  The observation of gravitational waves from binary neutron star mergers
offers insights into properties of extreme nuclear matter. However, their
high-frequency signals in the kHz range are often masked by quantum noise of
the laser light used. Here, we propose the "quantum expander with coherent
feedback", a new detector design that features an additional optical cavity in
the detector output and an internal squeeze operation. This approach allows to
boost the sensitivity at high frequencies, at the same time providing a compact
and tunable design for signal extraction. It allows to tailor the sensitivity
of the detector to the specific signal frequency range. We demonstrate that our
design allows to improve the sensitivity of the high-frequency detector concept
NEMO (neutron star extreme matter observatory), increasing the detection rates
by around 15%. Our approach promises new level of flexibility in designing the
detectors aiming at high-frequency signals.
