On-line Excited-State Laser Spectroscopy of Trapped Short-Lived Ra$^+$ Ions
O. O. Versolato, G. S. Giri, L. W. Wansbeek, J. E. van den Berg, D. J. van der Hoek, K. Jungmann, W. L. Kruithof, C. J. G. Onderwater, B. K. Sahoo, B. Santra, P… 展开作者
O. O. Versolato, G. S. Giri, L. W. Wansbeek, J. E. van den Berg, D. J. van der Hoek, K. Jungmann, W. L. Kruithof, C. J. G. Onderwater, B. K. Sahoo, B. Santra, P. D. Shidling, R. G. E. Timmermans, L. Willmann, H. W. Wilschut
作为一个单一的捕获Ra $^+$离子的原子宇称破坏实验的重要一步，激光光谱实验进行了与在线产生的短寿命$^{212,213,214}$ Ra $^+$离子。测量了$^{213}$ Ra $^+$中$6\,^2$ D $_{3/2}$ \，-\，$7\,^2$ P $_{1/2}$和$6\,^2$ D $_{3/2}$ \，-\，$7\,^2$ P $_{3/2}$跃迁的同位素位移和$7\,^2$ S $_{1/2}$和$6\,^2$ D $_{3/2}$态的超精细结构常数。这些值为所需的原子理论提供了基准。通过光学搁置测量亚稳态$6\,^2$ D $_{5/2}$状态的寿命的下限$232(4)$ ms。
英文摘要：
As an important step towards an atomic parity violation experiment in one single trapped Ra$^+$ ion, laser spectroscopy experiments were performed with on-line produced short-lived $^{212,213,214}$Ra$^+$ ions. The isotope shift of the $6\,^2$D$_{3/2}$\,-\,$7\,^2$P$_{1/2}$ and $6\,^2$D$_{3/2}$\,-\,$7\,^2$P$_{3/2}$ transitions and the hyperfine structure constant of the $7\,^2$S$_{1/2}$ and $6\,^2$D$_{3/2}$ states in $^{213}$Ra$^+$ were measured. These values provide a benchmark for the required atomic theory. A lower limit of $232(4)$ ms for the lifetime of the metastable $6\,^2$D$_{5/2}$ state was measured by optical shelving.
Observation of Cold Collisions between Trapped Ions and Trapped Atoms
我们展示了一个双阱系统，非常适合于研究被困离子和被困原子之间的冷碰撞。使用Yb $^+$离子被限制在一个保罗陷阱和Yb原子的磁光阱，我们研究了几种同位素的碰撞能量下降到400 neV（5 mK）的电荷交换碰撞。在原子极化率为143 a. u时，测量的$6 \times 10^{-10}$ cm $^{3}$ s $^{-1}$的速率系数在碰撞能量的四个数量级上是常数，与半经典Langevin模型的结果符合得很好.
We propose and demonstrate a new method for Doppler cooling trapped-ion crystals where the distribution of micromotion amplitudes may be large and uneven. The technique uses pulses of Doppler cooling light synchronized with the trap RF that selectively target ions when their velocity is near a node, leading to more uniform cooling across a crystal by a single tone of cooling light. We lay out a theoretical framework that describes where this technique is practical, and provide a simple experimental demonstration.
Isotope Shifts of the $6d\,^2$D$_{3/2}\,$ - $7p\,^2$P$_{1/2}\,$ Transition in Trapped Short-Lived $^{209-214}$Ra$^+$
在线性Paul阱中进行了短寿命镭同位素的激光光谱学研究。测量了$^{209-214}$ Ra $^+$中$6d\,^2$ D $_{3/2}\,$-$7p\,^2$ P $_{1/2}\,$跃迁的同位素位移，它对原子波函数的短程部分很敏感。这些结果为提高原子结构计算的精度提供了必要的实验依据。这是必不可少的宇称破坏Ra $^+$旨在确定弱混合角。
We measured the ground-state hyperfine splitting of trapped ${}^{113}$Cd${}^{+}$ ions to be 15199862855.02799(27) Hz with a fractional uncertainty of $1.8\times10^{-14}$. The ions were trapped and laser-cooled in a linear quadrupole Paul trap. The fractional frequency stability was measured to be ${4.2} \times 10^{-13}/\sqrtτ $, obtained from Ramsey fringes of high signal-to-noise ratio and taken over a measurement time of nearly 5 hours, which is close to the short-term stability limit estimated from the Dick effect. Our result is consistent with previous reported values, but the measurement …
Doppler cooling with lasers is essential to ions' trapping and also a preliminary step towards achievement of ultracold ions. Due to lack of effective tools, experimentally monitoring the ions' temperature and the laser-ion coupling is difficult in Doppler cooling. Here we analytically explore the Doppler cooling process of trapped ions, exemplified by $^{40}$Ca$^{+}$, by solving the friction coefficient in the Doppler cooling with respect to a thermal bath, particularly, to a bath with large heating rate. We show four regions for cooling and heating induced by the three-level electromagnetica…
In this chapter, we present an overview of experiments with trapped Rydberg ions and outline the advantages and challenges of developing applications of this new platform for quantum computing, sensing and simulation. Trapped Rydberg ions feature several important properties, unique in their combination: they are tightly bound in a harmonic potential of a Paul trap, in which their internal and external degrees of freedom can be controlled in a precise fashion. High fidelity state preparation of both internal and motional states of the ions has been demonstrated, and the internal states have be…
We consider the practical feasibility of using the direct, electric dipole-dipole interaction between co-trapped molecular ions for robust quantum logic without the need for static polarizing fields. The use of oscillating dipole moments, as opposed to static electric dipoles, dynamically decouples the dipoles from laboratory fields, including the electric fields of the trap itself. Further, this implementation does not require quantum control of motion, potentially removing a major roadblock to ion trap quantum computing scalability. Since the polarizing field is electromagnetic radiation, ev…
Distribution of the entangled state of trapped atomic ions to long distance using quantum repeater protocol is considered. Indeed, the long distance is divided into short parts, and then using entanglement generation and entanglement swapping techniques in optomechanical cavities, the entanglement is distributed. To do the task, we perform interaction between trapped atomic ions in optomechanical cavities, operate proper measurements on trapped ions and also make Bell state measurement as a well-known way to swap the entanglement. Accordingly, the entanglement is distributed between target ion…
We investigate the energy dynamics of non-crystallized (melted) ions, confined in a Paul trap. The non-periodic Coulomb interaction experienced by melted ions forms a medium for non-conservative energy transfer from the radio-frequency (rf) field to the ions, a process known as rf heating. We study rf heating by analyzing numerical simulations of non-crystallized ion motion in Paul trap potentials, in which the energy of the ions' secular motion changes at discrete intervals, corresponding to ion-ion collisions. The analysis of these collisions is used as a basis to derive a simplified model o…
Using discrete and continuous variable subsystems, hybrid approaches to quantum information could enable more quantum computational power for the same physical resources. Here, we propose a hybrid scheme that can be used to generate the necessary Gaussian and non-Gaussian operations for universal continuous variable quantum computing in trapped ions. This scheme utilizes two linear spin-motion interactions to generate a broad set of non-linear effective spin-motion interactions including one and two mode squeezing, beam splitter, and trisqueezing operations in trapped ion systems. We discuss p…
Demonstration of a dressed-state phase gate for trapped ions
我们演示了Bermudez等人提出的捕获离子纠缠门方案。[Phys. Rev. A 85，040302（2012）]。强载流子和单边带跃迁的同时激发使得能够确定性地产生纠缠态。该方法适用于磁场不敏感状态，对热激发是鲁棒的，包括从量子位退相误差的动态解耦，并且与具有捕获离子的一些其他纠缠门相比，在实验实现中提供了简化。我们实现了0.974（4）的贝尔态保真度，并确定了主要的误差来源。
We discuss a protocol for the analogue quantum simulation of superradiance and subradiance using a linear chain of N trapped qubit ions with a single sympathetic cooling ion. We develop a simple analytic model that shows the dynamics of the qubit subspace converge to those of a cloud undergoing Dicke superradiance and subradiance. We provide numerical simulations of the full ion chain and show that they converge to the dynamics predicted by our analytic model with no fitting parameters. We also map out the parameter regime needed to reach this convergence.
We propose and demonstrate phonon-number-resolving detection of the multiple local phonon modes in a trapped-ion chain. To mitigate the effect of phonon hopping during the detection process, the probability amplitude of each local phonon mode is mapped to the auxiliary long-lived motional ground states. Sequential state-dependent fluorescence detection is then performed. In the experiment, we have successfully observed the time evolution of two local phonon modes in two ions, including the phonon-number correlation between the two modes.
The two most widely used ion cooling methods are laser cooling and sympathetic cooling by elastic collisions (ECs). Here we demonstrate another method of cooling ions that is based on resonant charge exchange (RCE) between the trapped ion and the ultracold parent atom. Specifically, trapped Cs$^{+}$ ions are cooled by collisions with co-trapped, ultracold Cs atoms and, separately, by collisions with co-trapped, ultracold Rb atoms. We observe that the cooling of Cs$^{+}$ ions by Cs atoms is more efficient than cooling of Cs$^{+}$ ions by Rb atoms. This signals the presence of a cooling mechanis…
Surface-electrode trap with an integrated permanent magnet for generating a magnetic-field gradient at trapped ions
我们报告的表面电极陷阱与SmCo磁铁安排在一个四极配置下的陷阱电极。因为磁铁和被捕获的离子之间的距离可以小到几百微米，所以在没有任何热管理的情况下产生大的磁场。使用单个捕获的$^{40}$ Ca $^+$离子在几个位置处的塞曼分裂来测量磁场梯度，并且获得36 T/m的场梯度。这样的场梯度对于产生状态依赖力是有用的，这对于使用射频或微波辐射的量子模拟和/或量子门操作是重要的。
Thorium ions exhibit unique nuclear properties with high relevance for testing symmetries of nature, and Paul traps feature an ideal experimental platform for performing high precision quantum logic spectroscopy. Loading of stable or long-lived isotopes is well-established and relies on ionization from an atomic beam. A different approach allows trapping short-lived isotopes available as alpha-decay daughters, which recoil from a thin sample of the precursor nuclide. A prominent example is the short-lived $^{229\text{m}}$Th, populated in a decay of long-lived $^{233}$U. Here, ions are provided…
Generating quantum entanglement in large systems on time scales much shorter than the coherence time is key to powerful quantum simulation and computation. Trapped ions are among the most accurately controlled and best isolated quantum systems with low-error entanglement gates operated via the vibrational motion of a few-ion crystal within tens of microseconds. To exceed the level of complexity tractable by classical computers the main challenge is to realise fast entanglement operations in large ion crystals. The strong dipole-dipole interactions in polar molecule and Rydberg atom systems all…
