Low Temperature Laboratory (OVLL), Aalto University School of Science, P.O. Box 13500, 00076 Aalto, Finland and Centre for Metrology and Accreditation (MIKES), P.O. Box 9, 02151 Espoo, Finland.
Phys Rev Lett. 2013 Oct 4;111(14):147001. doi: 10.1103/PhysRevLett.111.147001. Epub 2013 Oct 3.
We investigate the dynamics of individual quasiparticle excitations on a small superconducting aluminum island connected to normal metallic leads by tunnel junctions. We find the island to be free of excitations within the measurement resolution. This allows us to show that the residual heating, which typically limits experiments on superconductors, has an ultralow value of less than 0.1 aW. By injecting electrons with a periodic gate voltage, we probe electron-phonon interaction and relaxation down to a single quasiparticle excitation pair, with a measured recombination rate of 16 kHz. Our experiment yields a strong test of BCS theory in aluminum as the results are consistent with it without free parameters.
我们研究了通过隧道结连接到正常金属引线的小型超导铝岛上单个准粒子激发的动力学。我们发现，在测量分辨率内，岛上没有激发。这使我们能够证明，通常会限制超导实验的剩余加热具有低于 0.1 aW 的超低值。通过周期性栅极电压注入电子，我们探测电子-声子相互作用和弛豫，直至达到单个准粒子激发对，测量到的复合速率为 16 kHz。我们的实验对铝中的 BCS 理论进行了强有力的检验，因为结果与其一致，没有自由参数。
