Atoms start behaving as waves rather than classical particles if confined in spaces commensurate with their de Broglie wavelength. At room temperature this length is only about one ångström even for the lightest atom, hydrogen. This restricts quantum-confinement phenomena for atomic species to the realm of very low temperatures^1,2,3,4,5. Here, we show that van der Waals gaps between atomic planes of layered crystals provide ångström-size channels that make quantum confinement of protons apparent even at room temperature. Our transport measurements show that thermal protons experience a notably higher barrier than deuterons when entering van der Waals gaps in hexagonal boron nitride and molybdenum disulfide. This is attributed to the difference in the de Broglie wavelengths of the isotopes. Once inside the crystals, transport of both isotopes can be described by classical diffusion, albeit with unexpectedly fast rates comparable to that of protons in water. The demonstrated ångström-size channels can be exploited for further studies of atomistic quantum confinement and, if the technology can be scaled up, for sieving hydrogen isotopes.

如果将原子限制在与其de Broglie波长相对应的空间中，则它们将开始表现为波浪而不是经典粒子。在室温下，即使是最轻的原子氢，该长度也仅约一个ångström。这将原子种类的量子限制现象限制在非常低的温度范围^1,2,3,4,5。在这里，我们证明了层状晶体原子面之间的范德华间隙提供了ngström尺寸的通道，这些通道即使在室温下也能使质子的量子限制变得明显。我们的传输测量结果表明，当进入六方氮化硼和二硫化钼中的范德华间隙时，热质子比氘核具有更高的阻挡层。这归因于同位素的德布罗意波长的差异。一旦进入晶体内部，两种同位素的传输都可以通过经典扩散来描述，尽管其出乎意料的快于质子的速度与水中的质子相当。证明的Ångström尺寸通道可用于进一步研究原子量子限制，如果该技术可以扩大规模，则可用于筛分氢同位素。