We have all seen science fiction movies and wondered if teleportation is possible in reality. Turns out, it actually is! But don’t get your hopes too high, it’s not like the movies. We can’t teleport people instantaneously from one place to another, you still need to pass your apparation test for that. But what we can manage to do is transfer information from one place to another using Quantum Entanglement.
What’s Quantum entanglement now! Remember when you looked at your best friends face and laughed hysterically for the same reason out of nowhere, while others wondered if you have gone mad? A friendship where, let’s say, two friends complement each other, or finish each other’s sentences. This is something like that, here we have two particles doing the same. Let’s look at their friendship first.
Remember learning complementary angles in school? There are two angles (say) A and B when you add them you must get 90 degrees. So, if A is 40, B must be 50. So, when you change A to 35, B becomes 55 and so on. Similarly, here, we have these particles doing the same thing. If you change the spin of one of them, the other one changes automatically to complement it. This happens even if the two particles are really far apart. (We are talking about different planets here!) And here’s the best part, this happens faster than the speed of light!
So, all we have to do is make our “Message” interact with A. This interaction changes particle A in a unique way, in turn changing particle B. But there is one tiny problem, we cannot find out the “Message” from particle B unless we know this new state of particle A. So even though the information transfer was instantaneous, we have to wait for that phone call about the new state of A. In other words, we cannot utilize the speed of this telepathic change of entangled particles to actually transport information! But once we know the state of A, we can slightly tweak B to get our desired “Message”.
Let’s say Alice has the particle A and Bob has B. These two people are exchanging information without any trail! There is a phone call, but it is very brief, and completely useless for anyone other than Bob (or anyone who stole the particle from him). This is amazing for cryptography. There is no way that a third person, Clara, can get the desired message. (Let’s just forget the scenario where she has a gun pointed at Bob!)
Also, the “Message” which was given to Alice is destroyed. It means that, at any given point of time there was not more than one copy of the message. So, forget Clara, even Alice can’t peep into the desired message without getting caught!
Unfortunately, we know that life isn’t full of unicorns and rainbows, like everything else, even this has its fair share of shortcomings. We have already discussed how we cannot completely utilise the speed (Let’s just say Light wins for now!). We also saw how Alice and Bob need to meet before this information transfer to share the entangled pair of particles (So, this isn’t practical for random strangers!). It is a little difficult for us to create the entangled pair which can be stored separately for more than a brief period of time.
But hey, it’s possible!!