Technology

This article is building off of the readers assumed knowledge of quantum entanglement. If you don't have that, they you'd absolutely be lost.

Here's a simple explanation of quantum entanglement:

Imagine you have four balls of playdoh and a coin. You flip the coin and let in land on the floor. Without looking at which side is up, you smash one of the balls of playdoh over the coin. You gently peal up the playdoh off the coin but are careful to not look at the face of the coin or the impression it left in the playdoh. You take another ball of playdoh and flatten it between your hands. You very gently lay the flattened playdoh over top of the coin-impression playdoh. You pinch just all the edges together. So now you a single piece of playdoh with the coin impression sealed inside. You do the steps of created a second piece of playdoh from the same coin with the same side up (again without looking at it). Lastly, you close your eyes and pick up the coin and put it back in your pocket, again without looking at it. So now you have TWO of these pieces of playdoh with the coin impression sealed inside and you don't know which coin impression (heads or tails) is in there, but you know its the same one in both. Instead of wrapping the playdoh in plastic so they don't dry out, you leave them out for a week and they become hard and crusty as playdoh does.

These two pieces of playdoh are essentially what quantum entangled photons are. They contain information (a coin impression of either heads or tails, but not both), both have the SAME information (both will be heads or both will be tails), and there is no way to know if its heads or tails without tearing open the playdoh to look.

Here's the expanded idea for using quantum entanglement for encryption:

Alice and Bob want to meet each other in secret a week from now. The problem is Bob's ex girlfriend, Mallory. She's has been stalking Bob to chase off any potential future girlfriends. To keep Mallory from finding out where they are meeting, you meet both Alice and Bob separately and give them one of the playdoh pieces you created in the first step. They agree that if its "heads" found inside they'll meet at the restaurant. If its "tails" found inside they'll meet at the park. If they learn Mallory knows where they're meeting, they'll not meet at all. One week later, Alice and Bob each open their playdoh and even though it crumbles, they can both see that the "tails" impression was inside the playdoh. They know each other is going to the park. They successfully meet at the park and Mallory learns nothing of the meeting or who Alice is.

A week later Alice and Bob want to meet again. They take a new pair of playdoh pieces with a new coin impression inside you made for them. This time however, Mallory overheard Bob talking to his friend about this system and what heads and tails mean. Mallory gets into Bobs apartment when he's out and finds the playdoh. She breaks open the playdoh and sees the "heads" impression and knows it means that the meeting will be at the restaurant. Mallory tries to put the playdoh back together, but its dried and crumbly, so its clear its been opened when she leaves. Bob returns to this apartment and finds the playdoh broken open, also sees the "heads" impression, but knows that someone else knows it too. At the meeting time Alice shows up at the restaurant, as does Mallory looking for Bob and whoever he is trying to meet. Bob doesn't show. Mallory never learns who Alice is because Bob wasn't there to meet and identify her there. Alice knows that Mallory is there somewhere because Bob didn't show and quietly leaves on her own.

So here's where the article is coming in for using regular internet fiber optics:

Alice and Bob want to meet a third time, and come to you for more playdoh impressions. Instead of each of them coming to your home to pick them up at separate times. You take each piece of playdoh (with the coin impression inside), and put them in cardboard boxes, and drop them in the mail. Alice gets her box and opens it up and finds the playdoh intact. Bob does the same. All of you thought that the playdoh was too fragile to share the same mail system, but the playdoh survived intact with its secret still safe inside!