Mesoscopic Superfluid 3He

超流3He是最有序和最纯的凝聚态系统，因此人们观察和研究了各种类型的量子化涡旋和其他其有序的缺陷。当超流3He变成二维时，预计会出现新类型的涡旋。虽然对这种涡旋的理解本身是基本的，但它为我们理解非常规超导体和宇宙弦铺平了道路。我们将研究降维超流3He中的涡旋物理。新的研究方向可以通过使用物理和天文学院不同研究小组的罕见专业知识组合来启动。戈洛夫的团队在研究超流氦方面有着长期的经验，并拥有一台独特的旋转低温恒温器，可以在超流3He中产生漩涡。盖姆的团队将通过直接接触现代微制造设施和介观物理方面的广泛专业知识，包括介观超导体中的涡旋物理，为该项目做出贡献。我们打算用人工制造的亚微米级的周期性凸起阵列(涡旋的钉扎中心)来研究受平坦边界约束的超流3He薄板中的量子化涡旋。3He在薄片几何结构中的性质应该在许多方面与块体超流体的性质不同，例如，有望形成环量仅为环量一半的新型涡旋。使用我们的旋转低温恒温器，我们将引入所需密度的涡旋，同时将3He保持在0.9MK的超流转变温度以下。通过纳米钉扎中心阵列，我们期望观察到当涡旋和钉扎中心阵列的密度匹配时的可公度性效应。这将提供涡旋密度的直接测量，并允许我们找出在某些实验条件下涡旋是否可以变得分数。

Superfluid 3He is the most ordered and pure condensed matter system, as a result various types of quantized vortices and other defects of its order were observed and studied. When superfluid 3He becomes two-dimensional, new types of vortices are expected. While fundamental on its own, understanding of such vortices paves way to our understanding of unconvensional superconductors and cosmic strings. We will study the vortex physics in superfluid 3He of reduced dimensions. The new research direction can be initiated by using a rare combination of expertise from different research groups in the School of Physics and Astronomy. Golov's group has a long-term experience in studies of superfluid helium and possesses a unique rotating cryostat for creating vortices in superfluid 3He. Geim's group will contribute to the project through its direct access to modern microfabrication facilities and extensive expertise in mesoscopic physics, including the physics of vortices in mesoscopic superconductors. We intend to study quantized vortices in thin slabs of superfluid 3He confined by flat boundaries with artificially fabricated periodic arrays of submicron bumps (pinning centres for vortices). The properties of 3He in thin-slab geometry should differ from those of bulk superfluid in many respects, for example, new type of vortices with circulation equal to just one half of circulation quantum are expected. With our rotating cryostat, we will introduce vortices of required density while keeping the 3He below its superfluid transition temperature of 0.9 mK. With arrays of nanofabricated pinning centres, we expect to observe commensurability effects when densities of the arrays of vortices and pinning centres match. This will provide a direct measure of the vortex density and, among other things, should allow us to find out whether vortices can become fractional under certain experimental conditions.