NSA keys into quantum computing

phy sic swor ld.com
News & Analysis
NSA keys into quantum computing
The US National Security Agency
(NSA) has a classified programme
to build a quantum computer that
can break modern Internet security, according to documents leaked
by the former NSA contractor
Edward Snowden. The documents,
which were published last month in
redacted form by the Washington
Post, have surprised few physicists
working in the field. However, they
have led to speculation about the status of NSA research and a renewed
debate on the risks of developing
quantum computers.
Quantum computers are devices
that rely on quantum phenomena
such as superposition, in which a
system exists in multiple states at
once, and entanglement, in which
the states of two systems become
inextricably linked. Unlike classical
computers, which store bits of information in definite values of 0 or 1,
quantum computers store information in quantum bits, or qubits, which
are a superposition of both. When
qubits are entangled, any change
in one immediately effects changes
in the others. Qubits can therefore
work in unison and solve certain
complex problems much faster than
their classical counterparts.
Some of these problems are purely
scientific in nature, such as simulating molecules inside biological cells,
which could allow researchers to
develop more effective drugs. But
one problem quantum computers
are expected to be most proficient at
is factorizing large numbers. If successful, this would allow supposedly
secure information on the Internet
to be deciphered, including banking transactions, private messages
and government files. Although in
principle classical computers could
perform the same deciphering, the
process would usually take so long
as to be unfeasible.
I n 2 0 0 6 the NSA open ly
announced the creation of a joint
institute with the University of
Maryland in College Park and the
National Institute of Standards and
Leaked documents suggest that the US National Security Agency is developing quantum computers to
crack cryptography codes, but what progress has the agency really made? Jon Cartwright investigates
Technology in Gaithersburg, both
in the US, to develop quantum technology, including quantum computing. But the new documents reveal
an additional classified effort at
Maryland with the express purpose
of breaking data encryption. They
state that the NSA wants to build
“a cryptologically useful quantum
computer” as part of a programme
titled “Penetrating Hard Targets”,
which the Post claims has a budget of
$79.7m (£48m).
Many physicists working in the
field of quantum information believe
quantum computing is exactly the
sort of technology one would expect
the NSA to develop. “If you put my
level of surprise on a scale from zero
to 10, where 10 is very, very surprised,
my answer would be zero,” says Raymond Laflamme, a leading quantuminformation theorist who is based at
the University of Waterloo in Canada.
“If they were not doing it, they would
not be doing their job.” Even so, the
news has confirmed for many others
how important it is to find other ways
to make digital information secure.
Unbreakable codes?
Encrypted information on the Internet exists on pages whose URL
begins with “https://” as opposed to
“http://”. It is based on public-key
cryptography, which allows someone
to send information to someone else
Listening in
The US National
Security Agency is
allegedly developing
quantum computers
with the aim of
breaking quantum
cryptography codes.
by encoding it with a publicly available key. Although anyone on the
Internet could intercept and read the
message in its encrypted form, only
the receiver, who holds a special, private key, can decipher it.
The most common type of publickey encryption is RSA, which was
invented by the cryptographers
Ron Rivest, Adi Shamir and Len
Adleman in the late 1970s. In RSA
encryption, both the public and private keys are derived from a pair of
large prime numbers, the product
of which anyone can find out. If you
know the formula, you can in theory
work backwards, factorizing the
product until you discover the primes
– but it is only realistically solvable if
your computer is powerful enough.
Quantum computers could do
that kind of factorization – and as
Laflamme points out, it does not
matter that they have not been properly realized yet. Information on
the Internet can easily be stored,
which indeed the NSA – as well as
the UK Government Communications Headquarters (GCHQ), other
intelligence agencies and private
cloud-computing companies – is
doing routinely anyway. That means
information encrypted today could
be deciphered in 10 years’ time – or
whenever quantum computers are
finally in use.
How much of a problem that
poses depends on the sort of information you are encrypting, explains
Laflamme, who gives the example
of someone using a computer to buy
something with a credit card. The
development of a quantum computer is not a threat because in 10
years you will have changed your
credit card, and unless you are buying something illegal, you will not
care that the NSA knows. “But what
if you’re sending the explanation
of a new type of classified technology, one you want to keep secret for
20 years?” asks Laflamme. “Well,
then it’s problematic.”
There are methods to future-proof
the transfer of secret information.
P hy sic s Wor ld  F ebr uar y 2014
News & Analysis
phy sic s wor ld.com
One is to create a communication
network independent of the Internet through which users can share
secret keys, which can then be used
to encrypt and decipher messages on
the Internet. The security of such networks can be improved further with
quantum key distribution (QKD),
which in theory guarantees the security of the key transfer – although the
latest documents also reveal that the
NSA is attempting to exploit practical loopholes in this, too, under a programme known as “Owning the Net”.
Vadim Makarov, who himself studies flaws in practical QKD systems at
the University of Waterloo, says that
cryptographers are also looking into
classical “quantum-safe” encryption
algorithms for use on the Internet.
Like quantum computing, however,
quantum-safe encryption and foolproof QKD systems, which cannot be
cracked at all, are also taking time to
develop and implement. “I just hope
we won’t be too late,” he says.
Secret race
The NSA has not publicly responded
to the leaks, but another question
raised by the NSA documents is
whether the agency could be further
ahead in the development of quantum computing than major labs. The
main reason functional quantum
computers are expected to be many
years away is that it is still very difficult to control qubits while protecting them from external interference
that can all too easily destroy them.
Moreover, no-one is yet sure what
type of qubits are most likely to be
practical, with physicists exploring
types made from trapped ions, photons and superconducting circuits, to
name but three.
According to the documents, the
NSA expected its scientists to have
demonstrated “dynamical decoupling and complete quantum control
on two semiconductor qubits” by the
end of September 2013. Purely on
numbers, the agency would appear to
be lagging behind major labs such as
the Institute for Experimental Physics at the University of Innsbruck in
Austria, which demonstrated entanglement of 14 atomic qubits as far
back as 2010. On the other hand,
control of qubits made of the semiconductor silicon is less advanced,
with only single silicon qubits having been openly demonstrated since
2012. If the NSA has already succeeded in achieving control of two
silicon qubits, then it may be ahead
in that particular race.
The semiconductor mentioned in
It is still very
to control
qubits while
them from
that can all too
easily destroy
UK splashes out £270m on quantum technology
P hy sic s Wor ld  F ebr uar y 2014
close eye” to ensure the cash is not
simply siphoned off from budgets
earmarked for other scientific fields.
The detailed mechanism for distributing the funding among UK
researchers is still being discussed,
although it is likely to involve the
UK’s research councils, the Royal
Society and the Royal Academy
of Engineering. However, Jeremy
O’Brien from the University of Bristol, who also helped to get the initiative off the ground, says the UK must
properly co-ordinate the new investment. “Fragmentation into small
chunks will be the enemy of progress
and ultimately could hinder the creation of wealth,” he says.
But participants are optimistic about what the initiative can
achieve. “There is real potential for
long-term transformational change
in some information-related technologies, deriving from a complete
re-conception of design principles
underpinning their operation,” says
Ian Walmsley from the University
of Oxford.
about £30m per year will go to the
Technology Strategy Board – the
UK’s national innovation agency
– to support immediate commercialization of technology. There will
also be money for PhD students and
postdocs, while some £4m will go on
Quantum commerce equipment for the new Advanced
Metrology Laboratory being built
The UK has
at the National Physical Laboratory.
announced it will
The quantum-physics initiative,
establish a network
which has involved careful behindof quantumthe-scenes negotiations between the
technology centres
to convert quantum- UK physics community, government
physics research into and industry, was formally put to
Osborne last year by a group of physcommercial
icists led by Peter Knight from Impeproducts.
rial College London. Knight, who is
the immediate past president of the
Institute of Physics, which publishes
Physics World, says that the prospect
of an extra £270m for quantum technology is “highly exciting”. However,
he adds that he will be “keeping a Matin Durrani
Further details have emerged of a
new £270m initiative being funded
by the UK government to convert
quantum-physics research into commercial products. The five-year initiative, which will include the creation
of a network of quantum-technology
centres, was one of a number of
measures revealed by the government in its Autumn Statement in
early December 2013 to boost the
UK’s science base. The chancellor George Osborne said that the
money was “additional investment”
in research and that science was a
“personal priority” of his.
The initiative, which will begin
in 2015, will focus on areas such
as chip-scale atomic clocks for
improved GPS communication,
quantum-enabled sensors, quantum
communication and quantum computing. Some cash will go to existing
university research groups, while
the documents could also refer to
types of semiconductor that turn
superconducting in certain regimes.
But experimental quantum physicist Jonathan Home of ETH Zurich
in Switzerland believes the NSA is
indeed pursuing a regular semiconductor such as silicon, because the
“dynamical decoupling” also mentioned – a type of noise mitigation
– is not usually applied to superconducting qubits. If the agency is pursuing silicon, that might be because
it is easy to build large arrays of
silicon devices, Home says. But he
adds that it is not so easy with silicon
to implement the error correction
that would make any devices function like proper qubits. “If I were an
NSA manager, maybe I know the
solid-state can be scaled up, so I pick
that. But maybe I haven’t thought so
hard about actual quantum computing,” he says.
If the NSA is developing quantum
computers, does that mean that other
intelligence agencies such as GCHQ
are too? Physicists contacted by
Physics World were not sure whether
an agency outside the US would have
the resources. But one point is obvious: over every development in quantum computing in the coming years,
the spies will be watching.