The angstrom-scale coherence length describing the superfluid wavefunction of ${}^4$He at low temperatures has prevented its preparation in a truly one-dimensional geometry. Mesoporous ordered silica-based structures, such as the molecular sieve MCM-41, offer a promising avenue towards physical confinement, but the minimal pore diameters that can be chemically synthesized have proven to be too large to reach the quasi-one-dimensional limit. We present an active nano-engineering approach to this problem by pre-plating MCM-41 with a single, well controlled layer of Ar gas before filling the pores with helium. The structure inside the pore is investigated via experimental adsorption isotherms and neutron scattering measurements that are in agreement with large scale quantum Monte Carlo simulations. The results demonstrate angstrom and kelvin scale tunability of the effective confinement potential experienced by ${}^4$He atoms inside the MCM-41, with the Ar layer reducing the diameter of the confining media into a regime where a number of solid layers surround a one-dimensional quantum liquid.

中文翻译：

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镀氩的MCM-41纳米孔中He-4的尺寸减小

埃尺度相干长度描述了超流体的波函数 ${}^4$他在低温下阻止了其制备成真正的一维几何形状。介孔有序的二氧化硅基结构，例如分子筛MCM-41，为物理限制提供了一种有希望的途径，但是已经证明可以化学合成的最小孔径太大，无法达到准一维极限。我们提出了一种主动的纳米工程方法来解决此问题，方法是在氦气填充孔之前，先在MCM-41上预先镀上一层单一且受控良好的Ar气体，然后再进行电镀。通过实验吸附等温线和中子散射测量研究了孔内部的结构，这些测量与大规模量子蒙特卡洛模拟相符。结果表明，埃克朗和开尔文尺度的有效约束潜力具有可调谐性${}^4$他在MCM-41内原子化，而Ar层将限制介质的直径减小到一种状态，其中许多固体层围绕一维量子液体。