THE CHINESE ARE TAKING A BIG LEAP: Final thoughts

As we continue what we started on Monday, perhaps this will be the final one. Having explained terms like the uncertainty principle yesterday and quantum entanglement. Today let’s deal with communication itself.

Most human technology is built around the classical physics that Isaac Newton and his inheritors came up with (equal and opposite reactions, that sort of thing). When engineers hit on electricity, they perceived it in aggregate as a kind of a force; it’s either on, or it’s off. This understanding led to electric switches, which became transistors, and when you put all those transistors in a box and start turning them off and on with instructions encoded “11010001101”… it’s a computer. The computer I used in typing this piece is nothing more than a box of electric switches, being switched on and off, the switching is controlled by what we now call software’s not human hands. However, these switches are just like to say electron flow as ON; and no electron flow as OFF. This is what we call our 1s and 0s.

It is the same thing happening on your phone. When you speak, your voice is converted into analogue electrical flow (continues electric force) and then converted into digital signals which is just the ON and OFF sort of things. So each time an electron flows, it is an ON when it is switched off, it is an OFF.

But things get twisted when you are dealing with quantum particles. A quantum particle can exist in at least four different states and so each state represents something like 4 bits 0000 or 1111 etc. So they have higher capacities in carrying information than electron flow. This is the basis of quantum computers (Note, this is different from quantum entanglement that gave rise to quantum teleportation, which was explained yesterday)

Scientists have done experiments with quantum teleportation already. They have instantaneously exchanged information about the quantum states of photons, which are particles of light, transmitted 143 km between two of the Canary Islands.

But testing quantum teleportation at extremely long distances requires going to space. It’s the easiest way to set up laser communication between two distant points on the earth’s surface. That’s what the Chinese satellite, developed in cooperation with the Austrian Academy of Science, intends to do.

The satellite contains a machine that generates entangled pairs of photons by shooting a laser beam through a specially designed crystal. Each entangled pair will be split up and beamed down to stations on Earth approximately 1,200 km apart. If all goes as planned, researchers at those stations will share access to an entangled system. Any measurement on one of those photons will be instantaneously reflected in its opposite number at the other station.

The key is to  get an encryption KEY

Besides demonstrating a super-long entanglement, the scientists working with the satellite want to test new communications technology. It’s important to realize that we can’t send information like “Hey, how are you?” through quantum teleportation, much less teleport actual things. But smart thinkers realized that being able to share basic information about the state of atomic particles across distance could create a powerful encryption tool.

 “It’s very secure from the point of view that if your eavesdropper wants to listen in, usually they are within space and time.” This is where the unbreakable code comes in. Perhaps the most powerful method of encryption is the “one-time pad,” where messages are encoded using a private key known to both parties; theoretically, if the key is random, is as long as the message, is never reused, and is kept completely secret, it cannot be broken. Which sounds really good, code-wise, but it has long been impractical to ensure that two parties can always access a key that meets those standards.

Quantum entanglement could help. If people on two ground stations share access to a large enough set of entangled photons, beamed to them from a satellite in space, they can generate a sufficiently long, random key by teleporting quantum information between the entangled particles.

Nobody would be able to detect the transmission of the key. It’s very secure from the point of view that if your eavesdropper wants to listen in, usually they are within space and time; he has no access to the keys as they are actually not transmitted within space time. He lives in a different world and the keys exist in an entirely new world.

The data is not transmitted through space-time; it goes underneath purely as a mathematical subspace.

Once the people in the two stations have created a key, using their entangled particles, they can use it to encrypt a message. This can be sent by whatever method they want.

Quantum supremacy

The field of quantum information is still in its infancy. As we continue to learn the fundamentals of how quantum phenomena work at a large scale, the data collected will help physicists understand “the process that takes you from the quantum richness of the universe to the classical world we see around us,” Michalakis says.