Pertti Hakonen

Mobility fluctuations have been observed to influence 1/f noise in mesoscopic two-dimensional conductors in recent experiments. If such mobility noise can be assigned to clustering/declustering of defects/impurities, the second spectrum should also display 1/f character. In this work, we investigate the second spectrum of noise due to mobile impurities on a two-dimensional lattice both using kinetic Monte Carlo simulations (periodic boundary conditions either in one or two directions) and experiments on suspended graphene in Corbino geometry. The simulations indicate 1/fδ behavior with δ≃0.8 ± 0.15 for the second spectrum of noise, while the experiments on suspended graphene yield an exponent δ≃0.7 ± 0.3, independent of the amount of adsorbed atoms.

From the background of microwave‐optomechanical experiments involving carbon nanotubes, the optimization of superconducting coplanar waveguide resonator devices is discussed. Two devices, one with unmodified geometry compared to previous work and one integrating several improvements, are lithographically built up step‐by‐step. After each step, the low‐temperature GHz transmission properties are retested. This allows to identify the impact of the fabrication and the geometry modification on the device properties. In addition, simplified circuit geometries are modeled numerically, confirming the experimental results and providing further insights for optimization.