Current–phase relations of few-mode InAs nanowire Josephson junctions
Current–phase relations of few-mode InAs nanowire Josephson junctions
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DOI：
10.1038/nphys4224
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发表时间：
2017-01
期刊：
影响因子：
19.6
通讯作者：
E. Spanton;M. Deng;S. Vaitiekėnas;P. Krogstrup;J. Nygård;C. Marcus;K. Moler
中科院分区：
文献类型：
--
作者：
E. Spanton;M. Deng;S. Vaitiekėnas;P. Krogstrup;J. Nygård;C. Marcus;K. Moler
具有超导引线的栅极可调半导体纳米线在量子计算以及作为介观约瑟夫森结的模型系统方面具有巨大的潜力。穿过交叉口的电流I与相位φ之间的关系称为电流-相位关系(CPR)。它不仅可以显示临界电流的大小，而且还可以显示模式的数目和它们的传输。我们测量了许多单独的InAs纳米线约瑟夫森结的CPR，一次一个结。CPR的幅度和形状在不同的结点之间不同，小的临界电流和偏斜的CPR表示高传输的少模结点。在栅极可调谐的结中，我们发现CPR随栅极电压而变化：在超流开始附近，我们观察到与通过单一的高传输模式的共振隧穿一致的行为。栅极依赖关系与模型化的子带结构一致，该子带结构包括由于栅调谐区边界的费米能级突变而产生的有效隧穿势垒。这些偏斜、可调、少模CPR的测量既适用于需要非谐结的应用，也适用于Majorana读出方案。
Gate-tunable semiconductor nanowires with superconducting leads have great potential for quantum computation,,and as model systems for mesoscopic Josephson junctions,. The supercurrent,I, versus the phase,φ, across the junction is called the current–phase relation (CPR). It can reveal not only the amplitude of the critical current, but also the number of modes and their transmission. We measured the CPR of many individual InAs nanowire Josephson junctions, one junction at a time. Both the amplitude and shape of the CPR varied between junctions, with small critical currents and skewed CPRs indicating few-mode junctions with high transmissions. In a gate-tunable junction, we found that the CPR varied with gate voltage: near the onset of supercurrent, we observed behaviour consistent with resonant tunnelling through a single, highly transmitting mode. The gate dependence is consistent with modelled subband structure that includes an effective tunnelling barrier due to an abrupt change in the Fermi level at the boundary of the gate-tuned region. These measurements of skewed, tunable, few-mode CPRs are promising both for applications that require anharmonic junctions,and for Majorana readout proposals.