By S Gray
Two papers that have been published in
the last fortnight by Physical Review Letters have renewed my
interest in the field of Quantum Cryptography. Interestingly, the
papers are involved in very different aspects of this field.
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| Credit: http://www.iqst.ca/media/html/macgregor_files/macgregor02.jpeg |
The first paper,
Measurement-Device-Independent Quantum Key Distribution over 200 km,
brings the practical uses of Quantum Key Distribution (QKD) much
closer. QKD is a means of distributing encryption keys in such a way
that if a third party tries to view the key while it is in route,
their observation will effect the quantum state and can be detected
by the intended party. The team, led by Jian-Wei Pan and Qiang Zhang
from the University of Science and Technology of China in Hefei, have
implemented this technique over a 200 km fibre optic cable – four
times further than previous attempts. They have also achieved speeds
potentially 500 times faster than previous setups.
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| Conceptual illustration of a photon-based qubits
Credit: http://images.iop.org/objects/phw/news/17/6/10/PWqua_120613.jpg
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The second paper, Experimental Realization of a One-Way Quantum Computer Algorithm Solving Simon’s Problem, showcases the first time that an algorithm has been
successfully run on a Quantum Computer. Although Simon's algorithm
has no practical applications, the experiment is a major step forward
for Quantum Computing and the implementation other quantum software
such as Shor's algorithm – potentially capable of cracking
encryption keys exponentially faster.
Sources:
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