论文标题
库珀对产生的纳米力学振动的抽水和冷却
Pumping and cooling of nanomechanical vibrations generated by Cooper pair exchange
论文作者
论文摘要
我们考虑了一种纳米机电系统，该系统由碳纳米管组成，该系统悬浮在两个正常导线之间，并通过真空隧道屏障耦合到超导扫描隧道显微镜（STM）尖端。将纳米管视为单层量子点，这表明超导STM尖端和正常铅之间的施加电压会导致机械子系统的泵送或冷却，这取决于电子流的方向。还证明，这两个方案之间的过渡受纳米管与超导STM尖端之间的隧道耦合的强度以及电子水平的相对位置的控制。由于特定的机电耦合，这种现象是由库珀对的量子动力学完全控制的。通过数值分析泵送方案中自我维持的振荡的幅度，并获得了冷却方案中机械子系统的有效温度。
We consider a nanoelectromechanical system composed of a carbon nanotube suspended between two normal leads and coupled to a superconducting scanning tunneling microscope (STM) tip via vacuum tunnel barrier. Treating the nanotube as a single-level quantum dot, it is shown that an applied voltage between the superconducting STM tip and normal leads gives rise to a pumping or a cooling of the mechanical subsystem depending on the direction of the electronic flow. It is also demonstrated that the transition between these two regimes is controlled by the strength of the tunnel coupling between the nanotube and superconducting STM tip and the relative position of the electronic level. Such phenomena are realized due to a specific electromechanical coupling that is fully governed by the quantum dynamics of the Cooper pairs. The amplitude of the self-sustained oscillations in the pumping regime is analyzed numerically, and the effective temperature of the mechanical subsystem in the cooling regime is obtained.
