0000000000505254
AUTHOR
Marko T. Savolainen
Microwave induced co-tunneling in single electron tunneling transistors
Abstract The influence of microwaves on the co-tunneling in single electron tunneling transistors has been investigated as function of frequency and power in the temperature range from 150 to 500 mK. All 20 low frequency connections and the RF line were filtered, and the whole cryostat was suspended on rubber bellows. Cross-talk was minimized by using individual coaxial lines between the sample and the room temperature electronics. The co-tunneling experiments were performed at zero DC bias current by measuring the voltage response to a very small amplitude 2 Hz current modulation with the gate voltage fixed at maximum Coulomb blockade. With the microwave signal applied to one side of the t…
Experimental Investigation of Microwave Enhanced Cotunneling in SET Transistors
Cotunneling is an important error process in the application of single electron tunneling devices for metrological and electronic applications. Here we present an experimental investigation of the theory for adiabatic enhancement of cotunneling by coherent microwaves. The dependence is investigated as function of temperature, gate voltage, frequency, and applied microwave power. At low temperatures and applied power levels, the results are consistent with theory, using only the unknown damping in the microwave line as a free parameter. However, the results indicate that the effects of temperature, frequency and microwave power are not independent, contrary to what is suggested by theory.
Noise and Microwave Properties of Set-Transistors
Electron tunneling through a small tunnel junction with capacitance C 0 is suppressed by the so-called Coulomb blockade if the charging energy E c = e 2/2C∑ is larger than the thermal energy k B T 1. This effect is observed in a single electron tunneling transistor (SETT), which is a nano-meter size three-terminal device in which two leads connect to a small metallic island through two tunnel junctions. The excess charge on the island is regulated by the potential of the capacitively coupled gate electrode. The SETT is a very sensitive electrometer, noise levels of 10−5e/√Hz have been reached.2,3 A similar device, the electron pump, is made by connecting two or more islands in series throug…
Characterisation of Cooper Pair Boxes for Quantum Bits
We have fabricated and measured single Cooper pair boxes (SCB) using superconducting single electron transistors (SET) as electrometers. The box storage performance for Cooper pairs was measured by observing the changes in the SCB island potential. We are also fabricating niobium structures, which are expected to have less problems with quasiparticle contamination than similar aluminium based devices because of the high critical temperature. The use of niobium may also reduce decoherence and thereby increase the time available for quantum logic operations.