Phase Memory of Photons

William (Christian) Julius

2020

This experiment explores what happens to a laser beam when different polarization states of light are sent through an interferometer with a changing effectivephase retardance between vertical and horizontal polarization states. This was tested in a Mathematica simulation and then in the lab with three different types of birefringent crystals: A zero-order, a multi-order, and a beta bariumborate (BBO) crystal. After investigating the effects of the first two crystals, the BBO crystal was tested and the results were inconclusive. Data was taken by rotating the BBO crystal and recording the intensity at every 0.5° rotation. The calibration data was either at a peak or a trough which agreed with our theory. This was modeled in a Mathematica notebook. During the second run with an incoming polarization state of 45°, we attempted to match the calibration data by recording the intensity at every 0.5°. From this we were able to see an intensity difference, but no shift in peaks relative to the horizontally polarized case. We took another data set with an incoming polarization state of 45° but measured the intensity at every 0.33° rotation of the BBO crystal and we were able to see a shift in peaks relative to the horizontally polarized case. Even though there is a shift in peaks between the two tested cases, the results of the experiment were inconclusive because there is not enough evidence to claim that there is a phase shift that is consistent with our predictions.