Repeated output coupling of ultracold Feshbach molecules from a Cs BEC

Paper Part of Focus on New Frontiers of Cold Molecules Research We investigate magnetoassociation of ultracold Feshbach molecules from a Bose-Einstein condensate of Cs atoms and explore the spectrum of weakly bound molecular states close to the atomic threshold. By exploiting the variation of magnetic field experienced by a molecular cloud falling in the presence of a magnetic field gradient, we demonstrate the repeated output coupling of molecules from a single atomic cloud using a Feshbach resonance at 19.89 G. Using this method we are able to produce up to 24 separate pulses of molecules from a single atomic condensate, with a molecular pulse created every 7.2 ms. Furthermore, by careful control of the magnetic bias field and gradient we are able to utilise an avoided crossing in the bound state spectrum at 13.3 G to demonstrate exquisite control over the dynamics of the molecular clouds

A simple, versatile laser system for the creation of ultracold ground state molecules

Paper Part of Focus on New Frontiers of Cold Molecules Research A narrow-linewidth, dual-wavelength laser system is vital for the creation of ultracold ground state molecules via stimulated Raman adiabatic passage (STIRAP) from a weakly bound Feshbach state. Here we describe how a relatively simple apparatus consisting of a single fixed-length optical cavity can be used to narrow the linewidth of the two different wavelength lasers required for STIRAP simultaneously. The frequency of each of these lasers is referenced to the cavity and is continuously tunable away from the cavity modes through the use of non-resonant electro-optic modulators. Self-heterodyne measurements suggest the laser linewidths are reduced to several 100 Hz. In the context of 87Rb133Cs molecules produced via magnetoassociation on a Feshbach resonance, we demonstrate the performance of the laser system through one- and two-photon molecular spectroscopy. Finally, we demonstrate transfer of the molecules to the rovibrational ground state using STIRAP

Production of optically trapped 87RbCs Feshbach molecules

We report the production of Feshbach molecules in a crossed-beam dipole trap. A mixture of and is cooled close to quantum degeneracy before an interspecies Feshbach resonance at 197 G is used to associate up to molecules with a temperature of nK. The molecules are confined in the dipole trap with a lifetime of 0.21(1) s, long enough for future experiments exploring optical transfer to the absolute ground state. We have measured the magnetic moment of the Feshbach molecules in a magnetic bias field range between 181 and 185 G to demonstrate the ability to control the character of the molecular state. In addition, we have performed Feshbach spectroscopy in a field range from 0 to 1200 G and located three previously unobserved resonances at high magnetic fields

Feshbach resonances in ultracold 85Rb

We present 17 experimentally confirmed Feshbach resonances in optically trapped 85Rb. Seven of the resonances are in the ground-state channel (f,mf)=(2,+2)+(2,+2) and nine are in the excited-state channel (2,−2)+(2,−2). We find a wide resonance at high field in each of the two channels, offering possibilities for the formation of larger 85Rb condensates and studies of few-body physics. A detailed coupled-channel analysis is presented to characterize the resonances and also provides an understanding of the inelastic losses observed in the excited-state channel. In addition we have confirmed the existence of one narrow resonance in a (2,+2)+(3,+3) spin mixture

Creation of Ultracold 87Rb133Cs Molecules in the Rovibrational Ground State

We report the creation of a sample of over 1000 ultracold Rb 87 Cs 133 molecules in the lowest rovibrational ground state, from an atomic mixture of Rb 87 and Cs 133 , by magnetoassociation on an interspecies Feshbach resonance followed by stimulated Raman adiabatic passage (STIRAP). We measure the binding energy of the RbCs molecule to be hc×3811.576(1)  cm −1 and the |v '' =0,J '' =0⟩ to |v '' =0,J '' =2⟩ splitting to be h×2940.09(6)  MHz . Stark spectroscopy of the rovibrational ground state yields an electric dipole moment of 1.225(3)(8) D, where the values in parentheses are the statistical and systematic uncertainties, respectively. We can access a space-fixed dipole moment of 0.355(2)(4) D, which is substantially higher than in previous work