Have you ever thought about faster-than-light communication? Can you imagine a mechanism that would allow you to instantaneously exchange the information over arbitrarily large distances?
Well, this is exactly what many people were thinking about when the scientists revealed the theory behind quantum entanglement. Before you get too excited, be aware that physicists had already agreed that the quantum entanglement does not contradict Albert Einstein’s theory of relativity and yes, it basically means that the faster-than-light (FTL) communication is not possible. However, the entanglement phenomenon is still having a great potential to be a technological breakthrough in telecommunication. Why? We will get to that soon, but first let's try to explain to ourselves what the quantum entanglement really is.
The theory says that each fundamental particle has a property called “spin”. This property can be measured once we choose the direction in which to measure it. Such measurement can only have one of the two outcomes, either “up” or “down”.
Now imagine you have a pair of entangled particles. Assuming you are a very generous person, you will give one particle to Alice and the other one to Bob. In order to show Alice and Bob how special their new entangled particles are you will ask them to measure a spin of the particle. This is where the magic happens. Let’s say that the outcome of the Bob’s measurement was “up”. At this point, Bob already knows that the outcome of the same measurement of the Alice particle must be “down”. This correlation is what Einstein referred to as “spooky action at a distance”. It really is spooky, because experiments proved that it works and yet scientists have no idea how. This is all great, but how Alice knows what the spin of her particle is? She could also do a series of measurements, but neither Bob nor Alice would see the correlation unless they tell each other the outcomes of their measurements and compare. They can only do that by means of some known communication which by definition is no faster than light. The key thing to remember is that we are not transmitting any information during the process of measurement. The state of the other particle is the information that we deduce from the outcome of our measurement and we get that information at the moment we obtain the results which are random.
If you need to get your head around the quantum entanglement a bit more, I recommend you watch the video below.
Well, this is exactly what many people were thinking about when the scientists revealed the theory behind quantum entanglement. Before you get too excited, be aware that physicists had already agreed that the quantum entanglement does not contradict Albert Einstein’s theory of relativity and yes, it basically means that the faster-than-light (FTL) communication is not possible. However, the entanglement phenomenon is still having a great potential to be a technological breakthrough in telecommunication. Why? We will get to that soon, but first let's try to explain to ourselves what the quantum entanglement really is.
The theory says that each fundamental particle has a property called “spin”. This property can be measured once we choose the direction in which to measure it. Such measurement can only have one of the two outcomes, either “up” or “down”.
Now imagine you have a pair of entangled particles. Assuming you are a very generous person, you will give one particle to Alice and the other one to Bob. In order to show Alice and Bob how special their new entangled particles are you will ask them to measure a spin of the particle. This is where the magic happens. Let’s say that the outcome of the Bob’s measurement was “up”. At this point, Bob already knows that the outcome of the same measurement of the Alice particle must be “down”. This correlation is what Einstein referred to as “spooky action at a distance”. It really is spooky, because experiments proved that it works and yet scientists have no idea how. This is all great, but how Alice knows what the spin of her particle is? She could also do a series of measurements, but neither Bob nor Alice would see the correlation unless they tell each other the outcomes of their measurements and compare. They can only do that by means of some known communication which by definition is no faster than light. The key thing to remember is that we are not transmitting any information during the process of measurement. The state of the other particle is the information that we deduce from the outcome of our measurement and we get that information at the moment we obtain the results which are random.
If you need to get your head around the quantum entanglement a bit more, I recommend you watch the video below.
We now have the idea what the quantum entanglement is all about and why it does not allow for FTL communication. It does, however, allow for a hack-proof communication, which, if successful, could be the next big thing in IT.
Quantum cryptography is a science which focuses on exploiting quantum mechanical properties that can be used to encode information. The best known example of quantum cryptography is quantum key distribution (QKD) and the first protocol was invented in 1984 by Charles H. Bennett and Gilles Brassard (since the name BB84).
As with all scientific discoveries, we had to wait for a couple of years, but thanks to the technological advances QKD systems are now becoming a reality.
Quantum cryptography is a science which focuses on exploiting quantum mechanical properties that can be used to encode information. The best known example of quantum cryptography is quantum key distribution (QKD) and the first protocol was invented in 1984 by Charles H. Bennett and Gilles Brassard (since the name BB84).
As with all scientific discoveries, we had to wait for a couple of years, but thanks to the technological advances QKD systems are now becoming a reality.
On August 16, 2016, China successfully launched the world’s first quantum satellite. This satellite, officially known as QUESS and nicknamed Micius, will be responsible for transmitting uncrackable keys from space to the ground. The idea is that the satellite will orbit the Earth once every 90 minutes at an altitude of 500 km and it will beam entangled photons to two ground stations, approximately 1,200 km apart. People at two ground stations can then use the obtained set of entangled photons to generate an encryption key by teleporting quantum information between the entangled particles. The laws of quantum mechanics ensure that any attempt by a third party to intercept or measure the message can be immediately detected by the other two parties. This means that a given key can be easily classified as compromised and rejected before the actual encrypted communication begins.
“If QUESS is successful, China hopes to erect an Asian-European quantum key distribution network by 2020, and a global quantum communications network in 2030.” (https://www.rt.com/news/356086-china-quantum-communications-satellite/).
The quantum space race has only just begun. One thing scientists know for sure is that the world of quantum mechanics is still waiting to be explored.
Did you know about quantum entanglement?
“If QUESS is successful, China hopes to erect an Asian-European quantum key distribution network by 2020, and a global quantum communications network in 2030.” (https://www.rt.com/news/356086-china-quantum-communications-satellite/).
The quantum space race has only just begun. One thing scientists know for sure is that the world of quantum mechanics is still waiting to be explored.
Did you know about quantum entanglement?
Do you believe that it can truly revolutionize telecommunication?
Do you know any other promising implications of quantum entanglement?For those of you who want to learn more about different experiments concerning quantum communication I recommend you watch this talk https://www.youtube.com/watch?v=PDGqJyKgHJI by Anton Zeilinger (one of the pioneers of quantum mechanics).
Sources:
http://www.forbes.com/sites/chadorzel/2016/05/04/the-real-reasons-quantum-entanglement-doesnt-allow-faster-than-light-communication/2/#1b615b476d3f
https://en.wikipedia.org/wiki/Quantum_key_distribution
http://www.space.com/33760-china-launches-quantum-communications-satellite.html
https://www.rt.com/news/356086-china-quantum-communications-satellite/
http://www.popsci.com/chinas-quantum-satellite-could-change-cryptography-forever http://qz.com/760804/chinas-new-quantum-satellite-will-try-to-teleport-data-outside-the-bounds-of-space-and-time-and-create-an-unbreakable-code/
Comments
I knew nothing about quantum entanglement. It was not until I learned by reading this article.
Do you believe that it can truly revolutionize telecommunication?
I'm not convinced. Nowadays, you can always discover something new, so that the technology can already be as good than what is described in this article.
Do you know any other promising implications of quantum entanglement?
I do not know other promising of quantum entanglement
It will have huge implications on our technology, general understading of universe and even philosophy. Some scientists theoretize that our brains could be working the way they are due to quantum entanglement. That opens possibility of identifing human soul-like entity without violating logic or physics.
I've actually written an article about 'delayed choice double slit experiment' which shows that quantum-entanglement can transfer quantum pseudo-data not only in space but backwards in time as well. I also have written a short story lousy based on quantum phenomena. Both article and story are linked below (unfortunatly in polish ;P).
https://drive.google.com/file/d/0B8hZMGjJvqffelZEamZYVm5fS0k/view?usp=sharing
https://drive.google.com/open?id=0B8hZMGjJvqffWTZjOTlfenhfakE