Kanne Thomas, Marnauza Mikelis, Olsteins Dags, Carrad Damon J, Sestoft Joachim E, de Bruijckere Joeri, Zeng Lunjie, Johnson Erik, Olsson Eva, Grove-Rasmussen Kasper, Nygård Jesper
Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
Nat Nanotechnol. 2021 Jul;16(7):776-781. doi: 10.1038/s41565-021-00900-9. Epub 2021 May 10.
Semiconductor-superconductor hybrids are widely used to realize complex quantum phenomena, such as topological superconductivity and spins coupled to Cooper pairs. Accessing new, exotic regimes at high magnetic fields and increasing operating temperatures beyond the state-of-the-art requires new, epitaxially matched semiconductor-superconductor materials. One challenge is the generation of favourable conditions for heterostructural formation between materials with the desired properties. Here we harness an increased knowledge of metal-on-semiconductor growth to develop InAs nanowires with epitaxially matched, single-crystal, atomically flat Pb films with no axial grain boundaries. These highly ordered heterostructures have a critical temperature of 7 K and a superconducting gap of 1.25 meV, which remains hard at 8.5 T, and therefore they offer a parameter space more than twice as large as those of alternative semiconductor-superconductor hybrids. Additionally, InAs/Pb island devices exhibit magnetic field-driven transitions from a Cooper pair to single-electron charging, a prerequisite for use in topological quantum computation. Semiconductor-Pb hybrids potentially enable access to entirely new regimes for a number of different quantum systems.
半导体 - 超导体混合材料被广泛用于实现复杂的量子现象，如拓扑超导性以及与库珀对耦合的自旋。要在高磁场下进入新的奇异区域并提高工作温度，超越当前的技术水平，就需要新型的、外延匹配的半导体 - 超导体材料。其中一个挑战是为具有所需特性的材料之间的异质结构形成创造有利条件。在此，我们利用对半导体上金属生长的更多了解，开发出了具有外延匹配的单晶、原子级平整且无轴向晶界的Pb薄膜的InAs纳米线。这些高度有序的异质结构的临界温度为7 K，超导能隙为1.25 meV，在8.5 T磁场下仍保持稳定，因此它们提供的参数空间比其他半导体 - 超导体混合材料的参数空间大两倍多。此外，InAs/Pb岛状器件表现出从库珀对到单电子充电的磁场驱动转变，这是用于拓扑量子计算的一个先决条件。半导体 - Pb混合材料有可能为许多不同的量子系统开启全新的领域。
