Introduction to Quantum-limited Parametric Amplification of Quantum Signals with Josephson Circuits

摘要

This short and opinionated review starts with a concept of quantum signals atmicrowave frequencies and focuses on the principle of linear parametricamplification. The amplification process arises from the dispersivenonlinearity of Josephson junctions driven with appropriate tones. We discusstwo defining characteristics of these amplifiers: the number of modes receivingthe signal, idler and pump waves and the number of independent ports throughwhich these waves enter into the circuit.