Our research
The Quantum Hacking group works in the field of quantum cryptography and quantum information.
In quantum information science the information unit is not a bit, but rather a quantum bit – qubit.
A qubit may not only be zero or one, but also zero and one simultaneously!
In our work, we use photons as physical representation of qubits.
Quantum cryptography is a method of secure communication using qubits.
Such communication is based on the Heisenberg uncertainty principle. If an eavesdropper listens to qubits, she changes them, which is inevitably noticed by the legitimate users.
That is, any attempt of eavesdropping will be caught (in theory).
Our task is to make sure eavesdropping also gets caught in practice. In our daily work, we scrutinize implementations of quantum cryptography.
First, we play the role of the eavesdropper and try to hack quantum cryptosystems by taking advantage
of non-ideal behavior of the present-day quantum cryptographic hardware. Naturally, we often do find security problems.
Then, we suggest countermeasures, either practically by modifying the setups,
or theoretically by modifying the way of communicating. This is an iterative process. It should eventually make quantum cryptosystems harder to crack,
ultimately approaching the goal of absolute security.
Hacking cryptographic hardware
Practical implementations of quantum cryptography are quite complicated, and often leave loopholes to the eavesdropper. During the last few years, we have studied several hardware loopholes:
We also introduced faked-state attack, a general type of attack that exploits imperfections in Bob’s optical scheme.
Security proofs
How can we make a system secure when there are imperfections?
With the rules of quantum mechanics, we can prove security even in the presence of non-ideal equipment.
We try to incorporate different kinds of imperfections into the security proofs.
Our ultimate goal is a completely secure system, where all imperfections that cannot be eliminated are taken into account.
Quantum key distribution system
Since other research groups and commercial manufacturers alike do such a poor job at producing hack-proof systems (as we see so far :), we have to take this task ourselves.
In our lab, we are building our own quantum cryptosystem, with the explicit goal to address all known loopholes and security issues.
Distinguishing quantum states
Non-orthogonal quantum states cannot be reliably distinguished by a measurement.
This uncertainty limits the amount of information Alice can send Bob using non-orthogonal qubits.
We are trying to find measurements which distinguish non-orthogonal states with the smallest probability of error,
and measurements which optimize Alice’s and Bob’s mutual information.
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Collaborations
We have ongoing partnership (visits by students and researchers, equipment and information exchange) with
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In addition, we have a collaboration agreement with Institute of quantum computing at the University of Waterloo, Canada.
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| |  | Testing eavesdropping experiment in lab | |
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