Constantino Nicolas G N, Anwar Muhammad Shahbaz, Kennedy Oscar W, Dang Manyu, Warburton Paul A, Fenton Jonathan C
London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK.
Nanomaterials (Basel). 2018 Jun 16;8(6):442. doi: 10.3390/nano8060442.
Superconducting nanowires undergoing quantum phase-slips have potential for impact in electronic devices, with a high-accuracy quantum current standard among a possible toolbox of novel components. A key element of developing such technologies is to understand the requirements for, and control the production of, superconducting nanowires that undergo coherent quantum phase-slips. We present three fabrication technologies, based on using electron-beam lithography or neon focussed ion-beam lithography, for defining narrow superconducting nanowires, and have used these to create nanowires in niobium nitride with widths in the range of 20⁻250 nm. We present characterisation of the nanowires using DC electrical transport at temperatures down to 300 mK. We demonstrate that a range of different behaviours may be obtained in different nanowires, including bulk-like superconducting properties with critical-current features, the observation of phase-slip centres and the observation of zero conductance below a critical voltage, characteristic of coherent quantum phase-slips. We observe critical voltages up to 5 mV, an order of magnitude larger than other reports to date. The different prominence of quantum phase-slip effects in the various nanowires may be understood as arising from the differing importance of quantum fluctuations. Control of the nanowire properties will pave the way for routine fabrication of coherent quantum phase-slip nanowire devices for technology applications.
经历量子相位滑移的超导纳米线在电子设备中具有潜在影响，在一系列可能的新型组件中有望成为高精度量子电流标准。开发此类技术的一个关键要素是了解对经历相干量子相位滑移的超导纳米线的要求，并控制其生产。我们提出了三种基于电子束光刻或氖聚焦离子束光刻的制造技术，用于定义窄超导纳米线，并已使用这些技术在氮化铌中制造出宽度在20⁻250纳米范围内的纳米线。我们展示了在低至300 mK的温度下使用直流电输运对纳米线进行的表征。我们证明，在不同的纳米线中可以获得一系列不同的行为，包括具有临界电流特征的块状超导特性、相位滑移中心的观测以及低于临界电压时零电导的观测，这是相干量子相位滑移的特征。我们观测到高达5 mV的临界电压，比迄今为止的其他报告大一个数量级。各种纳米线中量子相位滑移效应的不同显著程度可以理解为源于量子涨落的不同重要性。对纳米线特性的控制将为用于技术应用的相干量子相位滑移纳米线器件的常规制造铺平道路。
