Physicists Test Quantum Cryptography For Handheld Mobile Devices: Quantum cryptography uses the laws of physics to guarantee the secrecy of messages sent from one location to another. It is one of the few quantum technologies that is become mature enough to make the leap from the laboratory to the commercial world.
So governments, the military and commercial organisations such as banks are all interested having this kind of perfect secrecy. And indeed a number of companies have cropped up in the last 10 years to sell the service.
One problem is that quantum cryptography is only possible between places that have the kind of gear usually only found in quantum optics laboratories. It generally requires that both the transmitter and receiver have a source of single photons, a way of controlling and modifying individual photons and superconducting photon detectors.
What’s more, the equipment at each end has to be carefully aligned so that both parties are able to detect the polarisation of the photons they send. And if there is any noise that changes the polarisation of the photons, the cryptography simply doesn’t work.
That scuppers any possibility of using quantum cryptography with handheld devices which would obviously be difficult to align.
Today, Jeremy O’Brien at the University of Bristol and a few pals reveal a way to solve this problem which they say could make quantum cryptography available in handheld machines.
In the new technique, only one of the parties, Alice say, needs to have the quantum optics gear such as a source of photons and so on. Alice creates the photons and then sends them down an ordinary optical fibre to Bob, the other party.
Bob, merely modifies the photons to encode them with information before sending them back to Alice. This dramatically simplifies the equipment Bob requires, allowing it to fit in a handheld device.
O’Brien and co also use a robust form of quantum key distribution that does not require Alice and Bob to align their equipment before making a measurement.
– por MIT Technology Review
– Tags: criptografía cuántica, óptica –
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