Abstract When a neutral sphere is rotating near a surface in vacuum, it will experience a frictional torque due to quantum and thermal electromagnetic fluctuations. Such vacuum friction has attracted many interests but has been too weak to be observed. Here we investigate the vacuum frictional torque on a barium strontium titanate (BST) nanosphere near a BST surface. BST is a perovskite ferroelectric ceramic that can have large dielectric responses at GHz frequencies. At resonant rotating frequencies, the mechanical energy of motion can be converted to electromagnetic energy through resonant photon tunneling, leading to a large enhancement of the vacuum friction. The calculated vacuum frictional torques at resonances at sub-GHz and GHz frequencies are several orders larger than the minimum torque measured by an optically levitated nanorotor recently, and are thus promising to be observed experimentally. Moreover, we calculate the vacuum friction on a rotating sphere near a layered surface for the first time. By optimizing the thickness of the thin-film coating, the frictional torque can be further enhanced by several times.

中文翻译：

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通过表面光子隧穿增强旋转真空摩擦

摘要 当一个中性球体在真空中的表面附近旋转时，会由于量子和热电磁涨落而产生摩擦力矩。这种真空摩擦引起了许多兴趣，但太弱而无法观察。在这里，我们研究了 BST 表面附近的钛酸锶钡 (BST) 纳米球上的真空摩擦扭矩。BST 是一种钙钛矿铁电陶瓷，在 GHz 频率下具有较大的介电响应。在共振旋转频率下，运动的机械能可以通过共振光子隧穿转换为电磁能，从而大大增强真空摩擦。计算出的 sub-GHz 和 GHz 频率共振下的真空摩擦扭矩比最近由光学悬浮纳米转子测量的最小扭矩大几个数量级，因此有望通过实验观察到。此外，我们首次计算了靠近分层表面的旋转球体上的真空摩擦。通过优化薄膜涂层的厚度，摩擦力矩可以进一步提高数倍。