Secure Quantum-Based Data Encryption

In the inevitable and not-so-far quantum-future that awaits us, quantum encryption techniques will be of utmost importance. They use individual photons as an extremely secure way to encode data, but as with any other encryption method, there is a downside to a quantum encryption too, which is the disability to emit photons at high rates.

“One of the most important figures of merit for single-photon sources is brightness – or collected photons per second – because the brighter it is, the more data you can transmit securely with quantum encryption,” said Yousif Kelaita, of Nanoscale and Quantum Photonics Lab, Stanford University, California.

Now, Kelaita and colleagues have managed to create a new type of light-enhancing optical cavity that is ultra small – only 200 nanometers tall and 100 nanometers across. Their new nanocavity system is able to significantly increase the emission brightness of quantum dots, which are nanometer-scale semiconductor particles that can emit single photons.

The researchers developed the new nanocavity system by using highly reflective silver to coat the sides of a nanoscale semiconductor pillar sitting on a substrate. Why silver? Because it makes the light bounce around inside the nanopillar, essentially turning it into an ultra-small optical cavity. And because the same design concept can be used to build nanocavities from other materials, they can be tailored for different single-photon emitters.

The new nanoscale system represents a step toward brighter single-photon sources, which could help the development of a truly secure quantum-based encryption.

Reference:

The Optical Society (http://www.osa.org/en-us/about_osa/newsroom/news_releases/2016/ultra-small_nanocavity_advances_technology_for_qua/)