Spin-dependent collision of ultracold metastable atoms

Spin-polarizedmetastable atoms of ultracold ytterbium are trapped at high density and their inelastic collisional properties are measured. We reveal that in collisions of Yb(P2) with Yb(S0) there is relatively weak inelastic loss, but with a significant spin dependence consistent with Zeeman sublevel changes as being the dominant decay process. This is in strong contrast to our observations of Yb(P2)–Yb(P2) collisional losses, which are, at low field, much more rapid and have essentially no spin dependence. Our results give a guideline to using the P2 states in many possible applications.