Deblock Richard, Onac Eugen, Gurevich Leonid, Kouwenhoven Leo P
Department of Nanoscience and ERATO Mesoscopic Correlation Project, Delft University of Technology, Post Office Box 5046, 2600 GA Delft, Netherlands.
Science. 2003 Jul 11;301(5630):203-6. doi: 10.1126/science.1084175.
The electrical noise of mesoscopic devices can be strongly influenced by the quantum motion of electrons. To probe this effect, we have measured the current fluctuations at high frequency (5 to 90 gigahertz) using a superconductor-insulator-superconductor tunnel junction as an on-chip spectrum analyzer. By coupling this frequency-resolved noise detector to a quantum device, we can measure the high-frequency, nonsymmetrized noise as demonstrated for a Josephson junction. The same scheme is used to detect the current fluctuations arising from coherent charge oscillations in a two-level system, a superconducting charge qubit. A narrow band peak is observed in the spectral noise density at the frequency of the coherent charge oscillations.
介观器件的电噪声会受到电子量子运动的强烈影响。为了探究这种效应，我们使用超导-绝缘体-超导隧道结作为片上频谱分析仪，测量了高频（5至90吉赫兹）下的电流涨落。通过将这种频率分辨噪声探测器与量子器件耦合，我们可以测量高频、非对称噪声，这在约瑟夫森结中得到了验证。同样的方案用于检测二能级系统（超导电荷量子比特）中相干电荷振荡产生的电流涨落。在相干电荷振荡频率处的频谱噪声密度中观察到一个窄带峰。
