Perspective on traveling wave microwave parametric amplifiers

Quantum-limited microwave parametric amplifiers are genuine key pillars for rising quantum technologies and in general applications that rely on the successful readout of weak signals by adding only minimum amount noise allowed mechanics. In this perspective, after providing a brief overview different families amplifiers, we focus traveling wave (TWPAs), underlining achievements last years present open challenges. We discuss also possible new research directions beyond amplification such as exploring these devices platform multi-mode entanglement generation development single photon detectors.