| This thesis consists primarily of the description of two single-electron circuits that I fabricated and measured utilizing radio-frequency techniques. A short summary of the background material necessary for understanding this area of condensed matter experiment is included as well as a discussion of the utility of these devices as charge-sensing or energy-sensing circuit elements.; In the first measurement, by configuring a radio-frequency single-electron transistor as a mixer, we demonstrate a unique implementation of this device, that achieves good charge sensitivity with large bandwidth about a tunable center frequency. In our implementation we achieve a measurement bandwidth of 16 MHz, with a tunable center frequency from 0 to 1.2 GHz, demonstrated with the transistor operating at 300 mK. Ultimately this device is limited in center frequency by the RC time of the transistor's center island, which for our device is ∼1.6 GHz, close to the measured value. The measurement bandwidth is determined by the quality factor of the readout tank circuit.; In the second measurement, we detect the energy-selective diffusion of electrons through a tunnel junction to perform a new type of passive, low-power dissipation thermometry. The thermometer is based on a novel, three-junction single electron transistor, which is made with a superconducting nanoscale metal island, coupled to two tunnel junctions and a capacitive gate in the standard single-electron transistor configuration, and in addition a third tunnel junction couples the transistor island to a normal metal thin-film volume, which serves as a calorimeter. Passive diffusion of electrons from the calorimeter through the third junction changes the transistor conductance, providing a thermometric signal. This device dissipates minimal power in the calorimeter, removing a stringent limit on the minimum temperatures and energy sensitivities achievable in nanoscale calorimeters and bolometers. High speed measurements were made possible by embedding the transistor in a radiofrequency impedance-matching circuit, and heat could be applied to the calorimeter in nanosecond to millisecond pulses. Measured and simulated results are presented, and potential applications to minimal back-action calorimeters and bolometers are discussed. |
