| With the development of human society, the requirement of the transition and processing of information is becoming more and more prominent. At this time, the quantum information processing investigates fascinating issues at the foundations of computer science and quantum mechanics. Quantum computation, which is based on principle of coherent superposition and quantum entanglement, can solve certain problems that are hard for conventional classical computer and have great significant for our life. For decades, many physical schemes have been proposed, among which cavity quantum electrodynamics (QED) is thought to be a very promising physical system. The cavity QED, which can provide the control of quantum bit, have the bright prospects with the developing of nanotechnology and integrated on the chip. My work listed below focuses on the experiment of cavity QED which includes the whispering gallery mode microcavity and the single emitter, e.g. quantum dot (QD).1. Set up the experimental system of the microcavity and tapered fiberThe system includes: a) The microsphere is fabricated with the diameter ranging from 10μm to 100μm and the quality factor higher than 108. b) The fiber taper is fabricated by the hydrogen flame heating (with a waist less than 1μm) to effectively excite the modes in microsphere. c) With the coupling of the tapered fiber, we can use it to excite the Whisper-gallery (WG) modes in the microsphere, microdisk, microtoroid, and zeolite cylindrical microcavity with hexagonal cross section.Base on the fabrication and measurement platform, we have studied the coupling between the microcavity and tapered fiber, and the application of the microcavity especially for the cavity QED. In the high-Q microsphere, we have observed the ringing phenomena and successfully explained it in theory. We have demonstrated the EIT-like effect in a single microsphere which caused by the interference of two WG modes using the tuning of the tapered fiber. We also have got the low-threshold microlasing in the high-Q microsphere coated the Er:Yb phosphate glass layer. With the Hydrofluoric etching or polymer coating, we also have tuned the modes in the microcavity. It has wide applications in sensors and experiments of the cavity QED. In addition, we have developed the free space coupling with the deformed microsphere which is easily fabricated by the short CO2 pulse heating. It would be good for our research with the experiment of low temperature. In addition, we present the coupling of light into Ag nanowires from the fiber taper. Our demonstration offers an efficient method for the application of microcavity and promotes the realization of quantum information processing.2. Study of the single photon emitterTowards the application in cavity QED, single emitter such as quantum dot and NV center in diamond is more attractive. We have set up the Hanbury-Brown-Twiss system to demonstrate second-order correlation and detailed researched single photon emitting. CdSe/ZnS colloidal quantum dots generally exist as blinking phenomena which can be effectively modulated on the different material surface. It is shown to obviously suppress the blinking of CdSe/ZnS on the Au film. This method presents the potential application for high-speed single photon sources. We also have observed the single emitter through the HBT experiment when the QD or NV nanoparticle adopted on the surface of the microcavity.3. The coupling of QDs and microcavityWhen the QDs adopted on the surface of the microsphere, modulated photon emission from QDs have been observed, which is proved to reveal Purcell effect. It is just the weak coupling between the QDs and the microcavity. We moved the system into the low temperature. Now, we are researching the strong coupling in the QD-microcavity system in the cryogenic chamber. The experiment can be referred in further application of quantum dot in our system, which will be of greater use in our future implementation of quantum logic gate.
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