Dapsy Olatona

• Papua New Guinea University of Technology

In this study, the authors carried out a detailed analysis of the technologies required for successful implementation of a sustainable renewable energy household power supply in Papua New Guinea or PNG (PNG is a Pacific Island nation, North of Australia) to free the country from fossil fuel dependency. The role of renewable energy sources in the re...

This thesis reports experimental investigations of the magnetotransport properties of low dimensional systems (LDS). The devices were studied at low (mK) temperatures and under low/high magnetic fields as a probe of the quantum states of the samples. GaAs/AlGaAs zero dimensional (0-D) ballistic quantum dots of square geometry were studied using mag...

In this review we describe the results of magneto-transport studies in open quantum dots, in which electronic motion is expected to be predominantly ballistic in nature. The devices themselves are realized in different semiconductor materials, using quite distinct fabrication techniques. Electron interference is an important process in determining...

We consider the factors which limit electron wave coherence in open quantum dots, through a study of the reproducible fluctuations in their low temperature magneto-resistance. Our investigations indicate that at temperatures well below a degree Kelvin, electrons are able to propagate ballistically while maintaining phase coherence over very long ti...

We discuss the results of experimental studies of ballistic electron transport in regular (i.e. non-chaotic) quantum dots. At low temperatures, coherent interference between electrons gives rise to reproducible fluctuations in the magneto-resistance, as well as to a weak localization peak near zero field. The lineshape of the peak evolves from a Lo...

We discuss the origin of a striking transition in the weak localisation lineshape observed in the low temperature magneto-resistance of ballistic quantum dots with square geometry. As the dot openings are gradually closed, the lineshape evolves from a Lorentzian to a linear form and, within the framework of the present theory, this behaviour can on...

We show a striking transition in the line shape of the weak localization peak, observed in the low-temperature magnetoresistance of square semiconductor billiards. More specifically, as the point-contact openings to the dots are closed, the line shape is found to develop a non-Lorentzian dependence. In the smaller dot studied, this can be clearly d...

The National Pulsed Magnet Laboratory (NPML) provides access to high pulsed and steady magnetic fields, with particular emphasis on combining high fields with temperatures down to the millikelvin regime and a range of physical probes for condensed matter studies. NPML provides both short pulse (~ 10 ms) fields to 60 T and long duration (1 s) fields...