The Radio-frequency single electron transistor (RF-SET) is the fastest and most sensitive electrometer known today. Many schemes proposed for sensitive measurement applications have invoked the promise of the RF-SET for fast and ultra-sensitive charge detection. These include Qubits based on nuclear spins in silicon, charged particle detectors, quantum nanomechanical oscillations and single terahertz photon counters. It is one of the only tools for detecting single electron charges at the nanometer scale and with gigahertz band-width.

In collaboration with the Chalmers and Yale groups, we have made theoretical analysis and experiments to estimate the charge sensitivity of a radio frequency single-electron transistor. The theoretical prediction is based on a model which includes equivalent circuits for all the components of the measurement system. Low-noise first-stage amplifier was integrated in the analysis and the noise power wave formalism was employed in the analysis of the aluminum single-electron transistor test system.

The analyzed measurement setup. a) A carrier wave is guided down to the SET using the RF IN line. An attenuator of 30 dB and a directional coupler with 13 dB loss attenuate thermal noise. The wave is reflected from the SET with an LC matching circuit and amplified with a chain of cold and warm amplifiers. The signal is detected from RF OUT port using a diode detector. b) Noise measurement schematic.
The fraction of available power coupled to the load (K) and to the coupling network (N), as well as the reflection coefficient Γ. For our Al-SET, the dashed lines limit the range of RFSET that is usable for finding the optimum operating conditions.

Related publications

  • Noise performance of the radio-frequency single-electron transistor

L. Roschier, P.J. Hakonen, K. Bladh, P. Delsing, K.W. Lehnert, L. Spietz, and R.J. Schoelkopf

J. Appl. Phys. 95, 1274 (2004)