  We have observed sub-Poissonian spin correlations generated by collisionally
induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum
noise reduction of -7 dB (-10 dB corrected for detection noise) below the
standard quantum limit (SQL) for the corresponding coherent spin states. The
spin fluctuations are detected as atom number differences in the spin states
using fluorescent imaging that achieves a detection noise floor of 8 atoms per
spin component for a probe time of 100 $\mu$s.
