Detection of On-Chip Generated Weak Microwave Radiation Using Superconducting Normal-Metal SET

The present work addresses quantum interaction phenomena of microwave radiation with a single-electron tunneling system. For this study, an integrated circuit is implemented, combining on the same chip a Josephson junction (Al/AlO /Al) oscillator and a single-electron transistor (SET) with the superconducting island (Al) and normal-conducting leads (AuPd). The transistor is demonstrated to operate as a very sensitive photon detector, sensing down to a few tens of photons per second in the microwave frequency range around 100 GHz. On the other hand, the Josephson oscillator, realized as a two-junction SQUID and coupled to the detector via a coplanar transmission line (Al), is shown to provide a tunable source of microwave radiation: controllable variations in power or in frequency were accompanied by significant changes in the detector output, when applying magnetic flux or adjusting the voltage across the SQUID, respectively. It was also shown that the effect of substrate-mediated phonons, generated by our microwave source, on the detector output was negligibly small

Beruecksichtigung von Stellratenbegrenzern in Flugregelsystemen bei der Systembewertung im Frequenzbereich

Due to frequency domain analysis the describing function of a rate limiting element is derived using the Fourier transformation. A method is derived to calculate the describing function of the complete highly augmented aircraft system. The method is verified by a comparison with non-linear simulations in the time domain. The influence of rate limiting elements on handling qualities of augmented aircraft is discussed using five characteristic examples. The effects of rate saturation in the closed loop of the flight control system are presented by evaluations of the describing function in Nichols plots. Handling qualities evaluations using the Neal-Smith criterion show the effects of the rate limiters in the forward path of the flight control system on the tendency to pilot-induced oscillations. A new handling qualities criterion according to systems with rate saturation is proposed. (orig.)Available from TIB Hannover: RN 437(94-16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman