With new technology, quantum encryption gets less costly and more accessible
23 Jul '20
Scientists at ITMO University in St. Petersburg appear to have discovered a way of modifying quantum key distribution (QKD) protocols. The technology is expected to reduce the cost of and facilitate access to mass QKD networks. With the new approach, the conventional fiber optic communications infrastructure is believed to be quite enough to have the above achieved.
Quantum key distribution, or simply quantum encryption, is apparently one of the most reliable ways of encoding data known today. In a network that uses the technology, a quantum signal intruders would find tough to intercept is used as the data carrier.
“To make QKD possible, deliberately weakened laser light is used, as a rule, in which the average number of photons is below one. The emission demonstrates quantum effects that prevent a third party from penetrating the channel, cracking data, and walking away unpunished,” said Eduard Samsonov of ITMO’s Department of Photonics and Optoinformatics, one of the researchers.
Demand for QKD systems has been increasingly on the rise. The technology is not without flaws, however. The major one is the complexity and the cost of equipment this method of data transfer requires. In addition, the capabilities offered by the current fiber optic communications infrastructure seem to be deficient when it comes to creating such systems.
Every problem has a solution
An ITMO University team claims it has successfully addressed the problems. Their continuous-variable quantum key distribution (CV-QKD) protocol uses multimode coherent states generated on subcarrier frequencies (placed on both sides of the carrier frequency) of the optical spectrum. The scientists proposed a coherent detection scheme where power from a carrier wave was used as a local oscillator. The key novel feature of the new protocol is generating states using electrooptical phase modulator.
With emission propagated on a certain optical frequency, phase modulation causes the formation of subcarrier frequencies that carry information about the phase of a signal to be transferred. If modulation rate is low, light emission on such subcarrier waves will also be low.
So, the team has introduced what could be referred to as extra modulator, similar to the one that generated the original signal on the subcarrier frequencies but having an increased modulation rate.
The signal passes through the modulator again, which results in the generating of new additional subcarriers interacting with the ones that came from the transmitter. The technique is reported to keep the system reliable and quantum encryption highly protected.