  High Q phase gradient metasurfaces are becoming promising elements for
revolutionizing light manipulation but near-field coupling typically forces a
trade-off between quality factor and resolution. Here, we show a strategy for
not just reducing but eliminating coupling-based nonlocal effects in wave
shaping metasurfaces composed of meta-pixels with arbitrarily high Q arranged
with sub-diffraction spatial resolution. By working at a zero-coupling regime
introduced by the interference between enhanced longitudinal and transverse
electric fields, the tradeoff between Q and resolution no longer exists.
Exploiting for wave shaping the ability to fully suppress coupling between high
Q meta-atoms, we numerically show structurally uniform devices that produce
beam-splitting to angles of $\pm53^o$ and beam-steering to an angle of $33^o$
with diffraction efficiencies over 90% via refractive index bias of just
$2\times10^{-6}$ and $7\times10^{-6}$, respectively. These are made possible by
the meta-structure supporting local dipole resonances with Qs of 2.8 million
and 0.87 million respectively, arranged with a dense pixel pitch of
${\lambda}/1.6$. Extending the approach to structures with ${\lambda}/2.2$
resolution we also unlock full-field beam steering via index biasing of just
$1\times10^{-4}$. The signature of a zero-coupling regime is discovered in the
form of a sign flip in the angular dispersion with resonant wavelength in
experiment which validates our scheme. Aside from triangulating a perfect
decoupling configuration, one of our fabricated nanofin-isolated metasurfaces
with Q-factor >870 has a resonant wavelength that stays within the half
linewidth for incident angles of $-20^o$ to $20^o$. Our platform provides a
route for densely arrayed high Q metasurfaces with independently addressable
constituent meta-atoms, paving the way for highly efficient nonlinear and
dynamic wavefront shaping.
