Name: experimental methods for trapping ions using microfabricated surface ion traps
Uploaded: 2017-08-17T14:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps at JoVE.com

在信息技术研究中心 (增加) 支助方案 (IITP-2017-2015-0-00385) 和信通技术 R 和 #38;D 方案 (10043464, 发展的情况下, 这项研究得到了科学、信通技术部和未来规划 (MSIP) 的部分支持。用于通信系统的量子中继器技术, 由信息和 #38 研究所监督; 通信技术促进 (IITP)。

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作者没有什么可透露的。

本文提出了一种利用 microfabricated 表面离子阱捕获离子的方法。离子捕集系统的建设需要在各个研究领域的经验, 但以前没有详细描述。本文给出了 microfabricating 陷阱芯片的详细步骤, 并首次建立了捕集离子的实验装置。本文还提供了用于捕获174Yb+离子并尝试捕获离子的详细步骤。
在微细加工过程中遇到的一个重要障碍是介电层的沉积, 厚度超过10µm。在厚介质层的沉积过程中, 残余应力可以增强, 从而对介质膜造成损伤, 甚至破坏晶片。为了减少残余应力, 这通常是压缩, 一个缓慢的沉积速率应使用40。在本例中, 测量了110.4 兆帕的压缩应力, SiH 的 540 sccm 的沉积条件为:4的气体流量, 140 W 的 RF 功率, 1.9 乇的压力在 5-µm 膜厚度。但是, 这些工艺条件只提供粗略的参考, 因为这些条件对不同设备可能有很大的差异。为了减少累积应力的影响, 在所提出的方法中, 在晶圆的两侧分别沉积了3.5 µm 厚的 alternatingly 膜 (2薄膜。如果选择更小的射频电压幅值, 从而降低所需的介质层厚度, 则可以减小所要求的介电常数。然而, 较浅的陷井深度容易导致被俘获离子的逃逸, 因此较厚的介电层的制作, 可以承受更高的射频电压, 更可取。
本文提出的制造方法有一定的局限性。悬垂的长度不足以完全隐藏被俘获离子的介电侧, 如图 7f所示。此外, 氧化物柱的侧是锯齿状的, 与垂直氧化柱相比, 增加了介电侧的暴露面积。例如, 在内部直流轨道的侧壁附近的加载槽与5µm 的均匀悬垂, 计算出33% 的介电表面暴露在垂直侧壁的被困离子位置。在锯齿状边缘的情况下, 超过70% 的侧壁面积暴露。这些非理想的制备结果可以从暴露的电介质中诱导出额外的杂散场, 但其影响尚未定量测量。然而, 上述所述的制造芯片已成功地应用于离子俘获和量子比特操纵实验。此外, 本文所提出的陷印芯片暴露在加载槽附近的硅侧。原生氧化物可以生长在硅表面, 并可能导致额外的杂散领域。因此, 建议使用附加的金属层来保护硅衬底, 如33中所示。
要捕获174Yb+离子, 激光器的频率应在几十 MHz 内稳定, 在高级设置38、41中讨论了几种不同的方法。但是, 对于本文所讨论的简单设置, 只有在使用波长计的情况下才可以进行初始陷印。
本文提供了一种使用 microfabricated 表面离子阱芯片捕获174Yb+离子的协议。虽然没有专门讨论陷印171yb+离子的协议, 但本文中描述的实验设置也可用于捕获171yb+离子并操纵171 的量子比特状态Yb+获得拉比振荡结果的离子 (如图 10所示)。这可以通过在激光器的输出中添加多个光调制器, 以及使用微波设置, 如补充文档中所述。
最后, 本文所提出的实验方法和结果可用于开发各种利用表面离子阱的量子信息应用。

保罗陷阱可以限制带电粒子, 包括空空间中的离子, 使用静态电场和在射频 (RF) 上振荡的变化电场的组合, 并且可以测量囚禁在阱中的离子的量子态, 并控制1,2,3。这种离子阱最初是为精确的测量应用而开发的, 包括光学时钟和质谱4,5,6。近年来, 这些离子阱也被作为一个物理平台进行了积极的探索, 以实现量子信息处理, 这归因于被困离子的可取特性, 如长相干时间, 理想隔离在超真空 (特高压) 环境, 以及单个量子比特操作的可行性7,8,9,10。自凯乌平斯基et al。11提出了可伸缩的离子阱体系结构, 可用于开发量子计算机、各种类型的表面陷阱, 包括连接陷阱12、13、多陷印芯片14和2维阵列陷阱15,16,17, 已开发使用半导体工艺衍生的微细加工方法18,19,20,21.基于表面陷阱的大规模量子信息处理系统也被讨论过22,23,24。
本文介绍了利用 microfabricated 表面离子阱捕获离子的实验方法。更具体地说, 一个制造表面离子阱的程序和一个详细的程序捕获离子使用的制造陷阱描述。此外, 在补充文档中还提供了有关设置实验系统和捕获离子的各种实用技术的详细说明。
在步骤1中给出了 microfabricating 表面离子阱的方法。图 1显示了一个表面离子阱的简化示意图。在横向平面上施加在电极上的电压所产生的电场也显示为25。rf 电压适用于 rf 电极对, 而所有其他电极则保留在 rf 地线上;射频电压产生的质电位26将离子限制在径向方向。直流 (dc) 电压适用于射频电极外的多个直流电极, 将离子限制在纵向方向。射频电极之间的内部轨道设计用来帮助倾斜横向平面中总电位的主轴。设计直流电压集的方法包括在辅助文档中。此外, 还可以在27、28、29、30、31中找到用于设计表面离子阱芯片基本几何参数的详细信息。
设计了步骤1中引入的制造方法, 考虑了以下几个方面。首先, 电极层和接地层之间的介电层应该足够厚, 以防止层间的电击穿。通常, 厚度应超过10µm。在厚介质层的沉积过程中, 沉积膜的残余应力会引起基体的弯曲或对沉积膜的损伤。因此, 控制残余应力是制备表面离子阱的关键技术之一。其次, 应尽量减少介质表面对离子位置的暴露, 因为散射电荷可以通过分散的紫外线 (UV) 激光器在介质材料上诱导, 从而导致离子位置的随机变化。通过设计悬置电极结构可以降低暴露面积。据报道, 在典型的实验条件下, 具有电极悬垂的表面离子阱对充电具有抗性,32。第三, 所有材料, 包括各种沉积薄膜, 应能够承受200° c 烘烤约2周, 并从所有材料的出气量应与特高压环境兼容。本文 microfabricated 的表面离子阱芯片的设计是基于从33的陷印设计, 它在各种实验中成功地使用了32、33、34、 35. 请注意, 此设计包括在芯片中间的一个插槽, 用于装入中性原子, 后来被照片电离以捕获。
在离子阱芯片的制造之后, 用金接合导线将芯片安装并电连接到芯片载体上。该芯片的载体, 然后安装在一个特高压室。在补充文档中提供了一个详细的程序, 用于准备陷阱芯片封装和超高压室的设计。
在步骤2中详细说明了光学和电气设备的制备, 以及捕集离子的实验程序。被质电位俘获的离子通常受周围电场的涨落的扰动, 从而不断增加离子的平均动能。基于多普勒变换的激光冷却可用于去除离子运动中多余的能量。图 2显示了174yb+离子和中性174yb 原子的简化的能级图。多普勒冷却的174Yb+离子需要 369.5 nm 激光器和 935 nm 激光器, 而中性174yb 原子的光电离则需要 399 nm 激光器。步骤2.2 和2.3 描述了将这些激光器与表面离子阱芯片对齐的有效方法, 并给出了一个寻找光电离的适当条件的程序。在光学和电子元件准备好后, 俘获离子相对简单。在步骤2.4 中给出了捕获离子的实验序列。

<table><tbody><tr><td>photoresist used for 2-&amp;mu;m spin coating</td><td>AZ Materials</td><td>AZ7220</td><td>Discontinued. Easily replaced by other alternative photoresist product.</td></tr><tr><td>photoresist used for 6-&amp;mu;m spin coating</td><td>AZ Materials</td><td>AZ4620</td><td>Discontinued. Easily replaced by other alternative photoresist product.</td></tr><tr><td>ceramic chip carrier</td><td>NTK</td><td>IPKX0F1-8180BA</td><td></td></tr><tr><td>epoxy compound</td><td>Epotek</td><td>353ND</td><td></td></tr><tr><td>Plasma enhanced chemical vapor deposition (PECVD) system</td><td>Oxford Instruments</td><td>PlasmaPro System100</td><td></td></tr><tr><td>Low pressure chemical vapor deposition (LPCVD) system</td><td>Centrotherm</td><td>E-1200</td><td></td></tr><tr><td>Furnace</td><td>Seltron</td><td>SHF-150</td><td></td></tr><tr><td>Sputter</td><td>Muhan Vacuum</td><td>MHS-1500</td><td></td></tr><tr><td>Manual aligner</td><td>Karl-Suss</td><td>MA-6</td><td></td></tr><tr><td>Deep Si etcher</td><td>Plasma-Therm</td><td>SLR-770-10R-B</td><td></td></tr><tr><td>Inductive coupled plasma (ICP) etcher</td><td>Oxford Instruments</td><td>PlasmaPro System100 Cobra</td><td></td></tr><tr><td>Reactive ion etching (RIE) etcher</td><td>Applied Materials</td><td>P-5000</td><td></td></tr><tr><td>Boundary element method (BEM) software</td><td>CPO Ltd.</td><td>Charged Particle Optics</td><td></td></tr><tr><td>Single crystaline (100) silicon wafer</td><td>STC</td><td>4SWP02</td><td>100 mm / (100) / P-type / SSP / 525&amp;plusmn;25 &amp;mu;m</td></tr><tr><td>metal tubes</td><td>Mcmaster-carr</td><td>89935K69</td><td>316 Stainless Steel Tubing, 0.042&quot; OD, 0.004&quot; Wall Thickness</td></tr><tr><td>Yb piece</td><td>Goodfellow</td><td>YB005110</td><td>Ytterbium wire, purity 99.9%</td></tr><tr><td>enriched &lt;sup&gt;171&lt;/sup&gt;Yb</td><td>Oak Ridge National Laboratory</td><td>Yb-171</td><td>https://www.isotopes.gov/catalog/product.php?element=Ytterbium</td></tr><tr><td>tantalum foil</td><td>The Nilaco Corporation</td><td>TI-453401</td><td>0.25x130x100mm 99.5%</td></tr><tr><td>Kapton-insulated copper wire</td><td>Accu-glass</td><td>18AWG (silver plated copper wire kapton insulted)</td><td></td></tr><tr><td>residual gas analyzer (RGA)</td><td>SRS</td><td>RGA200</td><td></td></tr><tr><td>turbo pump</td><td>Agilent</td><td>Twistorr84 FS</td><td></td></tr><tr><td>all-metal valve</td><td>KJL</td><td>manual SS All-Metal Angle Valves (CF flanged)</td><td></td></tr><tr><td>Leak detector (used as a rough pump)</td><td>Varian</td><td>PD03</td><td></td></tr><tr><td>ion gauges</td><td>Agilent</td><td>UHV-24p</td><td></td></tr><tr><td>ion pump</td><td>Agilent</td><td>VacIon Plus 20</td><td></td></tr><tr><td>NEG pump</td><td>SAES Getters</td><td>CapaciTorr D400</td><td></td></tr><tr><td>spherical octagon</td><td>Kimball Physics</td><td>MCF600-SphOct-F2C8</td><td></td></tr><tr><td>ZIF socket</td><td>Tactic Electronics</td><td>P/N 100-4680-002A</td><td></td></tr><tr><td>multi-pin feedthroughs</td><td>Accu-Glass</td><td>6-100531</td><td></td></tr><tr><td>25 D-sub gender adapters</td><td>Accu-Glass</td><td>104101</td><td></td></tr><tr><td>Recessed viewport</td><td>Culham Centre for Fusion Energy</td><td>100CF 316LN+20.9 Re-Entrant 316 (Custom order)</td><td>Disc material: 60cv Fused Silica 4mm THK, TWE Lambda 1/10, 20/10 Scratch-Dig</td></tr><tr><td>Recessed viewport AR coating</td><td>LaserOptik</td><td>AR355nm/0-6&amp;deg; HT370-650nm/0-36&amp;deg; on UHV (Custom order)</td><td>AR coating was performed in the middle of the fabrication of the recessed viewport</td></tr><tr><td>Digital-analog converter</td><td>AdLink</td><td>PCIe-6216V-GL</td><td></td></tr><tr><td>369.5nm laser</td><td>Toptica</td><td>TA-SHG Pro</td><td></td></tr><tr><td>369.5nm laser</td><td>Moglabs</td><td>ECD004 + 370LD10 + DLC102/HC</td><td></td></tr><tr><td>399nm laser</td><td>Toptica</td><td>DL 100</td><td></td></tr><tr><td>935nm laser</td><td>Toptica</td><td>DL 100</td><td></td></tr><tr><td>369.5nm &amp;amp; 399nm optical fiber</td><td>Coherent</td><td>NUV-320-K1</td><td>Patch cables are connectorized by Costal Connections.</td></tr><tr><td>935nm optical fiber</td><td>GouldFiber Optics</td><td>PSK-000626</td><td>50/50 fiber beam splitter made of Corning HI-780 single mode fiber to combine 935nm and 638nm together.</td></tr><tr><td>Wavelength meter</td><td>High Finesse</td><td>WSU-2</td><td></td></tr><tr><td>temporary mirror</td><td>Thorlabs</td><td>PF10-03-P01</td><td></td></tr><tr><td>Dichroic mirror</td><td>Semrock</td><td>FF647-SDi01-25x36</td><td></td></tr><tr><td>369.5nm &amp;amp; 399nm collimator</td><td>Micro Laser Systems</td><td>FC5-UV-T/A</td><td></td></tr><tr><td>935nm collimator</td><td>Sch&amp;auml;fter + Kirchhoff</td><td>60FC-0-M8-10</td><td></td></tr><tr><td>369.5nm focusing lens</td><td>CVI</td><td>PLCX-25.4-77.3-UV-355-399</td><td>Focal length: ~163mm @ 369.5nm</td></tr><tr><td>399nm &amp;amp; 935nm focusing lens</td><td>CVI</td><td>PLCX-25.4-64.4-UV-355-399</td><td>Focal length: ~137mm @ 399nm, ~143mm @ 935nm</td></tr><tr><td>imaging lens</td><td>Photon Gear</td><td>P/N 15470</td><td></td></tr><tr><td>369.5nm bandpass filter</td><td>Semrock</td><td>FF01-370/6-25</td><td></td></tr><tr><td>399nm bandpass filter</td><td>Semrock</td><td>FF01-395/11-25</td><td></td></tr><tr><td>IR filter</td><td>Semrock</td><td>FF01-650/SP-25</td><td></td></tr><tr><td>EMCCD camera</td><td>Andor Technology</td><td>DU-897U-CS0-EXF</td><td></td></tr><tr><td>PMT</td><td>Hamamatsu</td><td>H10682-210</td><td></td></tr></tbody></table>

experimental methods for trapping ions using microfabricated surface ion traps

离子被困在四极的保罗陷阱被认为是实现量子信息处理的强有力的物理候选之一。这是由于它们具有很长的相干时间和操纵和检测单个量子比特 (比特) 的能力。近年来, microfabricated 表面离子阱在 large-scale 集成量子比特平台中得到了越来越多的关注。本文介绍了一种利用微电-机械系统 (MEMS) 技术的离子阱的微细加工方法, 包括在介电层上的14µm 厚介质层和金属悬垂结构的制作方法。此外, 还介绍了利用 369.5 nm、399 nm 和 935 nm 二极管激光器捕获同位素 174 (174yb+) 的镱 (yb) 离子的实验方法。这些方法和程序涉及许多科学和工程学科, 本文首先介绍了详细的实验程序。本文所讨论的方法可以很容易地扩展到同位素 171 (171yb+) 的 yb 离子的捕获和量子比特的操作。

图 7显示了制造的离子阱芯片的扫描电子显微 (SEM)。成功地制备了射频电极、内直流电极、外直流电极和加载槽。由于 PECVD 氧化物沉积在几个步骤中, 介电柱的侧壁轮廓变得参差不齐。采用多沉积步骤, 使厚氧化物薄膜的残余应力最小化。在讨论中进一步介绍了这一点。

图 8显示了使用 microfabricated 离子阱芯片捕获的 EMCCD 五174Yb+离子的图像。在连续多普勒冷却下, 被俘获的离子可以持续超过24小时。通过改变所应用的直流电压集, 可在1和20之间调节被俘获离子的数量。这个实验装置是非常可靠和稳健的, 目前已经运行了50月。
图 9显示了沿轴向方向的被困离子的穿梭。图 9b中的离子位置通过改变直流电压来调整 dc 电位最小值的位置, 从而从图 9a中偏移。
图 10显示了具有171Yb+离子的拉比振荡实验的初步结果。为了获得结果, 使用了辅助文档中描述的其他设置。本文的研究结果表明了该实验装置的潜在应用。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56060/56060fig1.jpg"> 
图 1: 表面离子阱的示意图.(a) 红点代表被俘获的离子。棕色和黄色电极分别表示 RF 和直流电极。灰色箭头显示了射频电压正相位时电场的方向。请注意, 示意图不是按比例绘制的。(b) 电极结构的垂直尺寸。(c) 电极结构的侧面尺寸。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56060/56060fig2.jpg"> 
图 2: 174Yb+离子和中性的174yb 原子的简化的能级图。()当 369.5 nm 激光被谐到共振的红边 (较低频率) 时, 在2P1/2和21/2之间的循环转换将减少离子的动能, 因为多普勒影响.偶尔地, 一个小但有限的分支比率使电子衰变从2P1/2到2D3/2, 并且需要 935 nm 激光器返回电子回到主循环转换。电子也可以平均每小时衰变为2F7/2状态, 而 638 nm 激光器可以将其从2F7/2状态中抽出, 但对于简单系统38, 这不是必需的。动量中的值表示沿量化轴 mJ的总角 j 的投影。(b) 将电离中性原子从烤箱中蒸发出来, 用两个光子吸收过程进行了39。一个 399 nm 激光激发一个电子到1P1状态, 而 369.5 nm 光子的多普勒冷却有更多的能量比必要的, 以消除激发电子从离子。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56060/56060fig3.jpg"> 
图 3: 表面离子阱的制造工艺流程.(a) 热氧化生长一个5000Å厚的微 LPCVD2层和一个2000Å厚的 Si3N4层。(b) 沉积和 ICP 蚀刻1.5 µm 厚溅射铝层。(c) 在晶圆的两侧使用 PECVD 过程, 沉积一个14µm 厚的微相的2层。(d) 图案的14µm 厚的, 在硅片的前部, 使用一个µm 的过程 ( e) 图案的 14-厚的, 在背面的硅片上沉积的, 使用一个分度的过程.(f) 沉积一个1.5 µm 厚的溅射铝层和1µm 厚的 PECVD.2层。(g) 使用 ICP 处理的1.5 µm 厚铝层的图案和1µm 厚的微阵列的2层。(h) 图案的14µm 厚的微晶的2层沉积在前面的晶片使用一个以分度的过程。(i) 模式的5000Å-厚的微阵列的2层和2000Å厚的 Si3N4层使用了一个刻蚀过程。(j) DRIE 硅片背面的硅衬底450µm。(k) 在 Al 电极和介电柱的侧上的2层的湿刻蚀。(l) 通过 DRIE 过程从前端穿透硅衬底。请注意, 图表不是按比例绘制的。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56060/56060fig4.jpg"> 
图 4: 用于捕获离子的直流电压集的一个示例.应用于内轨的电压可以补偿水平方向的非对称电场, 使横向平面上总电位的主轴倾斜。由电压集产生的轴向阱频率为550赫。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
以太. 在页内 = "1" ><img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/56060/56060fig5v2.jpg"> 
图 5: 光学设置示意图.三二极管激光器被对准在陷印位置重叠。特高压室的凹进视口允许成像透镜尽可能靠近芯片表面。在成像透镜和 EMCCD 之间放置的翻转镜允许使用光子倍增管 (PMT) 或 EMCCD 对离子荧光进行选择性监测。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig5v2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/56060/56060fig6.jpg"> 
图 6: 构造的光学设置的图像。(a) 线圈缠绕在腔室的前视面上, 产生磁场, 从而能破坏镱离子的退化能级。(b) 用于指导 399 nm 和 935 nm 光束的光学装置。红线和绿线分别表示 935 nm 和 399 nm 激光器的光束轨迹。(c) 成像系统的配置, 包括翻转镜、成像透镜、EMCCD 和 PMT。从被俘获的离子中发出的荧光的路径可以由翻转镜来确定。绿色和白色箭头指示了 EMCCD 和 PMT 分别监测荧光的路径。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/56060/56060fig7.jpg"> 
图 7: 表面离子阱的制作结果.(a) 芯片布局概述。(b) 芯片布局的放大视图, 它显示了多个外部 DC 电极。(c) 芯片布局的放大视图, 显示加载插槽。(d) 在穿透加载槽之前对陷印区域进行剖面视图。(e) 穿透加载槽后的陷印区域的横截面视图。(f) 氧化物柱的放大截面视图。氧化物柱子有参差不齐的墙壁, 并且悬置的长度不是充足的, 归结于在分开地被存放的3.5 µm-厚实的微的一个被放置的2层之间的接口的一个不均匀的被腐蚀的率的孤立的2 。(g) DC 电极的引线键合垫的顶部视图。(h) 通过的横截面视图。氧化物柱的倾斜剖面允许在氧化物柱的侧壁上沉积铝层时, 直流电极和地面层的连接, 而不是通过电镀工艺填充孔。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig7large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/56060/56060fig8.jpg"> 
图 8: EMCCD 图像五174Yb+被困在 microfabricated 离子阱芯片上的离子.对表面陷阱电极结构的图像进行了分离, 并将捕获的离子和电极的图像结合起来以使其清晰。强度图例仅适用于框中的像素。粗箭头显示 369.5 nm 激光器的光束路径, 而细箭头表示光子动量的 x 和 z 分量。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig8large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/56060/56060fig9.jpg"> 
图 9: 在线性链中调整被困离子的轴向电位.(a) 七离子位于陷阱的中心。(b) 离子被穿梭数十微米。(c) 离子串被压缩在轴向方向。这个数字最好被视为电影, 这是单独上传。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig9large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 10" class="xfigimg" src="/files/ftp_upload/56060/56060fig10.jpg"> 
图 10: 0 和 | 1 <img alt="Image 1" src="/files/ftp_upload/56060/56060img1.jpg"> </img>状态之间的拉比振荡的实验结果<img alt="Image 1" src="/files/ftp_upload/56060/56060img1.jpg"> . | 0 定义为2S<img alt="Image 1" src="/files/ftp_upload/56060/56060img1.jpg"> </img> 1/2|F=0, mF=<img alt="Image 1" src="/files/ftp_upload/56060/56060img1.jpg"> </img> <img alt="Image 1" src="/files/ftp_upload/56060/56060img1.jpg"> </img> 0 状态的171Yb+离子, 和 | 1 被定义为2S1/2|F=1, mF= 0 状态.<img alt="Image 1" src="/files/ftp_upload/56060/56060img1.jpg"> </img>拉比振荡是由 12.6428 GHz 微波引起的。图中的布洛克球体在不同的时间显示相应的量子态。<a href="//ecsource.jove.com/files/ftp_upload/56060/56060fig10large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
补充文档:<a href="//ecsource.jove.com/files/ftp_upload/56060/jove-56060_Supplementary_Document.pdf" target="_blank">请单击此处下载此文档.</a>

Watch this Scientific Journal Video about Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps at JoVE.com

Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

本文介绍了一种表面离子阱的微细加工方法, 以及在室温环境中捕获镱离子的详细实验程序。

利用 Microfabricated 表面离子阱捕获离子的实验方法

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due ...

experimental-methods-for-trapping-ions-using-microfabricated-surface

Research

JoVE Journal

Engineering

13.6K 次观看.  Seoul National University. 本文介绍了一种表面离子阱的微细加工方法, 以及在室温环境中捕获镱离子的详细实验程序。

视频: Experimental Methods for Trapping Ions Using Microfabricated Surface Ion Traps

Optical Trapping of Nanoparticles

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3.
A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure.
The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm hydrodynamic radius bovine serum albumin proteins8. In this work, the experimental configuration used for nanoparticle trapping is outlined. First, we detail the assembly of the trapping setup which is based on a Thorlabs Optical Tweezer Kit. Next, we explain the nanofabrication procedure of the double-nanohole in a metal film, the fabrication of the microfluidic chamber and the sample preparation. Finally, we detail the data acquisition procedure and provide typical results for trapping 20 nm polystyrene nanospheres.

The following setup approach details low power optical trapping of dielectric nanoparticles using a double-nanohole in metal film.

纳米粒子的光学捕获

Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping ...

科研

工程学

A Microfluidic-based Hydrodynamic Trap for Single Particles

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in concentrated or crowded particle suspensions, which is difficult using alternative force field-based trapping methods. The hydrodynamic trap is user-friendly, straightforward to implement and may be added to existing microfluidic devices to facilitate trapping and long-time analysis of particles. Overall, the hydrodynamic trap is a new platform for confinement, micromanipulation, and observation of particles without surface immobilization and eliminates the need for potentially perturbative optical, magnetic, and electric fields in the free-solution trapping of small particles.

In this article, we present a microfluidic-based method for particle confinement based on hydrodynamic flow. We demonstrate stable particle trapping at a fluid stagnation point using a feedback control mechanism, thereby enabling confinement and micromanipulation of arbitrary particles in an integrated microdevice.

一个单粒子为基础的微流控液力陷阱

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science.  Methods for ...

生物工程

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

在质谱选择离子软着陆准备好定义的表面原位二次离子质谱和红外光谱

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

化学

On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids

Electrokinetic techniques are a staple of microscale applications because of their unique ability to perform a variety of fluidic and electrophoretic processes in simple, compact systems with no moving parts. Isotachophoresis (ITP) is a simple and very robust electrokinetic technique that can achieve million-fold preconcentration1,2 and efficient separation and extraction based on ionic mobility.3 For example, we have demonstrated the application of ITP to separation and sensitive detection of unlabeled ionic molecules (e.g. toxins, DNA, rRNA, miRNA) with little or no sample preparation4-8 and to extraction and purification of nucleic acids from complex matrices including cell culture, urine, and blood.9-12
ITP achieves focusing and separation using an applied electric field and two buffers within a fluidic channel system. For anionic analytes, the leading electrolyte (LE) buffer is chosen such that its anions have higher effective electrophoretic mobility than the anions of the trailing electrolyte (TE) buffer (Effective mobility describes the observable drift velocity of an ion and takes into account the ionization state of the ion, as described in detail by Persat et al.13). After establishing an interface between the TE and LE, an electric field is applied such that LE ions move away from the region occupied by TE ions. Sample ions of intermediate effective mobility race ahead of TE ions but cannot overtake LE ions, and so they focus at the LE-TE interface (hereafter called the "ITP interface"). Further, the TE and LE form regions of respectively low and high conductivity, which establish a steep electric field gradient at the ITP interface. This field gradient preconcentrates sample species as they focus. Proper choice of TE and LE results in focusing and purification of target species from other non-focused species and, eventually, separation and segregation of sample species.
We here review the physical principles underlying ITP and discuss two standard modes of operation: "peak" and "plateau" modes. In peak mode, relatively dilute sample ions focus together within overlapping narrow peaks at the ITP interface. In plateau mode, more abundant sample ions reach a steady-state concentration and segregate into adjoining plateau-like zones ordered by their effective mobility. Peak and plateau modes arise out of the same underlying physics, but represent distinct regimes differentiated by the initial analyte concentration and/or the amount of time allotted for sample accumulation.
We first describe in detail a model peak mode experiment and then demonstrate a peak mode assay for the extraction of nucleic acids from E. coli cell culture. We conclude by presenting a plateau mode assay, where we use a non-focusing tracer (NFT) species to visualize the separation and perform quantitation of amino acids.

Isotachophoresis (ITP) is a robust electrokinetic separation and preconcentration technique with applications ranging from toxin detection to sample preparation. We review the physical principles of ITP and the methodology of applying this technique to two specific example applications: separation and detection of small molecules and purification of nucleic acids from cell culture lysate.

对芯片等速电泳离子的分离和纯化核酸

Electrokinetic techniques are a staple of microscale applications because of their unique ability to perform a variety of fluidic and electrophoretic ...

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal&#8211;semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 &#937;&#8722;1 cm&#8722;1, with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

We describe the approaches for the device fabrication and electrical characterization of molybdenum diselenide (MoSe2) layer semiconductor nanostructures with different thicknesses. In addition, the fabrication of ohmic contacts for MoSe2-layer nanocrystals by the focused-ion beam deposition method using platinum (Pt) as a contact metal is described.

欧姆接触制造用聚焦离子束技术和电气特性的半导体层的纳米结构

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor ...

Microfluidic Pneumatic Cages: A Novel Approach for In-chip Crystal Trapping, Manipulation and Controlled Chemical Treatment

The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. Herein, we introduce a microfluidic-based technology, employing a double-layer microfluidic device, which can trap and localize in situ and ex situ synthesized structures on microfluidic channel surfaces. Crucially, we show how such a device can be used to conduct controlled chemical reactions onto on-chip trapped structures and we demonstrate how the synthetic pathway of a crystalline molecular material and its positioning inside a microfluidic channel can be precisely modified with this technology. This approach provides new opportunities for the controlled assembly of structures on surface and for their subsequent treatment.

Herein, we describe the fabrication and operation of a double-layer microfluidic system made of polydimethylsiloxane (PDMS). We demonstrate the potential of this device for trapping, directing the coordination pathway of a crystalline molecular material and controlling chemical reactions onto on-chip trapped structures.

微流控气动笼:在芯片水晶捕获，处理的新方法和控制化学处理

The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

介电微粒的光阱装载在空气中

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

电浆捕获和纳米粒子的释放在监控环境

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

Double-barreled and Concentric Microelectrodes for Measurement of Extracellular Ion Signals in Brain Tissue

Electrical activity in the brain is accompanied by significant ion fluxes across membranes, resulting in complex changes in the extracellular concentration of all major ions. As these ion shifts bear significant functional consequences, their quantitative determination is often required to understand the function and dysfunction of neural networks under physiological and pathophysiological conditions. In the present study, we demonstrate the fabrication and calibration of double-barreled ion-selective microelectrodes, which have proven to be excellent tools for such measurements in brain tissue. Moreover, so-called &#8220;concentric&#8221; ion-selective microelectrodes are also described, which, based on their different design, offer a far better temporal resolution of fast ion changes. We then show how these electrodes can be employed in acute brain slice preparations of the mouse hippocampus. Using double-barreled, potassium-selective microelectrodes, changes in the extracellular potassium concentration ([K+]o) in response to exogenous application of glutamate receptor agonists or during epileptiform activity are demonstrated. Furthermore, we illustrate the response characteristics of sodium-sensitive, double-barreled and concentric electrodes and compare their detection of changes in the extracellular sodium concentration ([Na+]o) evoked by bath or pressure application of drugs. These measurements show that while response amplitudes are similar, the concentric sodium microelectrodes display a superior signal-to-noise ratio and response time as compared to the double-barreled design. Generally, the demonstrated procedures will be easily transferable to measurement of other ions species, including pH or calcium, and will also be applicable to other preparations.

We demonstrate the fabrication, calibration and properties of two types of ion-selective microelectrodes (double-barreled and concentric) for measurement of ion concentrations in brain tissue. These are then used in the mouse hippocampal slice preparation to show that excitatory activity changes both extracellular potassium and sodium concentrations.

脑组织中的双管和同心微电极用于测量细胞外离子的信号

Electrical activity in the brain is accompanied by significant ion fluxes across membranes, resulting in complex changes in the extracellular ...

神经科学

Real-time Iontophoresis with Tetramethylammonium to Quantify Volume Fraction and Tortuosity of Brain Extracellular Space

This review describes the basic concepts and protocol to perform the real-time iontophoresis (RTI) method, the gold-standard to explore and quantify the extracellular space (ECS) of the living brain. The ECS surrounds all brain cells and contains both interstitial fluid and extracellular matrix. The transport of many substances required for brain activity, including neurotransmitters, hormones, and nutrients, occurs by diffusion through the ECS. Changes in the volume and geometry of this space occur during normal brain processes, like sleep, and pathological conditions, like ischemia. However, the structure and regulation of brain ECS, particularly in diseased states, remains largely unexplored. The RTI method measures two physical parameters of living brain: volume fraction and tortuosity. Volume fraction is the proportion of tissue volume occupied by ECS. Tortuosity is a measure of the relative hindrance a substance encounters when diffusing through a brain region as compared to a medium with no obstructions. In RTI, an inert molecule is pulsed from a source microelectrode into the brain ECS. As molecules diffuse away from this source, the changing concentration of the ion is measured over time using an ion-selective microelectrode positioned roughly 100 &#181;m away. From the resulting diffusion curve, both volume fraction and tortuosity can be calculated. This technique has been used in brain slices from multiple species (including humans) and in vivo to study acute and chronic changes to ECS. Unlike other methods, RTI can be used to examine both reversible and irreversible changes to the brain ECS in real time.

This protocol describes real-time iontophoresis, a method that measures physical parameters of the extracellular space (ECS) of living brains. The diffusion of an inert molecule released into the ECS is used to calculate the ECS volume fraction and tortuosity. It is ideal for studying acute reversible changes to brain ECS.

用四甲基铵进行实时离子电渗疗法，以量化体细胞分数和脑细胞外空间的变性

This review describes the basic concepts and protocol to perform the real-time iontophoresis (RTI) method, the gold-standard to explore and quantify the ...