AI 中文总结
本研究通过毫开尔文温度下扫描隧道显微镜的可调隧穿结，连续调控约瑟夫森能与充电能的比值，在单个约瑟夫森结中观测到库珀对流动从非相干到相干的平滑过渡，揭示了可控的量子-经典过渡。
AI 中文摘要
量子力学限制共轭可观测量无法同时以任意精度测量，在约瑟夫森结中，这两个量为转移电荷与超导域间的量子力学相位差。二者的波动状态决定超电流：一种极限下是单库珀对的耗散性涓流，另一种极限下是相干无耗散流动。由于约瑟夫森能与充电能在器件制备时固定，在单一器件中桥接两种状态的尝试一直未获成功。本研究使用毫开尔文温度下扫描隧道显微镜的可调隧穿结，将二者的比值在多个数量级上连续调控，由此在单个结中观测到非相干到相干库珀对流动的平滑过渡，以可控方式揭示了量子-经典过渡。
英文摘要
Quantum mechanics constrains conjugate observables from being simultaneously measurable with arbitrary precision. In a Josephson junction, these are the transferred electric charge and the quantum-mechanical phase difference between the superconducting domains. Which of them fluctuates determines the supercurrent: a dissipative trickle of single Cooper pairs in one limit, a coherent dissipationless flow in the other. Bridging both regimes in one device remained elusive because the Josephson and charging energies are fixed at fabrication. Here, we use the tunable tunnel junction of a scanning tunneling microscope at millikelvin temperature to vary their ratio continuously over many orders of magnitude. In this way, we monitor the smooth transition between incoherent and coherent Cooper pair flow in a single junction, revealing the quantum-to-classical transition in a controlled way.
Comments16 pages, 5 figures, including supplementary information
