Improved microwave SQUID multiplexer readout using a kinetic-inductance traveling-wave parametric amplifier

We report on the use of a kinetic-inductance traveling-wave parametric amplifier (KITWPA) as first in readout chain microwave superconducting quantum interference device (SQUID) multiplexer (umux). This umux is designed to multiplex signals from arrays low temperature detectors such transition-edge sensor microcalorimeters. When modulated with periodic flux-ramp linearize SQUID response, flux noise improves, average, $1.6$ $\mu\Phi_0/\sqrt{\mathrm{Hz}}$ KITWPA off, $0.77$ on. statically biasing maximally flux-sensitive point, drops $0.45$ $0.2$ $\mu\Phi_0/\sqrt{\mathrm{Hz}}$. validate this new scheme by coupling microcalorimeter and detecting background radiation. The combination provides variety capabilities including improved detector sensitivity more efficient bandwidth utilization.