Low-Noise Current Amplifier Based on Mesoscopic Josephson Junction
J. Delahaye,1*
J. Hassel,2
R. Lindell,1
M. Sillanpää,1
M. Paalanen,1
H. Seppä,2
P. Hakonen1
We used the band structure of a mesoscopic Josephson junction to
construct low-noise amplifiers. By taking advantage of the quantum
dynamics of a Josephson junction, i.e., the interplay of interlevel
transitions and the Coulomb blockade of Cooper pairs, we created
transistor-like devices, Bloch oscillating transistors, with
considerable current gain and high-input impedance. In these transistors, the correlated supercurrent of Cooper pairs is controlled by a small base current made up of single electrons. Our devices reached current and power gains on the order of 30 and 5, respectively. The noise temperature was estimated to be around 1 kelvin, but noise
temperatures of less than 0.1 kelvin can be realistically achieved.
These devices provide quantum-electronic building blocks that will be
useful at low temperatures in low-noise circuit applications with an
intermediate impedance level.
1 Low Temperature Laboratory, Helsinki
University of Technology, Post Office Box 2200, 02015 HUT, Finland.
2 Microsensing, VTT Information Technology,
Post Office Box 1207, 02044 VTT, Finland.
*
Present address: High Magnetic Field Laboratory, LCMI/CNRS BP
166, F-38042 Grenoble, France.
To whom correspondence should be addressed. E-mail:
pertti.hakonen{at}hut.fi
