Quantum Internet is a dream that has been in progress for many years; In theory, it is effective even though the use of technology to science has yet to be explained, but it’s still just a dream. In fact, we still cannot take advantage of the strange entanglement of photons and electrons to secretly send messages that only the two ends of the communication wire know.
Obviously, communication is useful in government administration and in the military, but industries that need security such as banking, business deals, or even sensitive messaging need a system. confidential communication. The need has always existed, and while trying to realize it, perhaps this question should also be added to the scientific and technical circles:
How should a global quantum internet system be built?
Part of that answer is obtained through the research efforts of Sumeet Khatri et al., The group currently working at Louisiana State University. They studied a series of ways to build the quantum internet and made a point: in order to optimize costs, you need to build a set of quantum satellites in orbit, continuously emitting photons that are already in the entanglement camp. ground. To put it simply, the infrastructure that makes up the quantum internet will be outside of the Earth.
A little background knowledge to build understanding building.
What makes any quantum communication system the entanglement element of the particle. This is a phenomenon that occurs when the existence of two quantum particles are linked, even when the distance between them is extremely large. Measuring one particle to get its value, we will immediately know the factor of that particle and immediately know the state of the other particle. Einstein called this “bizarre activities at a distance“.
The first picture of quantum entanglement.
Physicists often create “quantum entanglement” through the use of a pair of photons produced at the same time and place. When sending two photons to different locations, the entanglement element allows the two particles to be related, by rotating them we can send absolutely safe messages.
The conundrum is that the tangled state is easy to disappear. Any interaction between a photon and its surroundings can break the bonds between the two particles. That is also the reason why it is difficult for satellites to shoot particles through the atmosphere or let them run through fiber optic cables. When the photon interacts with the atom in the air or with the mirror in the cable, the turbulence element disappears. It turns out that the maximum distance from which the quantum entanglement can operate smoothly is only a few hundred kilometers.
So how do you get the global quantum internet? Consider using quantum repeater – devices that receive and measure the quantum of a photon, then transfer those quantum properties to a new photon and send it on. This process will preserve the particle’s turbulence, allowing it to continuously jump over the repeater to reach the final destination. However, this technology is only experimental, it will be many years before it will be ripe for commercialization.
Another way: create a tangled pair of photons in the Universe and send them to two earth stations. The ground stations will inherit the magnetic confusion, allowing the delivery of messages away with an extremely high level of security.
In 2017, China’s Micius satellite was tested to prove that turbulence is preserved during downward from orbit. It turns out that in this case the photon could travel much farther than expected because it would only need to travel about 20 km in the atmosphere, if the satellite flew high enough.
China’s quantum internet testing project opens up great potential.
Prof Khatri et al say that a satellite array similar to Micius would be a better way to deploy the quantum internet. The key to secure communications: two earth stations must simultaneously see the satellites, in order to both receive the downlinked photon.
How high must satellites fly? How many satellites do we need? The research team replied: “Since satellites are currently so expensive, we will need as few satellites as possible to remain operational for a long time“.
To test this idea, Khatri et al. Created a model of a quantum satellite array. They found that a number of factors have to be traded for a smooth operating system. For example, a number of satellites flying less at high altitudes will have global coverage, but the higher the satellite, the more photons will be lost.
But if the satellite flies low, the space for a satellite to move so that it can see both ground stations will be very modest. For the satellite array to fly low, we will need a larger number of satellites, pushing the cost too high.
Another question: Do we want to put 400 more satellites into orbit?
Based on these limits, Professor Khatri stated that the satellite array should have 400 aircraft and fly at an altitude of 3,000 meters. That is many times the requirement of the GPS system, when we only need 24 satellites to provide ground-based positioning services.
Even if the satellite array has 400 units, the distance between earth stations is limited to 7,500 km. That means that the distance of the two ends of the wire is limited to 7,500 km; send confidential messages to loved ones in the city. Ho Chi Minh is fine, but if your girlfriend lives in Europe, you will not be able to take advantage of quantum puppetry to transmit love letters.
However, Professor Khatri and his colleagues said that quantum internet with overhead satellites will still be more efficient than repeaters that can only be less than 200 km apart.
The quantum internet system will need a huge investment. In the current economic situation, and based on the successes Micius satellite has had, the initial assessment shows that China has the potential to become a pioneer of quantum internet technology. They have been planning to implement this new technology in practice.
Europe and America are not interested in the internet of the future. But the situation will change if the quantum internet proves itself. By then, the quantum race will be fierce.
Refer to MIT Technology Review