|Ψ>=a|0>+b|1>

U(|Ψ>|0>)=|Ψ>|Ψ>=(a|0>+b|1>)(a|0>+b|1>)=aa|0>|0>+ab|0>|1>+ba|1>|0>+bb|1>|1>)

U(|Ψ>|0>)=U(a|0>|0>+b|1>|0>)=aU(|0>|0>+bU(|1>|0>)=a|0>|0>+b|1>|1>

One day an English fighter pilot was shot down over Germany. When the pilot was captured by the enemy soldiers, his leg was wounded and they had to amputate it.

The pilot asked, "Could you please drop my leg over my base in England." Even though this was an odd request, they did it. A while later, his other leg was injured and had to be cut off too. Once again he asked for them to drop his leg over his base in England, and again they did it. Later on, his arm was wounded and it had to be removed.

Again he asked for them to drop it off over his base in England, but this time they wouldn't do it. He asked them why they wouldn't and they said, "Ve dink you're trying to escape."