Detection of Quantum States of Light - Gesine Anne Steudle

This thesis addresses different aspects of the detection of quantum states of light. Thereby, the focus was on two main experiments: The quantum nature of light was demonstrated measuring non-classical photon statistics. For the first time this was done with a fundamental experimental setup consisting of a quantum light source and only a single detector. The simplification of the experimental setup was achieved using a superconducting single-photon detector with a dead time much shorter than the source’s intensity auto-correlation time.
The other main experiment dealt with the implementation of different strategies for optimal discrimination of quantum states. In quantum mechanics, e.g. two non-orthogonal states cannot be discriminated without errors by one projective measurement. However, under certain conditions there are ways to discriminate such states unambiguously at the expense of allowing for inconclusive results. In this work experimental unambiguous discrimination of two mixed single-photon states was carried out for the first time. Furthermore, in a different scenario, where unambiguous discrimination is not possible, optimum maximum-confidence discrimination of two single-photon states could be implemented. The experimental results affirm fundamental properties of quantum mechanics and can be used to improve the experimental setups for detecting light states in various cases.