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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Slow and stopped light by light-matter coherence control

Tidström, Jonas January 2009 (has links)
In this thesis we study light-matter coherence phenomena related to the interaction of a coherent laser field and the so-called Λ-system, a three-level quantum system (e.g., an atom). We observe electromagnetically induced transparency (EIT), slow and stored light in hot rubidium vapor. For example, a 6 μs Gaussian pulse propagate at a velocity of ~1 km/s (to be compared with the normal velocity of 300 000 km/s). Dynamic changes of the control parameter allows us to slow down a pulse to a complete stop, store it for ~100 μs, and then release it. During the storage time, and also during the release process, some properties of the light pulse can be changed, e.g., frequency chirping of the pulse is obtained by means of Zeeman shifting the energy levels of the Λ-system. If, bichromatic continuous light fields are applied we observe overtone generation in the beating signal, and a narrow `dip' in overtone generation efficiency on two-photon resonance, narrower than the `coherent population trapping' transparency. The observed light-matter coherence phenomena are explained theoretically from first principles, using the Lindblad master equation, in conjunction with the Maxwell's equations. Furthermore, we analyze an optical delay-line based on EIT and show that there is in principle (besides decoherence) no fundamental limitation, but the usefulness today is scant. The combination of EIT and a photonic crystal cavity is inquired into, and we show that the quality value of a small resonator (area of 2.5λ×2.5λ with a missing central rod) can be enhanced by a factor of 500 due to the increased modal density close to two-photon resonance. Open system effects (decoherence effects) are thoroughly investigated using a coherence vector formalism, furthermore, a vector form of the Lindblad equation is derived. Specifically we find an open system channel that lead to slow light and gain. / QC 20100812
2

Perforated Hollow Core Waveguides for Alkali Vapor-cells and Slow Light Devices

Giraud Carrier, Matthieu C 01 February 2016 (has links) (PDF)
The focus of this work is the integration of alkali vapor atomic vapor cells into common silicon wafer microfabrication processes. Such integrated platforms enable the study of quantum coherence effects such as electromagnetically induced transparency, which can in turn be used to demonstrate slow light. Slow and stopped light devices have applications in the optical communications and quantum computing fields. This project uses hollow core anti-resonant reflecting optical waveguides (ARROWs) to build such slow light devices. An explanation of light-matter interactions and the physics of slow light is first provided, as well as a detailed overview of the fabrication process. Following the discovery of a vapor transport issue, a custom capillary-based testing platform is developed to quantify the effect of confinement, temperature, and wall coatings on rubidium transport. A mathematical model is derived from the experimental results and predicts long transport times. A new design methodology is presented that addresses the transport problem by increasing the number of rubidium entry points. This design also improves chip durability and decreases environmental susceptibility through the use of a single copper reservoir and buried channel waveguides (BCWs). New chips are successfully fabricated, loaded, and monitored for rubidium spectra. Absorption is observed in several chips and absorption peaks depths in excess of 10% are reported. The chip lifetime remains comparable to previous designs. This new design can be expanded to a multi-core platform suitable for slow and stopped light experimentation.
3

Slow and Stopped Light with Many Atoms, the Anisotropic Rabi Model and Photon Counting Experiment on a Dissipative Optical Lattice

Thurtell, Tyler 10 August 2018 (has links)
No description available.

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