Ivory M, Nordquist C D, Young K, Hogle C W, Clark S M, Revelle M C
Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Rev Sci Instrum. 2024 Sep 1;95(9). doi: 10.1063/5.0204413.
Quantum processors and atomic clocks based on trapped ions often utilize an ion's hyperfine transition as the qubit state or frequency reference, respectively. These states are a good choice because they are insensitive in first order to magnetic field fluctuations, leading to long coherence times and stable frequency splittings. In trapped ions, however, these states are still subject to the second order AC Zeeman effect due to the necessary presence of an oscillating magnetic field used to confine the ions in a Paul trap configuration. Here, we measure the frequency shift of the 2S1/2 hyperfine transition of a 171Yb+ ion caused by the radio frequency (RF) electromagnetic field used to create confinement in several microfabricated surface trap designs. By comparing different trap designs, we show that two key design modifications significantly reduce the AC Zeeman effect experienced by the ion: (1) an RF ground layer routed directly below the entire RF electrode, and (2) a symmetric RF electrode. Both of these changes lead to better cancellation of the AC magnetic field and, thus, overall reduced frequency shifts due to the AC Zeeman effect and reduced variation across the device. These improvements enable a more homogeneous environment for quantum computing and can reduce errors for precision applications such as atomic clocks.
基于囚禁离子的量子处理器和原子钟通常分别利用离子的超精细跃迁作为量子比特状态或频率参考。这些状态是很好的选择，因为它们一阶对磁场波动不敏感，从而导致长的相干时间和稳定的频率分裂。然而，在囚禁离子中，由于用于在保罗阱配置中囚禁离子的振荡磁场的必然存在，这些状态仍会受到二阶交流塞曼效应的影响。在这里，我们测量了在几种微纳加工表面阱设计中，用于产生囚禁的射频（RF）电磁场导致的171Yb+离子2S1/2超精细跃迁的频移。通过比较不同的阱设计，我们表明两个关键的设计改进显著降低了离子所经历的交流塞曼效应：（1）一个直接路由到整个射频电极下方的射频接地层，以及（2）一个对称的射频电极。这两个变化都导致更好地抵消交流磁场，因此，由于交流塞曼效应导致的整体频移减小，并且整个器件上的变化也减小。这些改进为量子计算提供了更均匀的环境，并且可以减少诸如原子钟等精密应用中的误差。
