Generating quantum entangled photons

Abstract: In this project a laser setup was constructed, quantum entangled photons were generated and two different methods were used to show said entanglement. The entangled photons were generated through a process called spontaneous parametric down conversion (SPDC). The process includes pumping a non-linear crystal with photons, such that an incoming photon is converted into a pair of photons. A quantum mechanical model was developed which predicted polarization entanglement of two photons through correlation or anti-correlation depending on the choice of basis. The first of the two methods involved directly measuring the state of both photons and consequently confirming entanglement. The second method involved directly measuring one of the photons while the second entered a quantum eraser which consequently led to an interference pattern verifying entanglement. Several improvements were made during the course of the project, all aimed to increase the contrast ratio, a rate of quantum entanglement. The contrast was improved by increasing indistinguishability between the generated photons. At the end of the project a contrast ratio of 78 % was achieved.