Quantum leap for photonic modulation

Researchers at Stanford have made a breakthrough which could give quantum cryptography, information processing, and even memory storage a big boost, by modulating the time profile of a single photon.

Quantum cryptography is something the likes of IBM, HP, Toshiba and NEC have all been studying closely for several years.

As a technology, it generally guarantees secure communication, enabling two parties to generate a secret shared random bit string, which is then used as a key to encrypt and decrypt messages.

The key to making it work, however, is encoding information in quantum states, usually in the form of photons.

"Single photon physics provides secure communication. If I do coding with photons, eavesdropping is not possible. A person who tries to eavesdrop, destroys the photon in the process," said Dr. Steve Harris who is carrying out the research.

Harris’ researchers managed to make an entangled photon wave packet of nearly a microsecond long by using "slow light" and "electromagnetically induced transparency."

The current research being undertaken at Stanford deals with amplitude modulation, but Harris says the next phase will concentrate mainly on phase modulation which is a bit more efficient as it doesn’t lose photons in the tracking process.

It could also potentially prove that a fair few bits of data could be beamed from here to there as part of a single photon’s phase.

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