Following up on my introduction to the concept of quantum superposition, I decided to explain quantum entanglement to my future 6th grader by using two younger siblings as electrons. My inspiration came from the way they like to play together under a bedsheet, which prohibits direct observation. Disregard for a moment that we know what they are doing by the shape of the bedsheet, the sounds they are making, as well as their conversation.
By placing the two younger sibling-electrons under a single bedsheet, they interact and become entangled. Building on our previous lesson about superposition, we can’t know for certain what they are doing under there. We only have probabilities of their correlated states based on previous observations of them playing. But, we know that whatever one sibling-electron is doing, the other sibling-electron is doing the same thing.
We can test this experimentally. We can lift up one side of the bedsheet and observe one sibling-electron. We instantly know what the other sibling-electron is doing, and we can lift up the rest of the bedsheet to confirm that.
This experiment holds true even with two bedsheets. If we separate the sibling-electrons across our home, they would still be playing the same game at the same time. That’s not just a lesson about entanglement, they actually behave that way. Though not identical twins, their behaviors are highly-correlated.
They actually play a game that lends itself well to a lesson about quantum tunnelling, but that will be a lesson for another day.