Sci Rep. 2012;2:293. doi: 10.1038/srep00293. Epub 2012 Feb 29.
The smaller the system, typically - the higher is the impact of fluctuations. In narrow superconducting wires sufficiently close to the critical temperature T(c) thermal fluctuations are responsible for the experimentally observable finite resistance. Quite recently it became possible to fabricate sub-10 nm superconducting structures, where the finite resistivity was reported within the whole range of experimentally obtainable temperatures. The observation has been associated with quantum fluctuations capable to quench zero resistivity in superconducting nanowires even at temperatures T→0. Here we demonstrate that in tiny superconducting nanorings the same phenomenon is responsible for suppression of another basic attribute of superconductivity - persistent currents - dramatically affecting their magnitude, the period and the shape of the current-phase relation. The effect is of fundamental importance demonstrating the impact of quantum fluctuations on the ground state of a macroscopically coherent system, and should be taken into consideration in various nanoelectronic applications.
系统越小，波动的影响就越大。在接近临界温度 T(c) 的狭窄超导金属线中，热波动导致实验中可观测到的有限电阻。最近，人们已经能够制造出亚 10nm 的超导结构，在整个实验可获得的温度范围内，报道了有限的电阻率。这一观察结果与量子涨落有关，量子涨落即使在温度 T→0 时也能够在超导纳米线中消除零电阻。在这里，我们证明在微小的超导纳米环中，同样的现象导致了另一个超导基本属性——持续电流——的抑制，这显著影响了它们的大小、电流-相位关系的周期和形状。该效应具有重要的基础意义，证明了量子涨落对宏观相干系统基态的影响，在各种纳米电子应用中都应考虑到这一效应。
