Scalable Quantum Computing with an Ion Crystal Stabilized by Tweezers and Sympathetic Cooling
| Autor: | Yu-Ching Shen, 沈于晴 |
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| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 Scalability of quantum computing based on trapped ions in a linear radio-frequency trap has been a challenge due to instability of crystallization and heating. To construct a large-scale ion array with single qubit addressability, the ions’ spacing must be kept a few times larger than or at least comparable to the beam size, which is of the order of microns. This implies that the longitudinal confinement vanishes as the number of ions gets very large. Meanwhile, the collective motional modes of very low frequencies are easily thermally populated and hard to be cooled. We thus propose a scalable scheme combining the applications of optical tweezers and sympathetic cooling. We demonstrate that for a large-scale ion chain, the application of optical tweezers raises the lowest longitudinal frequency by effectively pinning the ions in space. We calculate the steady-state profile of ions’ position fluctuations given that the system exposes to heat and is also sympathetically cooled at the same time. We find that the optical tweezers can enhance the stability of the longitudinal arrangement. Also, it blocks heat propagation of the transverse motion, suggesting that the qubit gate operation based on transverse modes can be done in parallel and thus protected by optical tweezers. This allows us to deal with only a portion defined by two edge ions that are illuminated by tweezer beams. This segment of the ion array is confined by a “local trap” provided by two effectively pinned ions. We demonstrate the relevant cooling efficiency and discuss the relaxation dynamics. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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