Direct measurement of the maximum tunnel rate in a radio frequency single electron transistor operated as a microwave mixer

TL;DR

This paper demonstrates a method to measure the maximum tunnel rate of a radio frequency single electron transistor (rf-SET) by operating it as a microwave mixer, revealing its high-frequency response and potential for sensing signals beyond its bandwidth.

Contribution

The study introduces a novel technique using the non-linear transconductance of rf-SET as a mixer to measure tunnel rates at microwave frequencies, surpassing previous bandwidth limitations.

Findings

The RC roll-off of the tunnel junctions is observed at frequencies above 15 GHz.

The induced charge on the rf-SET island changes faster than the inverse tunnel rate at high frequencies.

The technique suggests potential for sensing signals beyond the conventional rf-SET bandwidth.

Abstract

By operating the radio frequency single electron transistor (rf-SET) as a mixer we present measurements in which the RC roll-off of the tunnel junctions is observed at high frequencies. Our technique makes use of the non-linear rf-SET transconductance to mix high frequency gate signals and produce difference-frequency components that fall within the bandwidth of the rf-SET. At gate frequencies >15GHz the induced charge on the rf-SET island is altered on time-scales faster than the inverse tunnel rate, preventing mixer operation. We suggest the possibility of utilizing this technique to sense high frequency signals beyond the usual rf-SET bandwidth.