Josephson junction microwave amplifier in self-organized noise compression mode

Abstract

The fundamental noise limit of a phase-preserving amplifier at frequency $\omega /2\pi$ is the standard quantum limit $T_q=\hslash \omega /2k_B$. In the microwave range, the best candidates have been amplifiers based on superconducting quantum interference devices (reaching the noise temperature $T_n\sim 1.8T_q$ at 700 MHz), and non-degenerate parametric amplifiers (reaching noise levels close to the quantum limit $T_n\approx T_q$ at 8 GHz). We introduce a new type of an amplifier based on the negative resistance of a selectively damped Josephson junction. Noise performance of our amplifier is limited by mixing of quantum noise from Josephson oscillation regime down to the signal frequency. Measurements yield nearly quantum-limited operation, $T_n=(3.2\pm 1.0)T_q$ at 2.8 GHz, owing to self-organization of the working point. Simulations describe the characteristics of our device well and indicate potential for wide bandwidth operation.

15 pages, 6 figures, supplementary information found in the published version

References in corpus (2)

• Amplification and squeezing of quantum noise with a tunable Josephson metamaterial
• Noise in resistively shunted Josephson junctions