Micromotion in trapped atom-ion systems
Micromotion in trapped atom-ion systems
复制标题
俘获原子离子系统中的微运动
DOI：
10.1103/physreva.85.052718
复制
发表时间：
2012
影响因子：
2.9
通讯作者：
B. Englert
中科院分区：
文献类型：
--
作者：
L. Nguyen;A. Kalev;M. Barrett;B. Englert
我们在有关被捕获原子和单个被捕获离子的受控碰撞问题中检查了谐波近似的有效性，其中射频离子陷阱被视为谐波陷阱。这相当于研究微运动的影响，因为必须忽略这种运动才能将捕获的离子视为谐振子。通过应用库克和香克兰的变换，我们发现微运动可以用两个周期性振荡算子来表示。为了研究微动对俘获原子离子系统动力学的影响，我们通过数值积分计算了微动算子的耦合强度，以及（ii）通过应用 Floquet 形式（研究周期系统的有用框架）计算了系统的准能量。事实证明，当原子和离子陷阱之间的距离短于特征距离时，微运动不可忽略。在此范围内，当考虑微运动时，系统的能量图会发生显着变化，这会给基于捕获原子离子系统绝热过程的应用带来不良后果。我们提出了一种绕过微动效应的简单方案，以便成功实现先前提出的量子控制相位门并创建原子离子高分子。这里提出的方法并不限于捕获的原子离子系统，并且可以很容易地应用于研究涉及单个捕获离子的任何系统中的微动效应。
We examine the validity of the harmonic approximation, where the radio-frequency ion trap is treated as a harmonic trap, in the problem regarding the controlled collision of a trapped atom and a single trapped ion. This is equivalent to studying the effect of the micromotion since this motion must be neglected for the trapped ion to be considered as a harmonic oscillator. By applying the transformation of Cook and Shankland we find that the micromotion can be represented by two periodically oscillating operators. In order to investigate the effect of the micromotion on the dynamics of a trapped atom-ion system, we calculate (i) the coupling strengths of the micromotion operators by numerical integration and (ii) the quasienergies of the system by applying the Floquet formalism, a useful framework for studying periodic systems. It turns out that the micromotion is not negligible when the distance between the atom and the ion traps is shorter than a characteristic distance. Within this range the energy diagram of the system changes remarkably when the micromotion is taken into account, which leads to undesirable consequences for applications that are based on an adiabatic process of the trapped atom-ion system. We suggest a simple scheme for bypassing the micromotion effect in order to successfully implement a quantum controlled phase gate proposed previously and create an atom-ion macromolecule. The methods presented here are not restricted to trapped atom-ion systems and can be readily applied to studying the micromotion effect in any system involving a single trapped ion.