Superposition principle — in layman’s terms

While Schrödinger’s cat illustrates superposition, it may trigger some simple questions

The following game will show how we can increase the odds of winning from 50% with a regular fair coin to 100% with a “quantum coin” by

Regular coin game.

Lets first do the game with a regular fair coin.

It is obvious that our chances of winning is 50%. Also, it doesn’t really matter if we opened the box and looked inside at step 4. If we played this game, say a 1000 times, regardless of us looking at the intermediate result at step 4, the chance of winning is always 50%. Figure 1 illustrates this.

Quantum coin game.

Lets now play the game with a quantum coin in the box. The quantum coin is similar to the regular coin — meaning it can be in two states, head or tail, and there is a 50% chance of it being in either of these states after an operation equivalent to shaking the box.

We can repeat this game any number of times, and so long we cheat each time and our opponent doesn’t notice, we can win. Lets say, opponent notices that we are always looking at the quantum coin before the first coin toss.

So even though the opponent knows our looking into the quantum box before first shake has something to do with winning, it will not make sense how that can enable us to win, because opening the box after first shake showed the quantum coin behaved exactly like a fair coin.

We can now let in the opponent on our secret. We can confess even we don’t understand it too from a common sense perspective, except the following strategy always works

So to summarize the strangeness of the quantum coin toss

The mathematical explanation (without equations) for how two of the four branches disappear is quite simple.

This explanation was created based on Scott Aaronson’s blog. There is a book that is largely based on his blog Quantum Computing since Democritus: Scott Aaronson: Amazon.com: Books

For more details on what kind of “shaking operation” is performed on quantum coin etc, notes at the end of the answer to a related question may help How have physicists developed a mathematical model describing quantum phenomenon if we don’t really know what it means?

Originally published at www.quora.com.

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