Broadening of the drumhead-mode spectrum due to in-plane thermal fluctuations of two-dimensional trapped ion crystals in a Penning trap
Broadening of the drumhead-mode spectrum due to in-plane thermal fluctuations of two-dimensional trapped ion crystals in a Penning trap
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DOI：
10.1103/physreva.102.053106
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发表时间：
2020-08
期刊：
影响因子：
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通讯作者：
Athreya Shankar;Chenzhi Tang;M. Affolter;K. Gilmore;D. Dubin;S. Parker;M. Holland;J. Bollinger
中科院分区：
文献类型：
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作者：
Athreya Shankar;Chenzhi Tang;M. Affolter;K. Gilmore;D. Dubin;S. Parker;M. Holland;J. Bollinger
储存在潘宁阱中的二维离子晶体是量子模拟和传感实验的领先平台。对于小振幅，这种晶体的平面外运动可以通过称为鼓面模式的离散正常模式来描述，其可以用于实现一系列量子信息协议。然而，多普勒冷却，甚至近基态冷却鼓面模式的晶体的实验观察揭示了一个未解决的鼓面模式谱。在这项工作中，我们建立了离子位置的面内热波动作为鼓面模式谱的加宽的主要贡献者。在这个过程中，我们演示了如何限制磁场导致非常规的面内正常模式，其平均势能和动能是不相等的。这个属性，反过来，有影响的采样程序需要选择在平面内的初始条件的分子动力学模拟。对于NIST潘宁陷阱的当前操作条件，我们的研究表明，在这个陷阱中产生的二维晶体进行面内势能波动的顺序为10 $ mK。因此，我们的研究激发了设计改进技术来冷却面内自由度的需要。
Two-dimensional crystals of ions stored in Penning traps are a leading platform for quantum simulation and sensing experiments. For small amplitudes, the out-of-plane motion of such crystals can be described by a discrete set of normal modes called the drumhead modes, which can be used to implement a range of quantum information protocols. However, experimental observations of crystals with Doppler-cooled and even near-ground-state-cooled drumhead modes reveal an unresolved drumhead mode spectrum. In this work, we establish in-plane thermal fluctuations in ion positions as a major contributor to the broadening of the drumhead mode spectrum. In the process, we demonstrate how the confining magnetic field leads to unconventional in-plane normal modes, whose average potential and kinetic energies are not equal. This property, in turn, has implications for the sampling procedure required to choose the in-plane initial conditions for molecular dynamics simulations. For current operating conditions of the NIST Penning trap, our study suggests that the two dimensional crystals produced in this trap undergo in-plane potential energy fluctuations of the order of $10$ mK. Our study therefore motivates the need for designing improved techniques to cool the in-plane degrees of freedom.