With work at home in the context of the pandemic, more and more people are becoming more aware of the security risks of sending sensitive information over the Internet.
Thus, the best thing we can do right now is to make it difficult to intercept and hack messages, but we cannot make this impossible. So, we need a new type of internet: the quantum internet. In this version of the global network, data is secure, connections are private, and our worries about intercepting information are a thing of the past.
Recently, a discovery was made, published in Science Advances, which will make such a quantum internet possible, by expanding the concepts behind it using existing telecommunications infrastructure.
The current way to protect data online is to encrypt it using easy-to-solve math problems if there is a digital “key” to unlock encryption, but difficult to solve without it. However, hard does not mean impossible and, with enough time and computer power, current encryption methods can be broken.
How quantum communication works
Quantum communication, on the other hand, creates keys using individual particles of light (photons), which – according to the principles of quantum physics – cannot make an exact copy. Any attempt to copy these keys will inevitably cause detectable errors. This means that a hacker, no matter how smart he is or any kind of powerful supercomputer, cannot replicate a quantum key or read the message he encrypts.
This concept has already been demonstrated by satellites and fiber optic cables and used to send secure messages between different countries. So why don’t we already use this concept in everyday life? The problem is that it requires expensive and specialized technology, which means that it is not currently scalable.
Previous techniques of quantum communication they were like pairs of children’s walkie-talkies. You need a pair of phones for each pair of users who want to communicate securely. So, if three children want to talk to each other, they will need three pairs of phones (or six walkie-talkies) and each child must have two of them. If eight children want to talk to each other, they would need 56 walkie-talkies.
Obviously, it is not practical for someone to have a separate device for each person or site they want to communicate with on the internet. So a way has been found to securely connect each user with a single device each, more like phones than walkie-talkies.
Thus, each walkie talkie receiver acts both as a transmitter and as a receiver, to share the quantum keys that ensure secure communication. In this model, users only need a receiver, because they receive photons to generate their keys from a central transmitter.
Are we witnessing the beginning of the quantum internet?
This is possible due to another principle of quantum physics called “entanglement”. One photon cannot be copied exactly, but can be confused with another photon, so that both behave in the same way when measured, no matter how far away they are – what Albert Einstein called “frightening action at a distance”.
So when two users want to communicate, the transmitter sends them a pair of such photons – a particle for each user. Users’ devices then perform a series of measurements on these photons to create a common secret quantum key. Then they can encrypt their messages with this key and transfer them securely.
By using multiplexing, a common telecommunication technique of combining or splitting signals, these pairs of photons can be efficiently sent to several combinations of people simultaneously. You can also send multiple signals to each user so that they can be decoded simultaneously. In this way, the walkie-talkie pairs are effectively replaced with a system similar to a video call with several participants, in which you can communicate with each user privately and independently, as well as simultaneously.
So far, this concept has been tested by connecting eight users in one city. Work is now underway to improve network speed and interconnect more such networks. The collaborators have already started to use this quantum network as a test base for several interesting applications, beyond quantum communication. It is also desired to develop even better quantum networks based on this technology with trading partners in the next few years. With such innovations, we may see the beginning of the quantum internet in the next ten years.