Quantum phase transition of liquid helium in aerogel

气凝胶中液氦的量子相变

基本信息

批准号：
16540312
负责人：
MATSUMOTO Koichi
金额：
$ 2.3万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16540312/
关键词：
helium superfluidity ultrasound aerogel phase transition

项目摘要

We have presented evidence for quantum phase transition (QPT) on superfluid phase transition of helium 3 in 98% aerogel in 1997. However, the details of the QPT are not known so far. We studied the QPT of helium in aerogel for both helium 3 and 4 using ultrasound technique.1. helium 4 and aerogel systemQPT is reported for helium 4 in porous glass with small pore. We have studied superfluid transition of helium 4 in aerogel with porosity between 92 and 97 %. The transition was suppressed by aerogel. We have made the phase diagram for this system. However, QPT was not observed in aerogel. We have observed many interesting phenomena in this research. For example, anomalous sound attenuation was observed with 97 % porous aerogel around 1.7 K. This result suggested possibility of mode conversion between first, second sound in superfluid and aerogel sound mode in this composite system.Solidification of helium in aerogel was studied. Sound transmission trough the solid-liquid interface has been observed. Our experiment shows the crystal growth is suppressed by silica strands of aerogel.2. helium3 and aerogel systemA nuclear demagnetizing refrigerator has been constructed for this experiment. The sound cell has acoustic cavities with aerogel and bulk liquid for comparison. The signal with aerogel has been observed using longitudinal ultrasound at 6 MHz. Because of the trouble of refrigerator, only preliminary experimental data was obtained. The experiment is ongoing.

我们于1997年提出了98%气凝胶中氦3超流相变的量子相变（QPT）证据。然而，QPT的细节目前尚不清楚。我们利用超声技术研究了气凝胶中氦3和氦4的QPT。1．氦 4 和气凝胶系统QPT 据报道，氦 4 在小孔多孔玻璃中。我们研究了氦 4 在孔隙率 92% 至 97% 的气凝胶中的超流转变。该转变被气凝胶抑制。我们制作了该系统的相图。然而，在气凝胶中没有观察到QPT。我们在这项研究中观察到许多有趣的现象。例如，在 97% 多孔气凝胶中，在 1.7 K 左右观察到异常声音衰减。这一结果表明，在该复合系统中，超流体中的第一、第二声音与气凝胶声音模式之间存在模式转换的可能性。研究了气凝胶中氦的固化。已经观察到声音通过固液界面的传播。我们的实验表明，气凝胶的二氧化硅束抑制了晶体的生长。2．氦气和气凝胶系统为本实验建造了核消磁冰箱。声音单元具有带有气凝胶和散装液体的声腔以进行比较。使用 6 MHz 的纵向超声波观察到气凝胶的信号。由于冰箱的麻烦，只得到了初步的实验数据。实验正在进行中。

项目成果

期刊论文数量（25）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Porosity dependence of sound propagation in liquid 4He filled aerogel

液体 4He 填充气凝胶中声音传播的孔隙率依赖性

DOI：
发表时间：
2004
期刊：
JETP Lett 80
影响因子：
0
作者：
K.Matsumoto;Y.Matsuyama;D.A.Tayurskii;K.Tajiri
通讯作者：
K.Tajiri

Satoshi Abe, Haruhiko Suzuki; and Dmitrii Tayurskii Possible Sound Mode Conversion in "Superfluid 4He-97% Open Aerogel" System

Satoshi%20Abe,%20Haruhiko%20Suzuki;%20and%20Dmitrii%20Tayurskii%20Possible%20Sound%20Mode%20Conversion%20in%20"Superfluid%204He-97%%20Open%20Aerogel"%20System