Quantized current steps due to the a.c. coherent quantum phase-slip effect.
Quantized current steps due to the a.c. coherent quantum phase-slip effect.
复制标题
由于交流而产生的量化电流阶跃
DOI：
10.1038/s41586-022-04947-z
复制
发表时间：
2022
期刊：
影响因子：
64.8
通讯作者：
Shaikhaidarov RS
中科院分区：
文献类型：
--
作者：
Shaikhaidarov RS
的交流约瑟夫森效应在1962年被预言，并在1963年被实验观察到，作为库珀对的光子辅助隧穿的量子化“电压阶跃”（夏皮罗阶跃），是量子力学中最基本的现象之一，对量子电压标准至关重要。物理上的双重效应，交流。相干量子相位滑移（CQPS），通过超导纳米线的磁通量的光子辅助隧穿，被设想为量子化的“电流阶跃”。交流的基本物理意义。CQPS在未来的现行标准中也具有实际重要性，这是关闭量子计量三角形的一个缺失元素。2012年，CQPS被证明是超导纳米线中磁通量子的叠加。然而，由于缺乏合适的材料和电路工程的挑战，超导体中的直流平坦电流阶跃是迄今为止唯一无法实现的超导基本效应。在这里，我们报告的超导纳米线的双夏皮罗步骤的直接观察。在高达26 GHz的频率下，电流值为8.3 nA，并且受到当前设置带宽的限制，这些尖锐的阶跃是清晰的。30年前，理论上预测了小约瑟夫森结中的电流阶跃。然而，约瑟夫森结中不可避免的加宽阻碍了它们的直接实验观察。我们解决了这个问题，通过将薄的NbN纳米线在电感环境中。
The a.c. Josephson effect predicted in 1962 and observed experimentally in 1963 as quantized ‘voltage steps’ (the Shapiro steps) from photon-assisted tunnelling of Cooper pairs is among the most fundamental phenomena of quantum mechanics and is vital for metrological quantum voltage standards. The physically dual effect, the a.c. coherent quantum phase slip (CQPS), photon-assisted tunnelling of magnetic fluxes through a superconducting nanowire, is envisaged to reveal itself as quantized ‘current steps’,. The basic physical significance of the a.c. CQPS is also complemented by practical importance in future current standards, a missing element for closing the quantum metrology triangle,. In 2012, the CQPS was demonstrated as superposition of magnetic flux quanta in superconducting nanowires . However, the direct flat current steps in superconductors, the only unavailable basic effect of superconductivity to date, was unattainable due to lack of appropriate materials and challenges in circuit engineering. Here we report the direct observation of the dual Shapiro steps in a superconducting nanowire. The sharp steps are clear up to 26 GHz frequency with current values 8.3 nA and limited by the present set-up bandwidth. The current steps were theoretically predicted in small Josephson junctions 30 years ago. However, unavoidable broadening in Josephson junctions prevents their direct experimental observation,. We solve this problem by placing a thin NbN nanowire in an inductive environment.