| 研究実績の概要 |
In FY2018, the research had a major breakthrough. We have demonstrated an optical tweezer based single atom trapping on an optical nanofiber cavity. We show that fluorescence of single atoms loaded from an optical molasses and trapped on the nanofiber, can be readily observed in the real-time through the fiber guided modes. The fluorescence photon counts measured through the fiber guided modes, clearly shows discrete step-like signal with ON-times of 10-100 ms, indicating that single atoms are trapped and interfaced to the nanofiber.
We have carried out photon correlation measurements of the fluorescence signal to further clarify the atom number and the dynamics of the trap. The antibunching of the fluorescence signal, confirms that only single atoms are trapped on the nanofiber. The trap lifetime is measured to be 60 ms. These results open new possibilities for deterministic preparation of single atom events for quantum photonics applications on an all-fiber platform.
A key design principle for the success of the trapping scheme, is the choice of nanofiber diameter. From the theoretical simulations, we have found that for trapping Cs-atoms using magic-wavelength of 937 nm, a nanofiber diameter of 300 nm gives the optimum trapping condition. It enables a trapping minimum to be created within 200 nm from the fiber surface and a channeling efficiency of 10% can be realized at the trap position. Therefore, by implementing a nanofiber cavity with a central region of 300 nm diameter, has enabled the successful demonstration of the trapping scheme.
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