Alternative route to Bose-Einstein condensation of two-electron atoms

Abstract

We present a route to Bose-Einstein condensation devised for two-electron atoms, which do not admit practicable cooling techniques based upon narrow intercombination lines. A dipole trap for 40 Ca atoms in the singlet ground state is loaded from a moderately cold source of metastable triplet atoms via spatially and energetically selective optical pumping permitting 4 orders of magnitude increase of the phase-space density. Further cooling to quantum degeneracy is achieved by forced evaporation optimized to minimize three-body losses. In a combined loading and evaporation cycle of less than 3 s we are able to condense 3000 atoms.

Ultracold Fermi gases with emergent SU(N) symmetry

“…This was achieved in spite of the inelastic collisions associated with its large ground state s-wave scattering length (18nm < a s < 37nm) [58], by using a large volume optical trap for initial cooling. A second Calcium BEC was reported in 2012 by Hemmerich's group in Hamburg [69]. So far, no fermionic isotopes of Ca have have been cooled below the quantum degeneracy temperature.…”

Reservoir spectroscopy of5s5p3P2–5snStellmer1, Schreck2 2014Phys. Rev. A347441View full textAdd to dashboardCite

“…Quantum degenerate samples of Yb [7][8][9][10][11] and the alkaline-earth-metals Ca [12,13] and Sr [14][15][16][17][18][19][20] have opened new possibilities, such as the study of SU(N ) magnetism [21][22][23][24][25][26][27][28][29][30][31][32][33][34], novel schemes to simulate gauge fields [35][36][37][38][39][40], the engineering of interactions beyond contact interactions [41][42][43][44], the creation of driven-dissipative many-body states [45], the simulation of an extra dimension [46], and new ways to perform quantum computation [47][48][49][50][51].…”

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

“…We would thus expect the lifetime of the metastable degenerate gas to be limited to 10 ms, severely restricting the experimental timescale. However, several AE atom isotopes ( 40 Ca, 86 Sr, 168 Yb) have sufficiently strong interactions to allow cooling to degeneracy at relatively low densities ( 10 12 cm −3 ) [59][60][61]. These isotopes could also sympathetically cool other isotopes to degeneracy at low density.…”