Picosecond Response of a Quantum Point Contact

Extensive studies of electronic transport in the quantum regime have led to a deep understanding of the near-zero frequency conductance of mesoscopic structures. In contrast, our understanding of the high frequency response is much less well developed, due partially to the comparative lack of experimental results. We have developed a novel technique for probing the high-frequency properties of the simplest of mesoscopic structures, the quantum point contact (QPC) [l]. The technique can be extended to other mesoscopic devices and measurements on quantum dots are in-progress.