Margaret Harris

Optimization of sub-Doppler DAVLL on the rubidium D2 line
ML Harris, SL Cornish, A Tripathi and IG Hughes
J. Phys. B: At. Mol. Opt. Phys. 41, 085401 (2008)

We discuss the physics of sub-Doppler DAVLL spectroscopy, which employs a pump beam with an axial magnetic field to induce dichroism in an atomic vapour. The dichroism is measured by a counterpropagating probe beam, while the pump generates sub-Doppler spectral features. The magnitude of the field is chosen to shift the frequency of the absorption features by an amount comparable to their linewidth. The reference signals obtained are ideal for laser frequency discriminant signals (laser 'locking' to the atomic transition) without frequency modulation. We discuss the sensitivity of the spectra to magnetic field, laser power and polarization purity, and suggest operating parameters for the 87Rb F = 2 --> F' = 3, 2 crossover transition which maximize the signal amplitude and gradient.

Magnetic trapping of a cold Rb-Cs atomic mixture
ML Harris, P Tierney, SL Cornish
J. Phys. B: At. Mol. Opt. Phys. 41, 035303 (2008) [arXiv]

We present an apparatus for the study of an ultracold gaseous atomic mixture of 133Cs and 87Rb. The mixture is prepared using a double magneto-optical trap (MOT) system in which a two-species pyramid MOT acts as a source of cold atoms for a `science' MOT. Measurements of the interspecies trap loss rate coefficients beta_RbCs and beta_CsRb in the science MOT are reported. After the initial MOT phase, atoms in the mixture are optically pumped into the magnetically trappable |F=3,m_F=-3> and |F=1,m_F=-1> states of Cs and Rb (respectively) and loaded into an Ioffe-Pritchard magnetic trap. We demonstrate a novel technique for limiting the interspecies loss rate in the science MOT by spatially separating the two trapped atom clouds, which greatly enhances the number of atoms which can be loaded into the magnetic trap.

Polarization spectroscopy of rubidium and cesium
ML Harris, CS Adams, SL Cornish, IC McLeod, E Tarleton, IG Hughes
Phys Rev A 73, 062509 (2006) [arXiv]

We develop a theoretical treatment of polarization spectroscopy and use it to make predictions about the general form of polarization spectra in the alkali-metal atoms. Using our model, we generate theoretical spectra for the D2 transitions in 87Rb, 85Rb, and 133Cs. Experiments demonstrate that the model accurately reproduces spectra of transitions from the upper hyperfine level of the ground state only. Among these, the closed transition F->F'+1 dominates, with a steep gradient through line center ideally suited for use as a reference in laser locking.

Content © Margaret Harris, Durham University 2005