate designs to show off how many qubits can be
packed together; they are aiming to build qubits that could be easily
fabricated  and scaled up. This
design represents a big leap forward in silicon spin qubits.
It
was only two years ago, in a paper in Nature, that its
developers revealed the creation of a twoqubit logic gate  the central
building block of a quantum computer.
It
showed, for the first time, how quantum logic calculations could be done in a
real silicon device.
Those
were the first "baby steps," demonstrating how to turn this radical quantum
computing concept into a practical device using components that underpin all
modern computing.
And
now the UNSW team has a blueprint for scaling that up dramatically. They've
been testing elements of this design in the lab, with very positive results.
They just need to keep building on that.
Given
this trend, we offer the following forecasts for your consideration.
First, until reliable
generalpurpose hardware is available quantum computing will remain a sleeping
giant.
Quantum
computing is still at the stage where digital computing was in the late1940s:
laboratory prototypes and conceptual designs with only theoretical
applications.
That
was all changed by the invention of solidstate transistor logic gates. But,
once a reliable quantum processor exists, software and new applications will
explode.
Second, over the next
five years, companies and nations will make lots of small bets on quantum
computing and a few will payoff big. For
example, in August 2017, the UNSW researchers launched Silicon Quantum
Computing Pty Ltd. It's Australia's first quantum computing company, intended
to advance the development and commercialization of the team's unique technologies.
And
it just struck an $83 million deal to develop, by 2022, a 10qubit prototype
silicon quantum integrated circuit. That
will represent the next big step toward building the world's first quantum
computer in silicon.
Third,
it will be at least a decade before we know for certain which of the six
computing qubit technologies will dominate quantum computing in same way CMOS
dominates conventional computing.
The
outcome will depend on which technological approach ultimately creates the most
efficient universal quantum computer that can be scaled up, at a reasonable
cost, to solve problems beyond the capabilities of conventional
supercomputers.
And
history is replete with examples where it's not the best technology that gains
a foothold, or the cheapest, or even the one that scales up fastest.
It
may possibly take several iterations; remember, it took four generations of
computers to get from bulky vacuum tube circuitry and magnetic drum memory to
the multicore CPUs with silicon semiconductor logic gates, common today.
