Inelastic collisions of optically trapped metastable calcium atoms

Abstract

We study binary collisions of metastable calcium atoms ($^{40}$Ca) in an optical dipole trap. Collisions between $^{3}$P$_{0}$-atoms and between $^{3}$P$_{0}$ and $^{1}$S$_{0}$-atoms are considered. In the former case, the elastic and inelastic collision parameters are found to be $5.4\times 10^{-11}\,\mathrm{cm}^{3}\mathrm{s}^{-1}$ and $3.6\times 10^{-11}\,\mathrm{cm}^{3}\mathrm{s}^{-1}$, respectively. A fraction of the collisions between $^{3}$P$_{0}$-atoms is found to produce cold trapped atoms in the singlet $^{1}$S$_{0}$ state, suggesting that the internal energy for these collisions is dissipated by radiation. For collisions between $^{3}$P$_{0}$ and $^{1}$S$_{0}$-atoms we find a two-body loss parameter of $8.5\times 10^{-11}\,\mathrm{cm}^{3}\mathrm{s}^{-1}$. Our observations show that metastable calcium samples in the $^{3}$P$_{0}$-state are not stable at high densities, as for example required in quantum computing or many-body quantum simulation schemes.Comment: 5 pages, 7 Figure

Three-photon process for producing a degenerate gas of metastable alkaline-earth-metal atoms

“…However, it is reasonable to assume that the interaction broadening will be on the order of the ground state chemical potential, µ1 S 0 , and thus only weakly perturb the 3photon dynamics since the intermediate detunings are large. The inelastic collision rate for metastable AE atoms is on the order of 10 −10 − 10 −11 cm 3 /s depending on the state and species [24][25][26][27][28], while AE degenerate gases usually have densities 10 13 cm −3 [57,58]. We would thus expect the lifetime of the metastable degenerate gas to be limited to 10 ms, severely restricting the experimental timescale.…”

“…Inelastic collisional losses, which are on the order of 10 −10 − 10 −11 cm 3 /s, prevent direct evaporation of metastable AE atoms to quantum degeneracy [24][25][26][27][28]. Previous experiments used either incoherent excitation [24,26,28,29] or coherent excitation of a doubly-forbidden transition [27,30,31] to transfer pre-cooled AE atoms to a metastable state. These single-photon techniques necessarily impart momentum to the sample during excitation, which limits their application to either thermal atoms or to the Lamb-Dicke regime.…”

Suppression of two-body collisional losses in an ultracold gas via the Fano effect

“…With Eq. (9), we can analytically solve the Lippman-Schwinger equation (5) for the scattering state |Ψ (+) k l ,l , and thus obtain the s-wave scattering amplitude f jl (E s ) defined in Eq. (3) (Ref.…”

“…In ultracold gases of neutral atoms prepared in excited internal states (e.g., excited hyperfine states corresponding to the electronic ground level of alkali atoms or longlived excited states of alkali-earth (like) atoms), two-body collisional losses can be induced by inelastic scattering processes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In these processes the atoms can jump to the lower internal states and gain a large amount of kinetic energy.…”

Dissipative Bose-Hubbard system with intrinsic two-body loss

“…It is expected that similar behaviors will be observed with the 3 P 0 state of Yb [18,19] and other two-electron atomic species [13,14,17]. The strong suppression of the inelastic collision between atoms in the metastable state allows us to investigate the two-component manybody physics [30] and the manipulation of the 3 P 2 atoms exploiting the magnetic dipole moment [23], avoiding the atom loss in the practical time scale of the experiment.…”