High sensitivity, levitated microsphere apparatus for short-distance force measurements
High sensitivity, levitated microsphere apparatus for short-distance force measurements
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DOI：
10.1063/5.0011759
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发表时间：
2020-08-01
影响因子：
1.6
通讯作者：
Gratta, Giorgio
中科院分区：
文献类型：
--
作者：
Kawasaki, Akio;Fieguth, Alexander;Gratta, Giorgio
介绍了一种基于真空介质微球的高灵敏度力传感器，该传感器被一束向上传播的激光光捕获。离轴抛物面镜用于聚焦1064 nm的捕获光束并将其准直以提供微球水平位置的信息。垂直自由度通过在微球回射的光和参考光束之间形成干涉仪来读出，因此消除了对辅助光束的需要。捕获光束的焦点具有3.2 μ m的1/E-2半径和小的非高斯尾部，适合于使器件接近被捕获的微球而不干扰光场。围绕捕获区域的电极提供了对电场的极好控制，其可用于驱动带电微球的平移自由度和中性微球的旋转自由度，耦合到其电偶极矩。通过这种控制，可以用单电子精度确定电荷状态，可以测量单个微球的质量，并且可以对每个微球进行力灵敏度的经验校准。一种力噪声，
A high sensitivity force sensor based on dielectric microspheres in vacuum, optically trapped by a single, upward-propagating laser beam, is described. Off-axis parabolic mirrors are used both to focus the 1064 nm trapping beam and to recollimate it to provide information on the horizontal position of the microsphere. The vertical degree of freedom is readout by forming an interferometer between the light retroreflected by the microsphere and a reference beam, hence eliminating the need for auxiliary beams. The focus of the trapping beam has a 1/E-2 radius of 3.2 mu m and small non-Gaussian tails, suitable for bringing devices close to the trapped microsphere without disturbing the optical field. Electrodes surrounding the trapping region provide excellent control of the electric field, which can be used to drive the translational degrees of freedom of a charged microsphere and the rotational degrees of freedom of a neutral microsphere, coupling to its electric dipole moment. With this control, the charge state can be determined with single electron precision, the mass of individual microspheres can be measured, and empirical calibrations of the force sensitivity can be made for each microsphere. A force noise of