Quantum Information Processing with Non-classical Light

Quantum information processing (QIP) is a field concerned with technological applications of quantum mechanical phenonomena. In many cases, photons are an ideal quantum system for such applications. Photons exhibit superb coherence properties, are robust to environmental noise, and can be transmitted over long distances. One of the main difficulties of photon based quantum information processing is the generation of non-classical light fields. Non-classical light fields exhibit counting statistics which are inconsistent with the classical theory of radiation. These nonclassical statistics are precisely what QIP applications make use of in many cases. This thesis explores the applications of non-classical light fields for quantum information processing applications. There are three main parts to this work. The first part is a theoretical analysis of quantum cryptography based on non-classical light sources. In this part, a theoretical study on sub-Poisson light sources is presented, which quantitatively characterizes their advantage over classical sources such attenuated laser. Next, the security of quantum cryptography with entangled photons is investigated. A security proof is presented, and it is shown that such protocols have significantly enhanced security properties, potentially allowing quantum cryptography over 170km with currently available technology. The second part is an experimental demonstration of quantum cryptography using sub-Poisson light from an InAs quantum dot. A fully functional system is presented, and an experimental comparison between the quantum dot source and an attenuated laser is made. It is shown that the quantum dot can withstand 5dB of additional channel loss over the attenuated laser.