Friedman JR, Patel V, Chen W, Tolpygo SK, Lukens JE
Department of Physics and Astronomy, The State University of New York, Stony Brook 11794-3800, USA.
Nature. 2000 Jul 6;406(6791):43-6. doi: 10.1038/35017505.
In 1935, Schrodinger attempted to demonstrate the limitations of quantum mechanics using a thought experiment in which a cat is put in a quantum superposition of alive and dead states. The idea remained an academic curiosity until the 1980s when it was proposed that, under suitable conditions, a macroscopic object with many microscopic degrees of freedom could behave quantum mechanically, provided that it was sufficiently decoupled from its environment. Although much progress has been made in demonstrating the macroscopic quantum behaviour of various systems such as superconductors, nanoscale magnets, laser-cooled trapped ions, photons in a microwave cavity and C60 molecules, there has been no experimental demonstration of a quantum superposition of truly macroscopically distinct states. Here we present experimental evidence that a superconducting quantum interference device (SQUID) can be put into a superposition of two magnetic-flux states: one corresponding to a few microamperes of current flowing clockwise, the other corresponding to the same amount of current flowing anticlockwise.
1935年，薛定谔试图通过一个思想实验来证明量子力学的局限性，在该实验中，一只猫被置于活态和死态的量子叠加态。直到20世纪80年代，这个想法一直只是学术上的好奇之事，当时有人提出，在合适的条件下，一个具有许多微观自由度的宏观物体可以表现出量子力学行为，前提是它与环境充分解耦。尽管在证明各种系统（如超导体、纳米级磁体、激光冷却的捕获离子、微波腔中的光子和C60分子）的宏观量子行为方面已经取得了很大进展，但尚未有实验证明真正宏观上不同状态的量子叠加。在此，我们展示了实验证据，即一个超导量子干涉器件（SQUID）可以被置于两种磁通量状态的叠加态：一种对应于几微安的电流顺时针流动，另一种对应于相同大小的电流逆时针流动。
