Quantum Entanglement and Communication

It’s about time that we heard some good news.

On the 15th of June 2020, China made a breakthrough in the field of quantum mechanics. They demonstrated quantum entanglement - a method of intertwining two particles so that measuring properties of one can tell you about the other. This has been done in the past, however, what makes China’s achievement significant is that they achieved this between a particle on earth and one in orbit.

What is Quantum Entanglement?

Quantum entanglement is the phenomenon where two particles are connected in such a way that when you observe one of them, you can get information about the other. The easiest of the particles that can be entangled are photons (i.e particle form of light). When observing, the state of one particle is the aspect that is measured. 

When light travels it oscillates. It behaves like a wave and a particle at the same time.

Now this oscillation can be either in one plane or many planes. When it happens in one plane, it is called polarised light and when it happens in many planes, it is termed as unpolarised.

Making the light oscillate in only one plane is called polarisation. If two photons are entangled, their polarisations are linked.

Take two photons, one that oscillates up and down and another that oscillates left and right.

If these two photons are entangled, that means that if you changed the direction in which one of them is oscillating, the other would change its direction by the same amount.

This happens regardless of however far apart these particles may be. Albert Einstein called this ‘spooky action at a distance’.

Project QUESS - Quantum Experiments at Space Scale

In August 2016, China launched a satellite named Micius named after the ancient philosopher. Its aim was to create quantum entanglement and observe its working through long distances. 

Earlier last month, the satellite sent a stream of pairs of entangled photons to two observatories around 1200 kilometers apart. The stream was sent so that there can be a direct communication link between the two observatories. This kind of communication is done by manipulating the polarisation of one in order to signal the other. 

Traditional communication involves radio waves from satellites. However through this method, there is no link to the satellite. The satellite merely serves as a method to create the entangled photons. The communication happens directly from one location to the other. This also implies that the signal will be untraceable by current methods. It is the most secure type of communication so far, since the communication cannot be intercepted while travelling from  point to point. 

However, the beams of photons could only be detected at night. The sun’s light would have drowned out the beams before it could be detected, even if the experiment was successful. To counter this problem, Jian Wei Pan, the head of the Chinese National Space Science Center plans to launch many more satellites over the next five years. The satellites will send more concentrated beams so that the detection process becomes easier and efficient.

NASA has drawn up plans to rival the chinese in this field by using the International Space Station’s laser system to relay quantum information between two areas. It is known as the National Space Quantum Laboratory program. Dr. Earl of Qubitekk says that Beijing seems to be much further ahead in the quantum race. However he cannot be sure as the progress is confidential and thus cannot evaluate the country’s progress.

Many experts also say that this is the basis for a high speed quantum internet. A network of satellites could one day connect millions of computers that may also be working based on quantum computing principles. 

The Quantum Race and competition

The launch of Micius though being significant, it also has political and military implications that are very hard to ignore. Any country could theoretically trust Micius to provide entangled photons to secure its communications. It is a strategic resource that other countries are likely to replicate. All countries would now try to reach the standards set by this experiment. This creates competition which is both good and bad for progress. One way, the countries are encouraged by each other to lurch forward, while another way, countries might try to impede on another’s progress through malicious methods. 

Conclusion

Micius has proven that we are only in the beginning of an era of fast, secure and efficient communication. Dr. Pan’s paper says that the future of the internet will be based on quantum principles.

Citations

https://www.youtube.com/watch?v=Z34ugMy1QaA

https://www.youtube.com/watch?v=ViI0OOY9oHE

https://www.olympus-lifescience.com/en/microscope-resource/primer/lightandcolor/polarization/

https://theconversation.com/chinas-quantum-satellite-enables-first-totally-secure-long-range-messages-140803

https://www.downtoearth.org.in/news/science-technology/china-s-quantum-satellite-enables-first-totally-secure-long-range-messages-71831