Physics. So small yet still giant.
Physics. So small yet still giant.
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物理。
DOI：
10.1126/science.1141972
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Lerner IV
中科院分区：
文献类型：
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作者：
Lerner IV
尽管电子设备不断缩小到原子的纳米尺度，但物理学家仍然要处理多粒子系统，在这些系统中，追踪单个粒子的路径超出了理论和实验的范围。因此，我们必须依靠统计方法。从19世纪统计物理学继承下来的传统观点认为，对给定样品的物理测量可以通过对相同样品的集合进行平均来很好地描述。然而，随着可重现电导波动的预测，这一概念在20多年前就过时了（即，从样品到样品的变化）在“介观”结构与原子和散装物质（1，2）之间的尺寸中间。这些涨落并不随样本大小而减小（在经典物理学中应该如此），但仍然比平均电导小得多。在第99页的这个问题，价格等。(3)报告了在非常低的温度下观察到的双层系统中的库仑阻力（4），其中阻力的可再现波动比其平均值大得多。因此，作者发现了介观涨落，与电导涨落相反，完全控制效应而不是对其进行校正-这在统计物理学中是非常不寻常的情况。在进行这项工作的过程中，他们开发了一种新的工具来研究固体中电子的波动行为。
Although electronic devices keep shrink-ing toward the nanometer scale of atoms, physicists still deal with many-particle systems in which tracing the paths of individual particles is beyond the reach of theory and experiment. Because of this, we have to rely on a statistical approach. Conventional wisdom, inherited from 19thcentury statistical physics, says that physical measurements on a given sample are well described by averaging over an ensemble of identical samples.This notion became obsolete more than two decades ago, however, with the prediction of reproducible conductance fluctuations (ie, variations from sample to sample) in “mesoscopic” structures with dimensions intermediate between atoms and bulk matter (1, 2). These fluctuations do not decrease with sample size (as they should in classical physics) but still remain much smaller than the average conductance. On page 99 of this issue, Price et al.(3) report the observation of the Coulomb drag (4) in a bilayer system at very low temperatures where the reproducible fluctuations of the drag turn out to be much larger than its average value. Thus, the authors have discovered mesoscopic fluctuations that, in contrast to the conductance fluctuations, fully govern the effect rather than give corrections to it—a very unusual situation in statistical physics. In carrying out this work, they have developed a new tool for studying the wave-like behavior of electrons in solids.