title: Josephson junction microwave amplifier in self-organized noise compression mode.
abstract: The fundamental noise limit of a phase-preserving amplifier at frequency [Formula: see text] is the standard quantum limit [Formula: see text]. In the microwave range, the best candidates have been amplifiers based on superconducting quantum interference devices (reaching the noise temperature [Formula: see text] at 700 MHz), and non-degenerate parametric amplifiers (reaching noise levels close to the quantum limit [Formula: see text] 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, [Formula: see text] 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.
authors.forename: Pasi
authors.initials: P
authors.lastname: Lähteenmäki
authors.forename: Visa
authors.initials: V
authors.lastname: Vesterinen
authors.forename: Juha
authors.initials: J
authors.lastname: Hassel
authors.forename: Heikki
authors.initials: H
authors.lastname: Seppä
authors.forename: Pertti
authors.initials: P
authors.lastname: Hakonen