两个物理学实验上的进展


利用压缩光,LIGO的科学家使得引力波探测器的灵敏度增加了44%。这是压缩光在引力波探测中有效性的首次测试。在未来1-3年内,这个技术将在实际的 引力波探测器LIGO中应用。LIGO探测器中的光损耗将更小,因此预计探测器灵敏度将会增加更多。科学家预测,灵敏度增大200%将使人们可能看到引力 波。
physicswebnature physics

最近我正在做的一个题目是关于产生压缩光的新方案。现有的压缩光产生都需要非线性晶体,压缩直接与晶体的好坏有关。由于系统比较复杂,非线性晶体 的非线性较弱等各种限制,最近才制备出了10dB的压缩光,也就是噪声被压缩到了真空噪声的1/10。我们讨论的这个方案不需要非线性晶体,系统也大大简 化了。我希望这个工作能够帮助制备压缩度更大的压缩光,比如噪声只是真空噪声的1/100,以便人们观测到引力波。

200K的高温超导体?

http://arxiv.org/abs/0804.0824
Title: Evidence for High Tc Superconducting Transitions in Isolated Al45- and Al47- Nanoclusters
Authors: Baopeng Cao, Colleen M. Neal, Anne K. Starace, Yurii N. Ovchinnikov, Vladimir Z. Kresin, Martin F. Jarrold

Abstract: Heat capacities measured for Al45- and Al47- nanoclusters have reproducible jumps at ~ 200 K. These jumps are consistent with theoretical predictions that some clusters with highly degenerate electronic states near the Fermi level will undergo a transition into a high Tc superconducting state. An analysis based on a theoretical treatment of pairing in Al45- and Al47- agrees well with the experimental data in both the value of the critical temperature and in the size and width of the jumps in the heat capacity.

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