  Microwave squeezing represents the ultimate sensitivity frontier for
superconducting qubit measurement. However, observation of enhancement has
remained elusive, in part because integration with conventional dispersive
readout pollutes the signal channel with antisqueezed vacuum. Here we induce a
stroboscopic light-matter coupling with superior squeezing compatibility, and
observe an increase in the room-temperature signal-to-noise ratio of 24%.
Squeezing the orthogonal phase controls measurement backaction, slowing
dephasing by a factor of 1.8. This protocol enables the practical use of
microwave squeezing for qubit state measurement.
