Suppose we are given two boxes and we are told that there is a ball in either one of them. We are free to pickup any one of the boxes - but only one. Then we are allowed to measure or check what is in the picked box and the other one. Normally we would have 50% chance of finding the ball in the box we picked. Is it possible to build the system in such a way that the ball always turns up in the box that was not picked up. i.e if we pickup a box we will never find the ball inside it but if we check the other box the ball would be in it. Even if we repeat the experiment, the ball should not turn up in the box that was picked but always turn up in the other one. I know this would be impossible using large objects like a ball, but if we replcae the ball with an electron which can be in a qauntum state, is this possible?