4 research outputs found
Josephson Amplifier for Qubit Readout
We report on measurements of a Josephson amplifier (J-amp) suitable for
quantum-state qubit readout in the microwave domain. It consists of two
microstrip resonators which intersect at a Josephson ring modulator. A maximum
gain of about 20 dB, a bandwidth of 9 MHz, and a center-frequency tunability of
about 60 MHz with gain in excess of 10 dB have been attained for idler and
signal of frequencies 6.4 GHz and 8.1 GHz, in accordance with theory. Maximum
input power measurements of the J-amp show a relatively good agreement with
theoretical prediction. We discuss how the amplifier characteristics can be
improved.Comment: 9 pages, 4 figure