A nuclear-spin exchange interaction exists between two ultracold fermionic alkali-earth (like) atoms in the electronic $^{1}{\rm S}_{0}$ state ($g$-state) and $^{3}{\rm P}_{0}$ state ($e$-state), and is an essential ingredient for the quantum simulation of Kondo effect. We study the control of this spin-exchange interaction for two atoms simultaneously confined in a quasi-one-dimensional (quasi-1D) tube, where the $g$-atom is freely moving in the axial direction while the $e$-atom is further localized by an additional axial trap and behaves as a quasi-zero-dimensional (quasi-0D) impurity. In this system, the two atoms experience effective-1D spin-exchange interactions in both even and odd partial wave channels, whose intensities can be controlled by the characteristic lengths of the confinements via the confinement-induced-resonances (CIRs). In current work, we go beyond that pure-1D approximation. We model the transverse and axial confinements by harmonic traps with finite characteristic lengths $a_\perp$ and $a_z$, respectively, and exactly solve the "quasi-1D + quasi-0D" scattering problem between these two atoms. Using the solutions we derive the effective 1D spin-exchange interaction and investigate the locations and widths of the even/odd wave CIRs for our system.
It is found that when the ratio $a_z/a_\perp$ is larger, the CIRs can be induced by weaker confinements, which are easier to be realized experimentally.
The comparison between our results and the recent experiment shows that the two experimentally observed resonance branches of the spin-exchange effect are due to an even-wave CIR and an odd-wave CIR, respectively. Our results are advantageous for the control and description of either the effective spin-exchange interaction or other types of interactions between ultracold atoms in quasi 1+0 dimensional systems.
Trapped neutral atoms have become a prominent platform for quantum science, where entanglement fidelity records have been set using highly-excited Rydberg states. However, controlled two-qubit entanglement generation has so far been limited to alkali species, leaving the exploitation of more complex electronic structures as an open frontier that could lead to improved fidelities and fundamentally different applications such as quantum-enhanced optical clocks. Here we demonstrate a novel approach utilizing the two-valence electron structure of individual alkaline-earth Rydberg atoms. We find fi…
We theoretically characterize interactions, energetics, and chemical reaction paths in ionic two-body and three-body systems of alkali-metal and alkaline-earth-metal atoms in the context of modern experiments with cold hybrid ion-atom mixtures. Using \textit{ab initio} techniques of quantum chemistry such as the coupled-cluster method, we calculate ground-state electronic properties of all diatomic $AB^+$ and most of triatomic $A_2B^+$ molecular ions consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, and Yb atoms. Different geometries and wave-function symmetries of the ground state are found fo…
We theoretically investigate the properties of highly polar diatomic molecules containing $^2S$-state transition-metal atoms. We calculate potential energy curves, permanent electric dipole moments, spectroscopic constants, and leading long-range dispersion-interaction coefficients for molecules consisting of either a Cu or Ag atom interacting with an alkali-metal (Li, Na, K, Rb, Cs, Fr) or alkaline-earth-metal (Be, Mg, Ca, Sr, Ba, Ra) atom. We use ab initio electronic structure methods, such as the coupled cluster and configuration interaction ones, with large Gaussian basis sets and small-co…
State-dependent lattices for quantum computing with alkaline-earth-metal atoms
最近碱土原子的实验进展为量子计算方案打开了大门，在该方案中，量子比特被编码在长寿命的核自旋态中，并且这些物种的亚稳态电子态被用于操纵和读出量子比特。在这里，我们将讨论这些方案的一个变体，其中门操作在核自旋相关的光晶格中进行，通过近共振耦合到亚稳态激发态形成。这提供了对先前方案的替代方案[A]。J. Daley，M. M. Boyd，J.Ye和P.Zoller，Phys.Rev.Lett 101，170504（2008）]，其涉及用于不同电子状态的独立晶格。在前面的情况下，我们展示了如何现有的想法与碱原子的量子计算，如通过受控碰撞纠缠可以从重要的技术限制。我们还提供了有关使用亚稳态的碰撞损失通过有损封锁机制执行门操作的更多详细信息。
Symmetry-protected topological phases of alkaline-earth cold fermionic atoms in one dimension
研究了自旋为I的一维碱土冷费米子原子在半填充时的保序拓扑相的存在性。在这方面，需要一些轨道自由度。它们可以通过考虑碱土原子的亚稳态激发态或光晶格的p带来引入。使用互补技术，我们表明，SU（2）Haldrons拓扑相位稳定从这些轨道自由度。在这些相位之上，我们发现了拓扑相位的出现与扩大SU（2 I +1）对称性，这只取决于核自旋自由度。后者阶段的主要物理性质进一步研究使用矩阵产品状态的方法。一方面，我们发现当I=1/2，5/2，9/2，…时，这些相是对称性保护的拓扑相，这与镱和锶冷费米子直接相关。另一方面，对于I（=半奇整数）的其他值，这些拓扑相位仅在精确SU（2 I +1）对称性的存在下才稳定。
我们演示了单个碱土原子在光镊中的单次成像和窄线冷却，特别是被困在$515.2~\text{nm}$光中的锶-88原子。我们实现高保真单原子分辨成像检测光子从宽单重态跃迁，而冷却的窄相互组合线，并将这种技术扩展到高度均匀的二维阵列的$121$镊子。成像过程中的冷却是基于以前未观察到的窄线西西弗斯机制，我们预测这将适用于各种各样的实验情况。此外，我们证明了光分辨边带冷却的单原子接近运动的基态的镊子。在成像过程中损失的精确测定表明，从$^1$ P $_1$到$^1$ D $_2$的分支比比通常引用的大两倍以上，这也是我们的从头计算预测的差异。我们还测量了在$515.2~\text{nm}$镊子中的互组合线的微分极化率，并通过将镊子极化从线性调谐到椭圆来实现魔捕配置。我们目前的计算，与我们的结果一致，预测魔术交叉线偏振在$520(2)~\text{nm}$和交叉独立的偏振在500.65（50）nm。我们的研究结果为基于镊子中单独控制的碱土原子的广泛的新实验途径铺平了道路-从原子物理学的基础实验到量子计算，模拟和计量实施。
Ultracold gases of fermionic alkaline-earth (like) atoms are hopeful candidates for the quantum simulation of many-body physics induced by magnetic impurities (e.g., the Kondo physics), because there are spin-exchange interactions (SEIs) between two atoms in the electronic ground ($^1$S$_0$) and metastable ($^3$P) state, respectively. Nevertheless, this SEI cannot be tuned via magnetic Feshbach resonance. In this work we propose three methods to control the SEI between one atom in the $^1$S$_0$ state and another atom in the $^3$P$_2$ states or $^3$P$_2$-$^3$P$_0$ dressed states, with one or tw…
