Experimental Research Of Optical Microcavities For Cavity QED

Quantum information is new branch of science, which has received widely concern in recent years. It combines the research quantum mechanics in basic physics and development from information technique, and this subject not only expands the classical information technique field, but also promotes the exploration of quantum mechanics. Quantum computation is one of the research fields in quantum information. Upon the basic theories of quantum mechanics, quantum computation has the ability to solve the problems which are not able or hard to compute by classical computer, and that could lead to profound influence. In order to realize quantum computation and achieve effective control of quantum state in a physical system, many schemes have been proposed. Among those schemes, the cavity quantum electrodynamics (QED) has promising prospect, since it can provide an almost ideal platform to control the quantum state, and is suitable for miniaturization and integration. Basing on that reason, this thesis targets on the physical realization of quantum computation, and performs a series of works centered on the cavity QED.Developments of modern microfabrication technology and progress in material preparation have provided both parts of what is need in cavity QED. The former brought the dielectric microcavities with small dimension, and the whispering gallery mode microcavity is of great attraction, because it keeps high quality factor and small mode volume. Meanwhile, the latter has lead to generation of quantum dots which is an artificial atom, it is controllable in fabrication and has superior character. For the purpose of constructing the system within microcavity and quantum dot to study the cavity QED effects, those two branches are investigated respectively, and by combining them, some cavity QED effects have been researched. In this article, we are going to introduce the achievements in aforementioned fields.Towards the whispering gallery mode microcavity, we have developed a set of related equipments and fabrication method to fabricate silicon chip based microdisk cavity. Furthermore, by using subsequent procedure the microtoroid cavity with unique structure can be formed. That cavity has reached high quality factor and small mode volume, which are related to strong Purcell effect. The planar optical microcavity is able to generate strong Purcell effect that brings the great support for cavity QED experiment. In another aspect, we found that many new phenomena exist in the whispering gallery mode microcavity, due to its special characters some effects which originally are very weak has been enhanced, such as Rayleigh scattering from material. As the result, we explored the scattering induced modal coupling, in microcavities and directly derived modal coupling strength by experimental way. Through the study on microcavity, the knowledge of coupling between microcavity and quantum dot has been gained.So far as the development of quantum dot, large quantities of content are worth studying. However, the luminescent process in single quantum dot is more attractive towards application in cavity QED. Therefore, we have studied the following aspects, which are the single photon emitting, luminescence decay process, some special character of quantum dot's fluorescence and the way for directly tuning photon emitting from quantum dot. The experiment results can be referred and applied in further application of quantum dot in our experiments.Within whispering gallery mode microcavity and quantum dot, we composed the coupled system which has two level energy structure and optical field. In experiment, the microcavity can directly influence quantum dots emission via Purcell effect. The modulated luminescent spectrum has been observed. In the mean time, we also realized controlled coupling between microcavity and quantum dots with the help of near field coupling device. Related experiment technology provides the conditions to achieve a controllable Purcell effect within the microcavity and single quantum dot.Our experiment works introduced in this thesis have already proved the potential of whispering gallery mode microcavity coupling with quantum dot to study the cavity QED. The superior characters of those elements guarantee that they can be applied in engineering and basic research field. More importantly, they can make advancement for study of quantum information, and are hopeful to construct solid foundation for quantum computation device.