  Squeezing of the electromagnetic vacuum is an essential metrological
technique used to reduce quantum noise in applications spanning gravitational
wave detection, biological microscopy, and quantum information science. In
superconducting circuits, the resonator-based Josephson-junction parametric
amplifiers conventionally used to generate squeezed microwaves are constrained
by a narrow bandwidth and low dynamic range. In this work, we develop a
dual-pump, broadband Josephson traveling-wave parametric amplifier that
combines a phase-sensitive extinction ratio of 56 dB with single-mode squeezing
on par with the best resonator-based squeezers. We also demonstrate two-mode
squeezing at microwave frequencies with bandwidth in the gigahertz range that
is almost two orders of magnitude wider than that of contemporary
resonator-based squeezers. Our amplifier is capable of simultaneously creating
entangled microwave photon pairs with large frequency separation, with
potential applications including high-fidelity qubit readout, quantum
illumination and teleportation.
