超流$^4$ He中的布朗运动
Brownian motion in superfluid $^4$He
摘要：
本文利用激光技术研究了超流体$^4$ He中经典微球的布朗运动，作为对量子流体中准粒子热涨落的直接研究。通过计算摩擦系数和随机力的强度的温度依赖性，我们表明，波动运动的共振模式可以完全解决本技术。与前人的工作相反，发现在温度高于0. 76 K时，转动子的贡献是不可忽略的，甚至成为主导.
英文摘要：
We propose to study the Brownian motion of a classical microsphere submerged in superfluid $^4$He using the recent laser technology as a direct investigation of the thermal fluctuations of quasiparticles in the quantum fluid. By calculating the temperature dependence of both the friction coefficient and the strength of the random force, we show that the resonant mode of the fluctuational motion can be fully resolved by the present technology. Contrary to the previous work, it is found that the roton contribution is not negligible, and it even becomes dominant when the temperature is above 0.76\,K.
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