A CSIR National Laser Centre team has made a startling discovery in quantum research that may pave the way for more robust quantum communication systems. The team, under the direction of Prof Andrew Forbes, showed that quantum entanglement between particles of light could be transmitted through an obstacle. The work was published this week in Nature Communications
Entanglement is that spooky phenomenon associated with quantum systems, which has no analogue in our familiar classical world. While the weirdness of entanglement is not fully understood, it is nevertheless a key resource exploited in many quantum systems, for example, secure quantum communication and quantum imaging. Unfortunately it is very fragile and is easily lost. Once lost, the quantum nature of the system under study is also lost.
The team showed that this lost entanglement may in some cases be recovered, by using particular patterns of light for the detection of the entanglement. First they deliberately disrupted the entanglement by placing an obstacle in the path of the light, destroying the entanglement by reducing it to noise levels. Using Bessel beams, they showed that the lost quantum entanglement could self-heal and fully recover from the noise. The results suggest that a simple choice of measurement has a large impact on the degree of entanglement of a quantum system. The team believes that there are significant benefits to using Bessel beams for secure quantum communication systems and are pursuing this in collaboration with other leading international groups.
Melanie McLaren was the lead student on the project. She is presently completing her PhD on practical quantum protocols and has built the first quantum entanglement system in Africa, and one of the few high-dimensional quantum experiments in the world. Melanie recently won awards at both national and international conferences for her work.