<p>This dissertation presents the first experiments on radio frequency (rf) spectroscopy of a quasi-two dimensional strongly interacting ultracold atomic Fermi gas. A 50-50 mixture of spin-up and spin-down atoms is confined in a series of pancake-shaped traps produced using an optical standing-wave. To make the system quasi-two dimensional, I adjust the Fermi energy in the weakly confined direction to be comparable to the harmonic oscillator energy level spacing in the tightly confined direction.</p><p>For a perfectly two dimensional system, at low enough temperature, spin-up and spin-down atoms should form dimers in the ground state of the tightly confined direction. However, in our quasi-two dimensional system I find that the simple dimer theory does not agree with the measured radio-frequency spectra. Instead, the data can be explained by polaron to polaron transitions, which is a many-body effect. Here, a polaron is a spin-down impurity surrounded by a cloud of particle-hole pairs in a spin-up Fermi sea. With this unique strongly interacting quasi-two dimensional system, I am able to study the interplay between confinement induced two-body pairing and many-body physics in confined mesoscopic systems of several hundred atoms, which has not been previously explored and offers new challenges for predictions.</p> / Dissertation

Optical reflectance of the quasi two dimensional compound Hg₂.₈₆AsF₆ has been investigated in the optical range, 0.5 to 4 eV. The spectra clearly show a plasma edge at 3 eV. They are fitted to a Drude model and two Lorentz oscillators. From the plasma frequency and the model parameters values for the dc conductivity and the effective mass and an estimate of the crytsal anisotropy have been obtained. The results compare well with earlier electrical measurements on this compound. / Thesis / Master of Science (MSc)

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20088号 / 工博第4255号 / 新制||工||1659(附属図書館) / 33204 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 中村 裕之, 教授 酒井 明, 教授 吉村 一良 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM