Satellite System Achieves Secure Quantum Communication Over Record Distance
Researchers from Italy and Russia have succeeded in demonstrating the possibility of quantum communication at a global scale. In their experiment they exchanged information between photons that were 20 000 kilometers away from each other. Using this new form of communication in combination with the superior processing power of quantum computers we are looking at something that may only rival the discovery of electricity as far as how it will transform society.
The full capability of quantum computing is estimated to be around 1000 times more powerful than even todays most advanced supercomputers. When it comes to quantum communication you are looking at a similar multiplication of potential, albeit more so when it comes to security. Both of these rely on what is called a quantum network where a bunch of photons (light particles) are entangled by shooting them through a crystal. When they are entangled they exist in a wave-form of probability, which creates a matrix of informational complexity that far surpasses modern day electronics.
There are some misunderstandings when it comes to quantum mechanics. One of them being that whatever you do to one entangled will happen to the other. That is false and is an over-exaggeration of the correlation between each particles spin- in that after measuring one, you will always know the opposite particles spin. This is why we call it “entanglement”. Otherwise each particle exists in a waveform of probability that looks something like this.
In other words, it is a structure of probable locations that cluster around certain spaces throughout time.
This feature allows us to “sort of” observe the wave-form from further away, without necessarily turning it in to a particle. Furthermore there are tricks you can do with laserbeams/electromagnetism to program the spin correlation without collapsing the wave-form. This is how you get quantum networks, which instead of existing as a one or zero, exist as a superposition of both. In this manner, quantum calculation and communication work in the same way.
As far as communication is concerned, since you can entangle multiple photons in a chain of interlocking correlation, once you measure a photon from one part of the chain, all other photons determine their spin in relationship to that one.
This is what makes quantum communication so secure, because sender and receiver should have directly correlated photons that haven’t aligned themselves to any other observer. When they are not directly correlated, both sides will know that there has been a data breach. The same principle allows people reading a calculation from a quantum computer to know know if it’s been tampered with.
So what gives quantum technologies there speed? Well, for one- miniaturization allows more information to be encoded within a smaller surface space and two – the information is traveling faster then light. Which is important distinction because no “thing” i.e. matter, energy is going that fast, just the correlation of spin between photons.
An even more important distinction is that not every aspect of quantum technology will travel that quickly. Some aspects will be confined to the speed of light, such as “loading” entangled photons from one location to another via transference through fibre optic cables. Which is exactly what happened in this particular experiment.
Researchers from the University of Padova have now proven how to transport photons securely across continental Europe using their Global Navigation Satellite System. Findings were reported in the journal Quantum Science and Technology.
Co-lead author Dr. Giuseppe Vallone is from the University of Padova, Italy. He said: “Satellite-based technologies enable a wide range of civil, scientific and military applications like communications, navigation and timing, remote sensing, meteorology, reconnaissance, search and rescue, space exploration and astronomy
“The core of these systems is to safely transmit information and data from orbiting satellites to ground stations on Earth. Protection of these channels from a malicious adversary is therefore crucial for both military and civilian operation
Information was broadcasted from the Russian GLONASS constellation to the Space Geodesy Centre of the Italian Space Agency.
“Space quantum communications (QC) represent a promising way to guarantee unconditional security for satellite-to-ground and inter-satellite optical links, by using quantum information protocols as quantum key distribution (QKD).”
Co-lead author Professor Paolo Villoresi said: “”Our experiment used the passive retro-reflectors mounted on the satellites. By estimating the actual losses of the channel, we can evaluate the characteristics of both a dedicated quantum payload and a receiving ground station.