Dr. Anne Broadbent – Building Secured Quantum Computing
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Dr. Anne Broadbent – Building Secured Quantum Computing


[Beaker bubbles up] [Start of music] My name is Anne Broadbent. I’m a
professor in the Department of Mathematics and Statistics at the
University of Ottawa. I would like to introduce my team. Rabib Islam, Sébastien Lord, Supartha Podder and Daniel Puzzuoli. Quantum mechanics describes the way that
particles behave at the atomic level and physics tells us that at that level or
intuition completely breaks down. That is that there are quantum phenomena that
are really interesting to study and look at and that’s what we’re doing in our
research group. Conventional computers are used in our everyday lives and the
basic unit of information for these computers is the bit. It’s a discrete
state: it’s either 0 or 1. In contrast to this, in quantum computers the basic
level of information is called the qubit and this is in a continuum of states
between 0 and 1. Actually it’s in both states potentially
at the same time. This is called a superposition. So what our research team
is doing, we’re looking at quantum phenomena and trying to take advantage
of these for communication and information processing tasks. One of the
really cool things of quantum mechanics is that it predicts something called the
no-cloning theorem. According to this theorem it’s impossible to make two
perfect copies in general of an unknown quantum state. At first this sounds
really useless and annoying because our everyday intuition about copying
information doesn’t hold. For instance, it would not be possible to make a backup
copy of quantum information. But where some people see a challenge we see a new
opportunity. So we’re trying to take advantage of the no-cloning theorem and
other quantum phenomena to have more secure crypto systems which will allow
for more secure communication and more secure information processing. Quantum computers are computers that
process information at the quantum level. They are known to give access to
incredible computational power and to solve some problems efficiently by a
quantum methods and these solutions are more efficient than any conventional
computer could ever hope to achieve. So one of the quantum algorithms that is
known is the factoring algorithm; i.e. given a large number how could we
decompose it into its prime factors. The consequences of this quantum
algorithm are huge because most of current security that we use over the
Internet is based on the assumption that factoring numbers is difficult. So in the
advent of quantum computers and many experts believe that it’s just a matter
of time, we will have to completely retool our information infrastructure in
order to be secure against these quantum attacks.
Thus we urgently need to find a solution to the information security question in
the presence of quantum computers. And one solution, which already exists and
is already even implemented is quantum key distribution. This is a method to
securely distribute messages among parties on a network using quantum
information as the information carrier. Don’t get me wrong mathematics is very
much involved here. In fact, there are some profound mathematical results that
are used in the security analysis of the techniques. However, the underlying
assumption here would be a physical assumption, the correctness of quantum
mechanics, versus in the case of conventional computing a computational
assumption, the hardness of factoring. Another question that our team is
looking at is the question of delegating quantum computations. Here we imagine a
cloud quantum computing service that has a quantum computer that is accessible
remotely and the question is: Could users remotely access the service while
maintaining privacy of their data and of their algorithms? We’ve come up with
many solutions including solutions to verify the correctness of the
quantum computation. We’re also looking at problems of uncloneable encryption,
certified deletion, and many other consequences of the no-cloning theorem. Given the steady progress in building quantum computers we’re hoping that our
research will contribute to more secure digital society.

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