Nanomechanics and Nanoelectronics for Measurements near Quantum Limits

新技术使研究人员能够制造尺寸只有几十纳米（数百个原子）大小的可移动结构，称为纳米机械设备。这些可以形成具有前所未有的灵敏度的新传感器，例如检测单个原子产生的磁力的显微镜。为了达到某些应用所需的灵敏度，这些设备实际上几乎与灵敏度的极限一样灵敏。量子力学--支配原子和分子行为的物理定律--告诉我们，对纳米机械设备的运动进行测量必须改变运动。这种“反作用”最终必然会限制我们测量的灵敏度。罗伯特·诺贝尔和他的学生和同事团队正在努力制造非常接近这一极限的纳米机械设备。他们通过对耦合系统进行仔细的电学测量，通过将整个系统冷却到接近绝对零度，通过用单原子厚度的材料制造力学系统来做到这一点。这项研究的结果在两个方面很有用：首先，我们想了解力学测量的极限是什么。为了让我们的设备像理论物理学家预测的那样工作，我们必须做些什么？其次，制造如此敏感的设备可以实现新的现实应用。检测单个原子产生的磁力可以完美地重建蛋白质，从而实现药物发现和诊断。

New technology has enabled researchers to make movable structures with dimensions only tens of nanometers (hundreds of atoms) in size, called nanomechanical devices. These can form new sensors with unprecedented sensitivity, such as microscopes that detect the magnetic force due a single atom.To reach the sensitivity needed for some applications, the devices are actually almost as sensitive the ultimate limit of sensitivity. Quantum mechanics - the physical laws that govern the behaviour of atoms and molecules - tells us that making a measurement of the motion of a nanomechanical device must change the motion. This "back-action" must ultimately limit how sensitive our measurement can be.Robert Knobel and his team of students and colleagues are working to make nanomechanical devices that are very close to this limit. They do this by making careful electrical measurements of coupled systems, by cooling down the whole system to nearly absolute zero, by making the mechanical systems out of single-atom-thick material.The outcome of this research is useful in two ways: first we want to understand what the limits of mechanical measurement are. What do we have to do in order to have our devices work as well as theoretical physicists predict? Second, making a device this sensitive could enable new real-world applications. Detecting the magnetic force due to a single atom could allow perfect reconstruction of, for instance, a protein, enabling drug discovery and diagnosis.