Vacuum and Two-mode Squeezing Using Superconducting Kinetic Inductance Traveling Wave Parametric Amplifiers.

Superconducting parametric amplifiers operating in the phase-sensitive regime are well-known for their ability to generate correlated photon pairs via the process of two-mode squeezing. These correlated states are increasingly attractive for quantum information science and sensing. In some scenarios, such as light dark matter (axion and hidden photon) searches, entangled photon states and beyond-quantum-limit detection schemes are likely to become mandatory metrological resources and practices. Traveling wave parametric amplifiers (TWPAs) – using the nonlinear kinetic inductance of the disordered superconductor NbTiN – are a promising avenue to fulfill these requirements while also achieving a wide-bandwidth, high-output-power, and magnetic-field-resilient device. Our TWPAs are created from a dispersion-engineered, stub-loaded inverted NbTiN microstrip and, in the phase-insensitive regime, have shown high gain (>20 dB true gain), beyond-octave gain bandwidths (4.5–10 GHz), and added noise (2.5 quanta) near the quantum limit . Here we investigate the performance of our kinetic inductance TWPAs as phase-sensitive amplifiers via measurements of the level and bandwidth of both vacuum and two-mode squeezing. These results advance our understanding of the internal loss of these devices, and establish their utility in applications that seek to realize broadband quantum evasion, or quantum illumination with gigahertz bandwidth and high output compression power (-50 dBm).