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Optical control and quantum information processing with ultracold alkaline-earth-like atoms.

机译:利用超冷的碱土类原子进行光学控制和量子信息处理。

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摘要

Ultracold neutral atoms in optical lattices are rich systems for the investigation of many-body physics as well as for the implementation of quantum information processing. While traditionally alkali atoms were used for this research, in recent years alkaline-earth-like atoms have attracted considerable interest. This is due to their more complex but tractable internal structure and easily accessible transitions. Furthermore, alkaline-earth-like atoms have extremely narrow 1S → 3P intercombination transitions, which lend themselves for the implementation of next generation atomic clocks.;In this dissertation, I show that exquisite control of alkaline-earth-like atoms can be reached with optical methods, and elucidate ways to use this controllability to further different aspects of research, mainly quantum information processing. Additionally, the control of alkaline-earth-like atoms is very interesting in many-body physics and the improvement of atomic clocks.;Since heating usually degrades the performance of quantum gates, recooling of qubits is a necessity for the implementation of large scale quantum computers. Laser cooling has advantages over the usually used sympathetic cooling, given that it requires no additional atoms, which have to be controlled separately. However, for qubits stored in hyperfine states, as usually done in alkali atoms, laser cooling leads to optical pumping and therefore to loss of coherence. On the other hand, in the ground state, the nuclear spin of alkaline-earth-like atoms is decoupled from the electronic degrees of freedom. As I show in this dissertation, this allows for the storage of quantum information in the nuclear spin and laser cooling on the electronic degrees of freedom. The recooling protocol suggested here consists of two steps: resolved sideband cooling on the extremely narrow 1S0 → 3P 0 clock transition and subsequent quenching on the much shorter lived 1P1 state. A magnetic field is used to overcome the hyperfine interaction in this excited state and thus ensures decoupling of the nuclear spin degrees of freedom during the quenching. The application of this magnetic field also allows for photon scattering on the 1P1, while preserving the nuclear spin, e. g. for electronic qubit detection.;The manipulation of the scattering properties of neutral atoms is an important aspect of quantum control. In contrast to alkali atoms, whose broad linewidths cause large losses, this can be done with purely optical methods via the implementation of an optical Feshbach resonance for alkaline-earth-like atoms. Here, the scattering length resulting from the application of an optical Feshbach resonance on the 1S0 → 3P1 intercombination line, including hyperfine interaction and rotation is calculated for 171Yb. Due to their different parities, the p-wave scattering length can be controlled independently from the s-wave scattering length, thus allowing for unprecedented control over the scattering properties of neutral atoms. Furthermore, I also show how optical Feshbach resonances in alkaline-earth-like atoms can be used together with the underlying quantum symmetry to implement collisional gates between nuclear-spin qubits over comparatively long ranges.
机译:光学晶格中的超冷中性原子是用于研究多体物理学以及实施量子信息处理的丰富系统。尽管传统上使用碱金属原子进行这项研究,但近年来,类似碱土金属的原子引起了极大的兴趣。这是由于它们更复杂但易于处理的内部结构以及易于访问的过渡。此外,碱土类原子具有极窄的1S→3P互变跃迁,这为实现下一代原子钟提供了有利条件。在本论文中,我证明了对碱土类原子的精确控制是可以实现的。光学方法,并阐明了使用这种可控性来进一步研究不同方面(主要是量子信息处理)的方法。此外,在多体物理学中以及对原子钟的改进中,对碱土样原子的控制非常有趣。;由于加热通常会降低量子门的性能,因此对量子位进行重新冷却是实现大规模量子的必要条件电脑。激光冷却比通常使用的同情冷却具有优势,因为它不需要额外的原子,这些原子必须单独控制。但是,对于以超精细状态存储的量子位(通常在碱原子中进行的存储),激光冷却会导致光泵浦,从而导致相干性损失。另一方面,在基态下,碱土样原子的核自旋与电子自由度解耦。正如我在本论文中所展示的,这允许在核自旋中存储量子信息,并在电子自由度上进行激光冷却。此处建议的重新冷却协议包括两个步骤:在极窄的1S0→3P 0时钟转换上解决边带冷却,以及随后在寿命短得多的1P1状态下淬火。磁场用于克服这种激发态下的超精细相互作用,从而确保淬灭过程中核自旋自由度的去耦。该磁场的施加还允许在1P1上进行光子散射,同时保留核自旋,例如。 G。用于电子量子位检测。中性原子散射特性的操纵是量子控制的重要方面。与碱金属的线宽较宽会导致较大的损失相比,这可以通过对碱土类原子实施光学Feshbach共振,使用纯光学方法完成。在这里,对于171Yb,计算了在1S0→3P1组合线上应用光学Feshbach共振所产生的散射长度,包括超精细相互作用和旋转。由于它们的奇偶性不同,可以独立于s波散射长度来控制p波散射长度,从而可以对中性原子的散射特性进行前所未有的控制。此外,我还展示了如何将碱土类原子中的光学Feshbach共振与潜在的量子对称性一起用于在相对较长的范围内实现核自旋量子位之间的碰撞门。

著录项

  • 作者

    Reichenbach, Iris.;

  • 作者单位

    The University of New Mexico.;

  • 授予单位 The University of New Mexico.;
  • 学科 Physics Atomic.;Physics Theory.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 171 p.
  • 总页数 171
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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