Generation of Single-Photon States using a Microcavity

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This research project deals with photons, the basic particles of the radiation field, and aims at establishing a technique to generate single photons. This would contribute to the understanding of the non-classical nature of photons and to give a basis of ultimate energy-conserving method of optical communications using single photons. The idea is to generate a single fluorescence photon from an atom or a molecule utilizing the "self-regulation" property of the Rabi dynamics of optically excited atoms or molecules. If this emission process occurs in a free space the emitter is coupled to a number of field modes and one cannot regulate the emission mode. Thus we locate the atom in a microcavity in order to have the emitted photon in a single mode defined by the cavity. Thus we expect to increase the capture probability of the single photon in a manner where the photon is readily utilized.For this purpose we have constructed a microcavity and examined its performance using rhodamine6G dy … More e as the emitter. The emission was analyzed using a Hanbury-Brown Twiss scheme to determine the quantum-mechanical second order coherence gィイD1(2)ィエD1. Also, theoretical investigation on the emission process in a microcavity is made.The dye molecules put into the cavity region of the planar microcavity were excited by the second harmonic of a pulsed Nd:YAG laser of pulse width 7ns with repetition frequency 10 pps. Dye concentration from 5x10ィイD1-3ィエD1 to 5x10ィイD1-5ィエD1 mol/l were tested with varying pump power and with the gate time 30ns. High density and/or high pump power resulted in a Poisson distribution of photons, while low density and/or low power resulted in Bose-Einstein distribution. For very low powers single photons were observed with their occurrence probability of the order of 1/100. Further reduction of dye concentration will be required in order to obtain a single-photon state which will result when only one molecule emits on pump pulse.Theoretical development on three dimensional analysis and investigation on two atom interference have been made. Less