Huang Chuanxin, Wang Chenxi, Zhang Hongxuan, Hu Hongyuan, Wang Zuqing, Mao Zhichao, Li Shijiao, Hou Panyu, Wu Yukai, Zhou Zichao, Duan Luming
Center for Quantum Information, Institute for Interdisciplinary Information Sciences, <a href="https://ror.org/03cve4549">Tsinghua University</a>, Beijing 100084, People's Republic of China.
HYQ Co., Ltd., Beijing 100176, People's Republic of China.
Phys Rev Lett. 2024 Sep 13;133(11):113204. doi: 10.1103/PhysRevLett.133.113204.
We report the electromagnetically induced transparency (EIT) cooling of ^{137}Ba^{+} ions with a nuclear spin of I=3/2, which are a good candidate of qubits for future large-scale trapped-ion quantum computing. EIT cooling of atoms or ions with a complex ground-state level structure is challenging due to the lack of an isolated Λ system, as the population can escape from the Λ system to reduce the cooling efficiency. We overcome this issue by leveraging an EIT pumping laser to repopulate the cooling subspace, ensuring continuous and effective EIT cooling. We cool the two radial modes of a single ^{137}Ba^{+} ion to average motional occupations of 0.08(5) and 0.15(7), respectively. Using the same laser parameters, we also cool all the ten radial modes of a five-ion chain to near their ground states. Our approach can be adapted to atomic species possessing similar level structures. It allows engineering of the EIT Fano-like spectrum, which can be useful for simultaneous cooling of modes across a wide frequency range, aiding in large-scale trapped-ion quantum information processing.
我们报告了对具有核自旋(I = 3/2)的(^{137}Ba^{+})离子进行电磁诱导透明（EIT）冷却的情况，这些离子是未来大规模囚禁离子量子计算中量子比特的良好候选者。由于缺乏孤立的(\Lambda)系统，对具有复杂基态能级结构的原子或离子进行EIT冷却是具有挑战性的，因为粒子数可以从(\Lambda)系统中逸出，从而降低冷却效率。我们通过利用EIT泵浦激光重新填充冷却子空间来克服这个问题，确保连续有效的EIT冷却。我们将单个(^{137}Ba^{+})离子的两个径向模式冷却到平均运动占据数分别为(0.08(5))和(0.15(7))。使用相同的激光参数，我们还将五离子链的所有十个径向模式冷却到接近其基态。我们的方法可以适用于具有类似能级结构的原子种类。它允许设计EIT类法诺光谱，这对于在宽频率范围内同时冷却模式可能是有用的，有助于大规模囚禁离子量子信息处理。
