Probing Quantum Turbulence in ^{4}He by Quantum Evaporation Measurements.
Probing Quantum Turbulence in ^{4}He by Quantum Evaporation Measurements.
复制标题
通过量子蒸发测量探测 ^{4}He 中的量子湍流。
DOI：
10.1103/physrevlett.121.015302
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发表时间：
2018
影响因子：
8.6
通讯作者：
L. Reatto
中科院分区：
文献类型：
--
作者：
I. Amelio;D. Galli;L. Reatto
超流理论表明，由于强关联和回流效应，涡旋线的密度分布具有密度调制的特征，而不是冷玻色原子云中的简单稀疏区。我们发现，这种密度调制的基本特征是一个圆柱对称的波包，其中具有正群速度的旋子占主导地位：涡旋密度调制可以看作是由涡旋波函数的相位支撑的虚激发的云，主要是旋子。这表明，在涡旋重联中，其中一些旋子变成了真实的，因此涡旋纠缠被预测为非热旋动子的来源。这种涡旋诱导旋量的存在可以通过测量^{4}He原子的量子蒸发温度来证实。我们估计了蒸发的速度，事实证明这是目前的仪器可以检测到的。如果探测到高能声子的量子蒸发，将获得有关量子湍流衰变的微观过程的额外信息。
Theory of superfluid ^{4}He shows that, due to strong correlations and backflow effects, the density profile of a vortex line has the character of a density modulation and it is not a simple rarefaction region as found in clouds of cold bosonic atoms. We find that the basic features of this density modulation are represented by a wave packet of cylindrical symmetry in which rotons with a positive group velocity have a dominant role: The vortex density modulation can be viewed as a cloud of virtual excitations, mainly rotons, sustained by the phase of the vortex wave function. This suggests that in a vortex reconnection some of these rotons become real so that a vortex tangle is predicted to be a source of nonthermal rotons. The presence of such vorticity induced rotons can be verified by measurements at low temperature of quantum evaporation of ^{4}He atoms. We estimate the rate of evaporation and this turns out to be detectable by current instrumentation. Additional information on the microscopic processes in the decay of quantum turbulence will be obtained if quantum evaporation by high energy phonons should be detected.