This experiment describes some of the failures of classical physics. Details of this experiment can be found in many sources, and it is interesting to work out the explanation and discover some of the joys of Quantum mechanics. The basic apparatus consists of a polarizer. When light is passed through the polarizer, it allows some part of the light to pass through. A physical way to think of this is to imagine that the polarizer is a measurement device. For example an X polarizer measures how much of the light is polarized along the X-direction. Consider a beam of light travelling along the X direction. (a) The beam is passed through a Z polarizer followed by a Y polarizer. Experi- mentally the observed result is 0. Or in other words, none of the light passes through. Does this make sense classically ? Explain why or why not. (b) Now consider the experiment where the original beam is passed first through a Z polarizer followed by a polarizer at 45 degrees to the Z polarizer and perpendicular to the X direction. The experiment observation is that 25% of the initial light is detected after passing through both the filters. Does it make sense classically ? (c) Now consider the experiment in which the original beam of light is passed through the two polarizers above and then through a Y polarizer. The result is that 25 % of the initial light passes through once again. Explain the contradiction between the first experiment and this experiment in classical physics. We have already given the quantum mechanical description of this experiment in terms of measurement of the polarization of light. In order to explain the results, we shall start with some basic ideas. A beam of light polarized along the Z direction is denoted by |Z > and that along the Y direction is |Y >. A beam of light in the YZ plane at an arbitrary angle θ to the Z direction can be thought of as the ket |I > which is given by |I >= |Z > cosθ + |Y > sinθ Each time the light passes through a polarizer, one of the directions is picked. This can be thought of in terms of the projection operator of the correspond- ing polarized state. Now, explain each of the experiments above by performing quantum mechanical calculations. Can u solve it?????????