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Quantifying quantum coherence of multiple-charge states in tunable Josephson junctions
npj Quantum Information ( IF 6.6 ) Pub Date : 2024-01-02 , DOI: 10.1038/s41534-023-00798-2
Jiangbo He , Dong Pan , Mingli Liu , Zhaozheng Lyu , Zhongmou Jia , Guang Yang , Shang Zhu , Guangtong Liu , Jie Shen , Sergey N. Shevchenko , Franco Nori , Jianhua Zhao , Li Lu , Fanming Qu

Coherence and tunneling play central roles in quantum phenomena. In a tunneling event, the time that a particle spends inside the barrier has been fiercely debated. This problem becomes more complex when tunneling repeatedly occurs back and forth, and when involving many particles. Here we report the measurement of the coherence time of various charge states tunneling in a nanowire-based tunable Josephson junction; including single charges, multiple charges, and Cooper pairs. We studied all the charge tunneling processes using Landau-Zener-Stückelberg-Majorana (LZSM) interferometry, and observed high-quality interference patterns under a microwave drive. In particular, the coherence time of the charge states tunneling back and forth was extracted from the interference fringes in Fourier space. In addition, our measurements show the break-up of Cooper pairs, from a macroscopic quantum coherent state to individual particle states. Besides the fundamental research interest, our results also establish LZSM interferometry as a powerful technique to explore the coherence time of charges in hybrid devices.



中文翻译:

量化可调约瑟夫森结中多电荷态的量子相干性

相干性和隧道效应在量子现象中发挥着核心作用。在隧道事件中,粒子在势垒内停留的时间一直存在激烈争论。当隧道效应来回反复​​发生并且涉及许多粒子时,这个问题会变得更加复杂。在这里,我们报告了基于纳米线的可调谐约瑟夫森结中各种电荷态隧道的相干时间的测量;包括单电荷、多电荷和库珀对。我们使用 Landau-Zener-Stückelberg-Majorana (LZSM) 干涉仪研究了所有电荷隧道过程,并在微波驱动下观察到了高质量的干涉图案。特别是,从傅立叶空间中的干涉条纹中提取来回隧道传输的电荷态的相干时间。此外,我们的测量显示了库珀对的分裂,从宏观量子相干态到单个粒子态。除了基础研究兴趣之外,我们的研究结果还确立了 LZSM 干涉测量作为探索混合器件中电荷相干时间的强大技术。

更新日期:2024-01-02
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