  We propose an approach to quantum phase estimation that can attain precision
near the Heisenberg limit without requiring single-particle-resolved state
detection. We show that the "one-axis twisting" interaction, well known for
generating spin squeezing in atomic ensembles, can also amplify the output
signal of an entanglement-enhanced interferometer to facilitate readout.
Applying this interaction-based readout to oversqueezed, non-Gaussian states
yields a Heisenberg scaling in phase sensitivity, which persists in the
presence of detection noise as large as the quantum projection noise of an
unentangled ensemble. Even in dissipative implementations -- e.g., employing
light-mediated interactions in an optical cavity or Rydberg dressing -- the
method significantly relaxes the detection resolution required for spectroscopy
beyond the standard quantum limit.
