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quantum technologies programs, vary-
ing from millions to billions, including
those of Australia, Canada, China, EU,
Japan, Netherlands, Russia, Singapore,
U.K., U.S. At the same time, major in-
dustrial players such as Google, IBM,
Microsoft, Intel, Atos, Baidu, Alibaba,
Tencent along with numerous smaller
and bigger quantum start-ups have ini-
tiated labs developing quantum hard-
ware and software. This has led to what
is now called “the second quantum
revolution,” where the ability to ma-
nipulate quantum systems as desired
is leading to an era in which a variety
of new technologies will appear and, in
certain cases, could potentially replace
existing solutions.

Arguably, the most important quantum technology will be the development of computation devices that exploit quantum phenomena, which we refer to as quantum computers. Quantum computers are likely to become a disruptive innovation as they can offer considerably greater computational power than their classical counterparts.

Here, we must stress that this is not
something that will become relevant
in the far future. Impressive quantum
technological achievements are al-
ready available. To name two recent ex-
amples: Google’s latest quantum pro-
cessor “Bristlecone” has a record of 72
qubits with very low error rates, and is
expected to be larger in size than what
the best classical supercomputers can
simulate. 3 Satellite quantum key distri-
bution has been realized, enabling in-
formation theoretic secure encryption
over distances of 7600km (interconti-
nental) and used as basis for a secure
teleconference between the Austrian
Academy of Sciences and the Chinese
Academy of Sciences. 27

Quantum cyber security. The devel-
opment of large quantum computers,
along with the extra computational
power it will bring, could have dire
consequences for cyber security. For
example, it is known that important
problems such as factoring and the dis-
crete log, problems whose presumed
hardness ensures the security of many
widely used protocols (for example,
RSA, DSA, ECDSA), can be solved ef-
ficiently (and the cryptosystems bro-
ken), if a quantum computer that is
sufficiently large, “fault tolerant” and
universal, is developed. 35 While this
theoretical result has been known
since the 1990s, the actual prospect of
building such a device has only recent-
ly become realistic (in medium term).
However, addressing the eminent risk
that adversaries equipped with quan-
tum technologies pose is not the only
issue in cyber security where quantum
technologies are bound to play a role.
Quantum cyber security is the field
that studies all aspects affecting the se-
curity and privacy of communications
and computations caused by the devel-
opment of quantum technologies.

Quantum technologies may have a negative effect to cyber security, when viewed as a resource for adversaries, but can also have a positive effect, when honest parties use these technologies to their advantage. The research can, broadly speaking, be divided into three categories that depend on who has access to quantum technologies and how developed these technologies