Near-quantum-limited subgigahertz Ti N kinetic inductance traveling-wave parametric amplifier operating in a frequency-translating mode

We present the design and experimental characterization of a kinetic inductance traveling-wave parametric amplifier (KI-TWPA) for subgigahertz frequencies. KI-TWPAs amplify signals through mixing processes supported by the nonlinear kinetic inductance of a superconducting transmission line. The device described here uses a compactly meandered TiN microstrip transmission line to achieve the length needed to amplify subgigahertz signals. It is operated in a frequency-translating mode where the amplified signal tone is terminated at the output of the amplifier, and the idler tone at approximately 2.5 GHz is brought out of the cryostat. By varying the pump frequency, a gain of up to 22 dB was achieved in a tunable range from about 450 to 850 MHz. Using TiN as the nonlinear element allows for a reduction of the required pump power by roughly an order of magnitude relative to NbTiN, which has been used for previous KI-TWPA implementations. This amplifier has the potential to enable high-sensitivity and high-speed measurements in a wide range of applications, such as quantum computing, astrophysics, and dark matter detection.