  We report simultaneous measurement of shot noise and dc transport in a
quantum point contact as a function of source-drain bias, gate voltage, and
in-plane magnetic field. Shot noise at zero field exhibits an asymmetry related
to the 0.7 structure in conductance. The asymmetry in noise evolves smoothly
into the symmetric signature of spin-resolved electron transmission at high
field. Comparison to a phenomenological model with density-dependent level
splitting yields good quantitative agreement.
