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In quantum cryptography, quantum mechanical principles are utilized so that two parties, often referred to as Alice and Bob, may exchange private information in a secure way. Alice and Bob send quantum states to each other to generate a private key. An eavesdropper, Eve, trying to measure on the quantum states cannot obtain any information of the key without being exposed.
Quantum cryptography has been proven to bee completely secure in theory, as long as the quantum-bit error rate is sufficiently low. In practice one must also take into consideration security loop holes due to non-perfect equipment. Current areas for the research is:
- General quantum information theory
- Theoretical safety proofs with imperfect equipment
- Attacks using fake states
- Large pulse attacks, in which Eve interrogates Alice and Bob by external bright pulses mixed into the optical channel.
For more information, see the web page of the quantum hacking group
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Laboratory fasilities
The equipment for testing of safetyloops within quantum cryptography is a part of the coherent lab.
Projects
Below you find a list of the projects connected to the quantum cryptography group. For a complete list of projects at the electrooptics group, see projects.
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- Distinguishing quantum states
Supervisor: Johannes SkaarPhD student: Øystein MarøyNon-orthogonal quantum states cannot be distinguished with a 100% certainty. We attempt to find optimal measurements to distinguish such states with highest possible certainty. The problem is treated both in finite- and infinite dimensional Hilbert spaces. Analytical, numerical and algebraic methods are invoked. The results will be of relevance to quantum information theory and quantum cryptography.
- Safety analyses in quantum cryptography
Supervisor: Johannes SkaarWe do security analysis og quantum cryptography systems with error in both source and detector. Our goal is to include all kinds of errors such as bit and basis leakage, bit-dependent detector efficiency, basis dependent couplings between different modes, etc. We want to do a complete security proof where all kind of errors are either eliminated or taken care of by privacy amplification.
