This thesis reports the observation of interspecies Feshbach resonances in an ultracold mixture of Rb and Cs atoms. A versatile combined magnetic and optical potential has been designed and constructed which is capable of bringing both $^{87}\rm{Rb}$ and $^{133}\rm{Cs}$ to degeneracy, and reaching high phase-space density in $^{85}\rm{Rb}$ . High phase-space density mixtures are the first step required in the production of ultracold polar molecules, the topic of much current research. The apparatus capitalises on the efficient capture of atoms by a magnetic trap from a magneto-optical trap, and the efficient sympathetic cooling of Cs by Rb therein. Upon transfer to the crossed optical dipole trap condensates in excess of $1\times10^{6}$ $^{87}\rm{Rb}$ atoms and approximately $1\times10^{5}$ $^{133}\rm{Cs}$ atoms are produced after direct evaporation and gravito-magnetic tilting of the potential. The observation of six interspecies $^{87}\rm{Rb}$ - $^{133}\rm{Cs}$ Feshbach resonances are reported, three of which had only been predicted theoretically, allowing testing and development of the theoretical model. Furthermore, the extrapolation of this model has predicted numerous Feshbach resonances between $^{85}\rm{Rb}$ and $^{133}\rm{Cs}$ , none of which have been experimentally observed prior to this work. The versatile nature of this apparatus is discussed, including the application of the current system to cooling of $^{85}\rm{Rb}$ . Initial experiments observed seven interspecies resonances, including a broad s-wave resonance at a magnetic field of $(644\pm2)$ G which is in excellent agreement with the theoretical prediction. Further work has revealed that fourteen Feshbach resonances exist in the 0-700 G magnetic field range between $^{85}\rm{Rb}$ and $^{133}\rm{Cs}$ atoms in the $\left|2,+2\right\rangle$ and $\left|3,+3\right\rangle$ states, respectively. Several of these resonances would be ideal for magneto-association of RbCs molecules, prior to transfer to the rovibrational ground-state.This thesis reports the observation of interspecies Feshbach resonances in an ultracold mixture of Rb and Cs atoms. A versatile combined magnetic and optical potential has been designed and constructed which is capable of bringing both $^{87}\rm{Rb}$ and $^{133}\rm{Cs}$ to degeneracy, and reaching high phase-space density in $^{85}\rm{Rb}$. High phase-space density mixtures are the first step required in the production of ultracold polar molecules, the topic of much current research. The apparatus capitalises on the efficient capture of atoms by a magnetic trap from a magneto-optical trap, and the efficient sympathetic cooling of Cs by Rb therein. Upon transfer to the crossed optical dipole trap condensates in excess of $1\times10^{6}$ $^{87}\rm{Rb}$ atoms and approximately $1\times10^{5}$ $^{133}\rm{Cs}$ atoms are produced after direct evaporation and gravito-magnetic tilting of the potential. The observation of six interspecies $^{87}\rm{Rb}$-$^{133}\rm{Cs}$ Feshbach resonances are reported, three of which had only been predicted theoretically, allowing testing and development of the theoretical model. Furthermore, the extrapolation of this model has predicted numerous Feshbach resonances between $^{85}\rm{Rb}$ and $^{133}\rm{Cs}$, none of which have been experimentally observed prior to this work. The versatile nature of this apparatus is discussed, including the application of the current system to cooling of $^{85}\rm{Rb}$. Initial experiments observed seven interspecies resonances, including a broad s-wave resonance at a magnetic field of $(644\pm2)$ G which is in excellent agreement with the theoretical prediction. Further work has revealed that fourteen Feshbach resonances exist in the 0-700 G magnetic field range between $^{85}\rm{Rb}$ and $^{133}\rm{Cs}$ atoms in the $\left|2,+2\right\rangle$ and $\left|3,+3\right\rangle$ states, respectively. Several of these resonances would be ideal for magneto-association of RbCs molecules, prior to transfer to the rovibrational ground-state.

Jan 1, 20120 citations

All-optical production of L7i Bose-Einstein condensation using Feshbach resonances

Noam Gross, Lev Khaykovich

We show an all-optical method of making $^{7}\text{L}\text{i}$ condensates using the tunability of the scattering length in the proximity of a Feshbach resonance. We report the observation of two Feshbach resonances on the $|F=1,{m}_{F}=0⟩$ state. A narrow (broad) resonance of 7 G (34 G) width is detected at $831\ifmmode\pm\else\textpm\fi{}4\text{ }\text{G}$ $({884}_{\ensuremath{-}13}^{+4}\text{ }\text{G})$. The position of the scattering length zero crossing between the resonances is found at $836\ifmmode\pm\else\textpm\fi{}4\text{ }\text{G}$. The broad resonance is shown to be favorable for runaway evaporation which we perform in a crossed-beam optical-dipole trap. Starting directly from the phase-space density of a magneto-optical trap we observe a Bose-Einstein condensation threshold in less than 3 s of forced evaporation.We show an all-optical method of making $^{7}\text{L}\text{i}$ condensates using the tunability of the scattering length in the proximity of a Feshbach resonance. We report the observation of two Feshbach resonances on the $|F=1,{m}_{F}=0⟩$ state. A narrow (broad) resonance of 7 G (34 G) width is detected at $831\ifmmode\pm\else\textpm\fi{}4\text{ }\text{G}$ $({884}_{\ensuremath{-}13}^{+4}\text{ }\text{G})$. The position of the scattering length zero crossing between the resonances is found at $836\ifmmode\pm\else\textpm\fi{}4\text{ }\text{G}$. The broad resonance is shown to be favorable for runaway evaporation which we perform in a crossed-beam optical-dipole trap. Starting directly from the phase-space density of a magneto-optical trap we observe a Bose-Einstein condensation threshold in less than 3 s of forced evaporation.

arXiv:0712.0717Physical Review AFeb 4, 200828 citations

Local Field Effects in Nonlinear and Quantum Optics

Charles M. Bowden, Aaron S. Manka, Jonathan P. Dowling +1 more

Springer eBooksJan 1, 19960 citations

Dysprosium dipolar Bose-Einstein condensate with broad Feshbach resonances

E. Lucioni, Luca Tanzi, Alessandro Fregosi +6 more

We produce Bose-Einstein condensates of $^{162}\mathrm{Dy}$ atoms employing an innovative technique based on a resonator-enhanced optical trap that allows efficient loading from the magneto-optical trap. We characterize the scattering properties of the ultracold atoms for magnetic fields between 6 and 30 G. In addition to the typical chaotic distribution of narrow Feshbach resonances in lanthanides, we discover two rather isolated broad features at around 22 G and 27 G. A characterization using the complementary measurements of losses, thermalization, anisotropic expansion, and molecular binding energy points towards resonances of predominant $s$ -wave character. Such resonances will ease the investigation of quantum phenomena relying on the interplay between dipole and contact interactions.We produce Bose-Einstein condensates of $^{162}\mathrm{Dy}$ atoms employing an innovative technique based on a resonator-enhanced optical trap that allows efficient loading from the magneto-optical trap. We characterize the scattering properties of the ultracold atoms for magnetic fields between 6 and 30 G. In addition to the typical chaotic distribution of narrow Feshbach resonances in lanthanides, we discover two rather isolated broad features at around 22 G and 27 G. A characterization using the complementary measurements of losses, thermalization, anisotropic expansion, and molecular binding energy points towards resonances of predominant $s$-wave character. Such resonances will ease the investigation of quantum phenomena relying on the interplay between dipole and contact interactions.

arXiv:1803.10676Physical Review AJun 29, 201838 citations

^{87}\rm{Rb}

and

^{133}\rm{Cs}

to degeneracy, and reaching high phase-space density in

^{85}\rm{Rb}

. High phase-space density mixtures are the first step required in the production of ultracold polar molecules, the topic of much current research. The apparatus capitalises on the efficient capture of atoms by a magnetic trap from a magneto-optical trap, and the efficient sympathetic cooling of Cs by Rb therein. Upon transfer to the crossed optical dipole trap condensates in excess of

1\times10^{6}

^{87}\rm{Rb}

atoms and approximately

1\times10^{5}

^{133}\rm{Cs}

atoms are produced after direct evaporation and gravito-magnetic tilting of the potential. The observation of six interspecies

^{87}\rm{Rb}

^{133}\rm{Cs}

Feshbach resonances are reported, three of which had only been predicted theoretically, allowing testing and development of the theoretical model. Furthermore, the extrapolation of this model has predicted numerous Feshbach resonances between

^{85}\rm{Rb}

and

^{133}\rm{Cs}

, none of which have been experimentally observed prior to this work. The versatile nature of this apparatus is discussed, including the application of the current system to cooling of

^{85}\rm{Rb}

. Initial experiments observed seven interspecies resonances, including a broad s-wave resonance at a magnetic field of

(644\pm2)

G which is in excellent agreement with the theoretical prediction. Further work has revealed that fourteen Feshbach resonances exist in the 0-700 G magnetic field range between

^{85}\rm{Rb}

and

^{133}\rm{Cs}

atoms in the

\left|2,+2\right\rangle

and

\left|3,+3\right\rangle

states, respectively. Several of these resonances would be ideal for magneto-association of RbCs molecules, prior to transfer to the rovibrational ground-state.

We show an all-optical method of making

^{7}\text{L}\text{i}

condensates using the tunability of the scattering length in the proximity of a Feshbach resonance. We report the observation of two Feshbach resonances on the

|F=1,{m}_{F}=0⟩

state. A narrow (broad) resonance of 7 G (34 G) width is detected at $831\ifmmode\pm\else\textpm\fi{}4\text{ }\text{G}$ $({884}_{\ensuremath{-}13}^{+4}\text{ }\text{G})$. The position of the scattering length zero crossing between the resonances is found at $836\ifmmode\pm\else\textpm\fi{}4\text{ }\text{G}$. The broad resonance is shown to be favorable for runaway evaporation which we perform in a crossed-beam optical-dipole trap. Starting directly from the phase-space density of a magneto-optical trap we observe a Bose-Einstein condensation threshold in less than 3 s of forced evaporation.

We produce Bose-Einstein condensates of

^{162}\mathrm{Dy}

atoms employing an innovative technique based on a resonator-enhanced optical trap that allows efficient loading from the magneto-optical trap. We characterize the scattering properties of the ultracold atoms for magnetic fields between 6 and 30 G. In addition to the typical chaotic distribution of narrow Feshbach resonances in lanthanides, we discover two rather isolated broad features at around 22 G and 27 G. A characterization using the complementary measurements of losses, thermalization, anisotropic expansion, and molecular binding energy points towards resonances of predominant

s

-wave character. Such resonances will ease the investigation of quantum phenomena relying on the interplay between dipole and contact interactions.