2010年4月7日
Carbon nanotubes, long touted for applications in materials and electronics, may also be the stuff of atomic-scale black holes.
发射的激光冷却原子被一个悬挂的单壁碳纳米管捕获，收取数百伏。捕获的原子朝向纳米管（白色路径），并到达管表面的周围，其价电子（黄色）隧道进入管子。弹出并检测到所得的离子（紫色），并敏感地探测了纳米级的动力学。
Physicists at Harvard University have found that a high-voltage nanotube can cause cold atoms to spiral inward under dramatic acceleration before disintegrating violently. Their experiments, the first to demonstrate something akin to a black hole at atomic scale, are described in the current issue of the journal Physical Review Letters.
"On a scale of nanometers, we create an inexorable and destructive pull similar to what black holes exert on matter at cosmic scales," says Lene Vestergaard Hau, Mallinckrodt Professor of Physics and of Applied Physics at Harvard. "As importantly for scientists, this is the first merging of cold-atom and nanoscale science, and it opens the door to a new generation of cold atom experiments and nanoscale devices."
Hau and co-authors Anne Goodsell, Trygve Ristroph, and Jene A. Golovchenko laser-cooled clouds of one million rubidium atoms to just a fraction of a degree above absolute zero. The physicists then launched this millimeter-long atomic cloud towards a suspended carbon nanotube, located some two centimeters away and charged to hundreds of volts.
绝大多数原子通过电线经过，但是那些在它的微米之内的原子（每百万个原子云中大约有10个原子）被不可避免地吸引，当它们朝纳米管螺旋式时，它们达到了高速。
“从每秒大约5米开始，冷原子的速度达到每秒大约1200米，或每小时超过2,700英里，它们圈出纳米管的速度，”该项目的研究生Goodsell说，现在是该项目的研究生哈佛大学物理学博士研究员。“作为这种巨大加速的一部分，对应于原子的动能的温度从小于微秒的情况下从0.1度开尔文增加到了数千度开尔文。”
At this point, the speeding atoms separate into an electron and an ion rotating in parallel around the nanowire, completing each orbit in just a few trillionths of a second. The electron eventually gets sucked into the nanotube via quantum tunneling, causing its companion ion to shoot away -- repelled by the strong charge of the 300-volt nanotube -- at a speed of roughly 26 kilometers per second, or 59,000 miles per hour.
The entire experiment was conducted with great precision, allowing the scientists unprecedented access to both cold-atom and nanoscale processes.
Rumford物理学教授兼哈佛大学Gordon M欧洲杯线上买球cKay Applied Physics教授Golovchenko说：“冷原子和纳米级科学各自为研究和应用提供了令人兴奋的新系统。”“这是冷原子纳米结构系统的第一个实验实现。我们的系统表现出纳米级的原子，电子和离子动力学的敏感探测。”
这些研究人员成功实验中使用的单壁碳纳米管被称为“露西”，其贡献在《物理审查信》论文中得到了认可。纳米管是通过化学蒸气沉积在硅芯片中的10微米间隙中生长的，该硅芯片可为纳米线提供机械支撑和电气接触。
豪说：“从原子的角度来看，纳米管是无限长而薄的，对原子产生了奇异的效果。”
来源：http://www.harvard.edu/