Join project of Study on Polarized Atomic Hydrogen

由于大的量子性质，极化的氢原子即使在绝对零度时也处于气相中，这种简单而最量子的气体探索了量子系统的许多有趣的特征。如果足够高密度的极化原子氢能够在低温下冷却，就可以在这种气体中预测玻色-爱因斯坦凝聚(BEC)。然而，事实证明，在体积和高密度的气体中不能到达BEC，他们正在寻找被磁捕获的气体中的BEC，因此BEC的密度相对较低。京都大学和库尔查托夫研究所一直在研究吸收在液氦表面的极化原子氢。这些氢原子形成了近乎理想的二维玻色气体，并可能成为二维超流体(Kosteritz-Thouless转变)。两个小组之间的合作重点是寻找K-T转变。通过这次合作，京都研究了吸附在超流氦上的二维氢的冷却机制，发现^3He-^4He超流膜上的氢被冷却到了几个10mK。库尔恰诺夫小组研究了强局部磁场下氦膜上吸收的氢，发现这种氢与K-T相变非常交叉。目前，京都正在利用库尔恰诺夫的mm-ESR设备为京都的氢气设备建立合作实验。我们在京都观测到了127 GHz的原子氢-ESR信号。明年，我们将继续合作，尝试探测二维氢信号，并在这个系统中寻找K-T转变。

Polarized atomic hydrogen is in a gas phase even at absolute zero degree due to large quantum nature, and this simple and most quantum gas has explored many interesting features of quantum system. The Bose-Einstein condensation (BEC) has been predicted in this gas if polarized atomic hydrogen with a sufficient high density can be cooled at low temperatures. However, it turns out that the BEC can not be reached in a bulk and high- density gas and they are searching the BEC in the gas which is magnetically-trapped and thus with a relatively low density.Kyoto University and kurchatov Institute has been working on polarized atomic hydrogen absorbed on liquid helium surface. This hydrogen atoms forms the almost ideal 2-dimensional Bose gas and may become the two-dimensional superfluid (Kosteritz-Thouless Transition). Collaboration between two groups are focused on the search of the K-T transition. Through the collaboration, Kyoto studied cooling mechanisms of two-dimensional hydrogen absorbed on superfluid He and found that hydrogen on ^3He-^4He superfluid film was cooled well down to several 10 mK.kurchatov group investigated hydrogen absorbed on helium films around a strong local magnetic field and found that this hydrogen were very cross to the K-T transition.Now collaboration experiment are setting up at Kyoto for Kyoto's hydrogen equipment by using Kurchatov's mm-ESR equipments. We observed the atomic hydrogen-ESR signal at 127 GHz in Kyoto. In next year, we continue the collaboration and try to detect the two-dimensional hydrogen signal and to search for the K-T transition in this system.