B. J. DeSalvo

Degenerate Fermi gas of (87)Sr.

We report quantum degeneracy in a gas of ultracold fermionic (87)Sr atoms. By evaporatively cooling a mixture of spin states in an optical dipole trap for 10.5 s, we obtain samples well into the degenerate regime with T/T(F)=0.26(-0.06)(+0.05). The main signature of degeneracy is a change in the momentum distribution as measured by time-of-flight imaging, and we also observe a decrease in evaporation efficiency below T/T(F) ∼0.5.

Controlling Condensate Collapse and Expansion with an Optical Feshbach Resonance

We demonstrate control of the collapse and expansion of an (88)Sr Bose-Einstein condensate using an optical Feshbach resonance near the (1)S(0)-(3)P(1) intercombination transition at 689 nm. Significant changes in dynamics are caused by modifications of scattering length by up to ± 10a(bg), where the background scattering length of (88)Sr is a(bg) = -2a(0) (1a(0) = 0.053 nm). Changes in scattering length are monitored through changes in the size of the condensate after a time-of-flight measurement. Because the background scattering length is close to zero, blue detuning of the optical Feshbach resonance laser with respect to a photoassociative resonance leads to increased interaction energy and a faster condensate expansion, whereas red detuning triggers a collapse of the condensate. The results are modeled with the time-dependent nonlinear Gross-Pitaevskii equation.

Repumping and spectroscopy of laser-cooled Sr atoms using the (5s5p)3P2–(5s4d)3D2 transition

We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p)3P2–(5s4d)3D2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p)3P2 dark state are repumped back into the (5s2)1S0 ground state. Spectroscopy of 84Sr, 86Sr, 87Sr and 88Sr improves the value of the (5s5p)3P2–(5s4d)3D2 transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.

Ultra-long-range Rydberg molecules in a divalent atomic system

We report the creation of ultralong-range Sr

Testing universality of Efimov physics across broad and narrow Feshbach resonances

_2

Rydberg-blockade effects in Autler-Townes spectra of ultracold strontium

molecules comprising one ground-state

Rabi oscillations between atomic and molecular condensates driven with coherent one-color photoassociation.

5s^2

Numerical modeling of collisional dynamics of Sr in an optical dipole trap

^1S_0

Bose-Einstein condensation of Sr 88 through sympathetic cooling with Sr 87

atom and one atom in a