Inelastic collisions of optically trapped metastable calcium atoms

We study binary collisions of metastable calcium atoms (Ca-40) in an optical dipole trap. Collisions between P-3(0) atoms and between P-3(0) and S-1(0) atoms are considered. In the former case, the elastic and inelastic collision parameters are found to be 5.4 x 10(-11) and 3.6 x 10(-11) cm(3) s(-1), respectively. A fraction of the collisions between P-3(0) atoms is found to produce cold trapped atoms in the singlet S-1(0) state, suggesting that the internal energy for these collisions is dissipated by radiation. For collisions between P-3(0) and S-1(0) atoms, we find a two-body loss parameter of 8.5 x 10(-11) cm(3) s(-1). Our observations show that metastable calcium samples in the P-3(0) state are not stable at high densities, which limits their usefulness in quantum computing or many-body quantum simulation schemes.