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New Approach ­ses 'twisted Light' to Increase the Efficiency of Quantum Cryptography Systems

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Artist's conception of 'twisted light.'

Researchers at the University of Rochester have achieved a breakthrough which they say could help increase the efficiency of quantum cryptography.

Credit: University of Rochester NewsCenter

University of Rochester researchers have developed a way to transfer 2.05 bits per photon by using "twisted light," a breakthrough they say could help increase the efficiency of quantum cryptography.

The new method uses the orbital angular momentum (OAM) of the photons to encode information, rather than the more commonly used polarization of light.

The researchers, led by Mohammad Mirhosseini, created a proof-of-principle experiment showing that using OAM to encode information rather than polarization could lead to high-dimensional quantum key distribution (QKD).

The researchers were able to encode a seven-dimensional "alphabet" using both the OAM of the photons and their angular position. These two photon properties form mutually unbiased bases, which are required for QKD.

The researchers demonstrated the new system can generate and detect information at a rate of 4kHz and with 93-percent accuracy.

Moving forward, the researchers hope to realize secure communications at GHz transmission rates, which is desirable for telecommunication applications.

"Unlike with polarization, where it is impossible to encode more than one bit per photon, 'twisted light' could make it possible to encode several bits, and every extra bit of information encoded in a photon means fewer photons to generate and measure," Mirhosseini says.

From University of Rochester NewsCenter
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Abstracts Copyright © 2015 Information Inc., Bethesda, Maryland, USA


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