M.Sc Student | London Paz |
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Subject | All-Optical Reconstruction of atomic Ground-State Population |

Department | Department of Physics |

Supervisor | Professor Emeritus Amiram Ron |

Full Thesis text |

In the past decades, alkali-metal atoms have become a central ingredient in quantum optics applications, mostly due to the simplicity of their electronic internal structure. In many atom-photon phenomena and particularly in multi-photon processes, a key element is the distribution of populations among the various states within the alkali ground-level manifold. In diverse examples, driving the atoms into a specific designed and monitored quantum state is necessary. Schemes that accurately and robustly measure or estimate the quantum state are promised to be essential in research and in practical applications.

The quantum state of a physical system contains information which can be used to predict the outcome of measurements. The inverse operation, namely, the determination of an unknown quantum state by measuring a sufficient number of measurements on identically prepared copies of the system, is a subject of great interest, known as quantum state 'reconstruction', 'determination', or 'estimation'. The reconstruction of a quantum state is a nontrivial problem and the complete information could not always be achieved.

In this thesis, we study a population distribution reconstruction scheme, which is based on all-optical linear absorption measurements of weak light fields. This reconstruction scheme has several different features compared to existing protocols published so far. Those include a non-interfering interrogation, and independence from external magnetic fields. Initially, we establish the mathematical description of the scheme and realize its inherent limitations. After that, numerical tests are performed in order to validate the scheme and to estimate the level of accuracy that can be achieved in real-life experiments. We predict that the reconstructed quantities will be accurate to a few percent in a meticulous setup. Finally, we experimentally demonstrate the reconstruction scheme in two optical pumping examples. We show how a population-based analysis can be used to understand basic phenomena in quantum-optics and to verify and calibrate parameters in a theoretical numerical model. The results were recently published in Physical Review A.