Magnetically tunable Feshbach resonances exist in ultracold collisions between atoms in $^{2}\mathrm{S}$ and ${}^{3}{\mathrm{P}}_{0}$ states, such as an alkali-metal atom colliding with Yb or Sr in a clock state. We investigate the mechanisms of these resonances and identify the terms in the collision Hamiltonian responsible for them. They involve indirect coupling between the open and closed channels, via intermediate channels involving atoms in ${}^{3}{\mathrm{P}}_{1}$ states. The resonance widths are generally proportional to the square of the magnetic field and are strongly enhanced when the magnitude of the background scattering length is large. For any given pair of atoms, the scattering length can be tuned discretely by choosing different isotopes of the ${}^{3}{\mathrm{P}}_{0}$ atom. For each combination of an alkali-metal atom and either Yb or Sr, we consider the prospects of finding an isotopic combination that has both a large background scattering length and resonances at a high but experimentally accessible field. We conclude that $^{87}\mathrm{Rb}+\mathrm{Yb}$ , $\mathrm{Cs}+\mathrm{Yb}$ , and $^{85}\mathrm{Rb}+\mathrm{Sr}$ are particularly promising combinations.Magnetically tunable Feshbach resonances exist in ultracold collisions between atoms in $^{2}\mathrm{S}$ and ${}^{3}{\mathrm{P}}_{0}$ states, such as an alkali-metal atom colliding with Yb or Sr in a clock state. We investigate the mechanisms of these resonances and identify the terms in the collision Hamiltonian responsible for them. They involve indirect coupling between the open and closed channels, via intermediate channels involving atoms in ${}^{3}{\mathrm{P}}_{1}$ states. The resonance widths are generally proportional to the square of the magnetic field and are strongly enhanced when the magnitude of the background scattering length is large. For any given pair of atoms, the scattering length can be tuned discretely by choosing different isotopes of the ${}^{3}{\mathrm{P}}_{0}$ atom. For each combination of an alkali-metal atom and either Yb or Sr, we consider the prospects of finding an isotopic combination that has both a large background scattering length and resonances at a high but experimentally accessible field. We conclude that $^{87}\mathrm{Rb}+\mathrm{Yb}$, $\mathrm{Cs}+\mathrm{Yb}$, and $^{85}\mathrm{Rb}+\mathrm{Sr}$ are particularly promising combinations.

arXiv:2211.07557Physical Review ResearchFeb 13, 20232 citations

Scattering models for ultracold atoms

Eric Braaten, Masaoki Kusunoki, Dongqing Zhang

arXiv:0709.0499Annals of PhysicsFeb 20, 200877 citations

Isotope dependent interactions in a mixture of ultracold atoms

F. Baumer

Within the scope of this thesis, comprehensive experimental studies on interspecies interactions between 87Rb and various isotopes of Yb at temperatures in the µK regime have been performed. The interactions between Yb and 87Rb manifested themselves through interspecies thermalization and - in the case of 174Yb and 87Rb - through phase separation. The experimental investigations described in this thesis were carried out within a research project, whose long term goal is the creation of ultracold YbRb molecules. The experimental apparatus is designed for combined cooling and trapping of gaseous Yb and Rb atomic samples to the µK and nK regime. Due to the particular magnetic properties of Rb and Yb, a unique combination of trapping potentials, which allows for independent manipulation of ultracold 87Rb and Yb atoms, was used for the described measurements. The combined trap setup consisted of a Ioffe-Pritchard-type magnetic trap (MT) for 87Rb and a bichromatic optical dipole trap (BIODT) for Yb. The main scientific result of this PhD work is the observation of phase separation in a thermal mixture of 174Yb and 87Rb in the µK regime and the detailed experimental study and theoretical analysis of this unexpected effect. Analysis of the experimental observations required accurate modeling of the trapping potentials in order to extract quantitative results on the interspecies interaction. These results can be related to the 174Yb 87Rb interspecies s-wave scattering length, using an approach, which not only describes mean field effects but also includes multiple-particle interactions. This analysis yields a value for the s-wave scattering length of a_(87-174)=4710 (+3970) (-1520) a0, which is extraordinarily large. Indeed, this is to our knowledge the largest interspecies scattering length that has been observed to date at zero magnetic field. In contrast to observations of phase separation in other systems that have been made so far, phase separation between 174Yb and 87Rb as described in this PhD work is observed in purely thermal and not quantum degenerate samples. In this thesis, the study of phase separation in a 174Yb87Rb mixture was supplemented by an investigation of elastic collision rates for several of the Yb isotopes. The most notable finding was that for the combination \Yb{170}87Rb the interspecies scattering length has a value of a_(87-174)=6.6 (+3.5) (-2.9)a0 and is thus extremely small. The results of our studies on interspecies interactions between 87Rb and Yb can be used for model calculations on the YbRb molecular ground state potential: E. Tiesinga and S. Maxwell from the atomic theory group at NIST determined a Lennard-Jones potential, which quantitatively reproduces the present experimental observations. This knowledge will significantly help to provide a strategy for the controlled transfer of excited state YbRb* molecules to a selected ground state.Within the scope of this thesis, comprehensive experimental studies on interspecies interactions between 87Rb and various isotopes of Yb at temperatures in the µK regime have been performed. The interactions between Yb and 87Rb manifested themselves through interspecies thermalization and - in the case of 174Yb and 87Rb - through phase separation. The experimental investigations described in this thesis were carried out within a research project, whose long term goal is the creation of ultracold YbRb molecules. The experimental apparatus is designed for combined cooling and trapping of gaseous Yb and Rb atomic samples to the µK and nK regime. Due to the particular magnetic properties of Rb and Yb, a unique combination of trapping potentials, which allows for independent manipulation of ultracold 87Rb and Yb atoms, was used for the described measurements. The combined trap setup consisted of a Ioffe-Pritchard-type magnetic trap (MT) for 87Rb and a bichromatic optical dipole trap (BIODT) for Yb. The main scientific result of this PhD work is the observation of phase separation in a thermal mixture of 174Yb and 87Rb in the µK regime and the detailed experimental study and theoretical analysis of this unexpected effect. Analysis of the experimental observations required accurate modeling of the trapping potentials in order to extract quantitative results on the interspecies interaction. These results can be related to the 174Yb 87Rb interspecies s-wave scattering length, using an approach, which not only describes mean field effects but also includes multiple-particle interactions. This analysis yields a value for the s-wave scattering length of a_(87-174)=4710 (+3970) (-1520) a0, which is extraordinarily large. Indeed, this is to our knowledge the largest interspecies scattering length that has been observed to date at zero magnetic field. In contrast to observations of phase separation in other systems that have been made so far, phase separation between 174Yb and 87Rb as described in this PhD work is observed in purely thermal and not quantum degenerate samples. In this thesis, the study of phase separation in a 174Yb87Rb mixture was supplemented by an investigation of elastic collision rates for several of the Yb isotopes. The most notable finding was that for the combination \Yb{170}87Rb the interspecies scattering length has a value of a_(87-174)=6.6 (+3.5) (-2.9)a0 and is thus extremely small. The results of our studies on interspecies interactions between 87Rb and Yb can be used for model calculations on the YbRb molecular ground state potential: E. Tiesinga and S. Maxwell from the atomic theory group at NIST determined a Lennard-Jones potential, which quantitatively reproduces the present experimental observations. This knowledge will significantly help to provide a strategy for the controlled transfer of excited state YbRb* molecules to a selected ground state.

Jan 1, 20102 citations

Beyond s-wave scattering for ultracold atoms

Ross Williams, Lindsay J. LeBlanc, Karina K. Jimenez Garcia +4 more

ScienceJan 20, 20120 citations

Scattering lengths in isotopologues of the RbYb system

Mateusz Borkowski, Piotr Szymon Żuchowski, R. Ciuryło +7 more

We model the binding energies of rovibrational levels of the RbYb molecule using experimental data from two-color photoassociation spectroscopy in mixtures of ultracold ${}^{87}$ Rb with various Yb isotopes. The model uses a theoretical potential based on state-of-the-art ab initio potentials, further improved by least-squares fitting to the experimental data. We have fixed the number of bound states supported by the potential curve, so that the model is mass scaled, that is, it accurately describes the bound-state energies for all measured isotopic combinations. Such a model enables an accurate prediction of the $s$ -wave scattering lengths of all isotopic combinations of the RbYb system. The reduced mass range is broad enough to cover the full scattering lengths range from $\ensuremath{-}\ensuremath{\infty}$ to $+\ensuremath{\infty}$. For example, the ${}^{87}$ Rb ${}^{174}$ Yb system is characterized by a large positive scattering length of $+880(120)$ a.u., while ${}^{87}$ Rb ${}^{173}$ Yb has $a=\ensuremath{-}626(88)$ a.u. On the other hand ${}^{87}$ Rb ${}^{170}$ Yb has a very small scattering length of $\ensuremath{-}11.5(2.5)$ a.u. confirmed by the pair's extremely low thermalization rate. For isotopic combinations including ${}^{85}$ Rb the variation of the interspecies scattering lengths is much smoother ranging from $+39.0(1.6)$ a.u. for ${}^{85}$ Rb ${}^{176}$ Yb to $+230(12)$ a.u. in the case of ${}^{85}$ Rb ${}^{168}$ Yb. Hyperfine corrections to these scattering lengths are also given. We further complement the fitted potential with interaction parameters calculated from alternative methods. The recommended value of the van der Waals coefficient is ${C}_{6}=2837(13)$ a.u. agrees with but is more precise than the current state-of-the-art theoretical predictions [M. S. Safronova, S. G. Porsev, and C. W. Clark, Phys. Rev. Lett. 109, 230802 (2012)].We model the binding energies of rovibrational levels of the RbYb molecule using experimental data from two-color photoassociation spectroscopy in mixtures of ultracold ${}^{87}$Rb with various Yb isotopes. The model uses a theoretical potential based on state-of-the-art ab initio potentials, further improved by least-squares fitting to the experimental data. We have fixed the number of bound states supported by the potential curve, so that the model is mass scaled, that is, it accurately describes the bound-state energies for all measured isotopic combinations. Such a model enables an accurate prediction of the $s$-wave scattering lengths of all isotopic combinations of the RbYb system. The reduced mass range is broad enough to cover the full scattering lengths range from $\ensuremath{-}\ensuremath{\infty}$ to $+\ensuremath{\infty}$. For example, the ${}^{87}$Rb${}^{174}$Yb system is characterized by a large positive scattering length of $+880(120)$ a.u., while ${}^{87}$Rb${}^{173}$Yb has $a=\ensuremath{-}626(88)$ a.u. On the other hand ${}^{87}$Rb${}^{170}$Yb has a very small scattering length of $\ensuremath{-}11.5(2.5)$ a.u. confirmed by the pair's extremely low thermalization rate. For isotopic combinations including ${}^{85}$Rb the variation of the interspecies scattering lengths is much smoother ranging from $+39.0(1.6)$ a.u. for ${}^{85}$Rb${}^{176}$Yb to $+230(12)$ a.u. in the case of ${}^{85}$Rb${}^{168}$Yb. Hyperfine corrections to these scattering lengths are also given. We further complement the fitted potential with interaction parameters calculated from alternative methods. The recommended value of the van der Waals coefficient is ${C}_{6}=2837(13)$ a.u. agrees with but is more precise than the current state-of-the-art theoretical predictions [M. S. Safronova, S. G. Porsev, and C. W. Clark, Phys. Rev. Lett. 109, 230802 (2012)].

arXiv:1309.3131Physical Review ANov 20, 201364 citations

Scattering and resonance of ultracold atoms with spin-orbit coupling

Long Zhang, Youjin Deng, Peng Zhang

Nov 29, 20120 citations

Magnetically tunable Feshbach resonances exist in ultracold collisions between atoms in

^{2}\mathrm{S}

and

{}^{3}{\mathrm{P}}_{0}

states, such as an alkali-metal atom colliding with Yb or Sr in a clock state. We investigate the mechanisms of these resonances and identify the terms in the collision Hamiltonian responsible for them. They involve indirect coupling between the open and closed channels, via intermediate channels involving atoms in

{}^{3}{\mathrm{P}}_{1}

states. The resonance widths are generally proportional to the square of the magnetic field and are strongly enhanced when the magnitude of the background scattering length is large. For any given pair of atoms, the scattering length can be tuned discretely by choosing different isotopes of the

{}^{3}{\mathrm{P}}_{0}

atom. For each combination of an alkali-metal atom and either Yb or Sr, we consider the prospects of finding an isotopic combination that has both a large background scattering length and resonances at a high but experimentally accessible field. We conclude that

^{87}\mathrm{Rb}+\mathrm{Yb}

\mathrm{Cs}+\mathrm{Yb}

, and

^{85}\mathrm{Rb}+\mathrm{Sr}

are particularly promising combinations.

We model the binding energies of rovibrational levels of the RbYb molecule using experimental data from two-color photoassociation spectroscopy in mixtures of ultracold

{}^{87}

Rb with various Yb isotopes. The model uses a theoretical potential based on state-of-the-art ab initio potentials, further improved by least-squares fitting to the experimental data. We have fixed the number of bound states supported by the potential curve, so that the model is mass scaled, that is, it accurately describes the bound-state energies for all measured isotopic combinations. Such a model enables an accurate prediction of the

s

-wave scattering lengths of all isotopic combinations of the RbYb system. The reduced mass range is broad enough to cover the full scattering lengths range from $\ensuremath{-}\ensuremath{\infty}$ to $+\ensuremath{\infty}$. For example, the

{}^{87}

{}^{174}

Yb system is characterized by a large positive scattering length of

+880(120)

a.u., while

{}^{87}

{}^{173}

Yb has $a=\ensuremath{-}626(88)$ a.u. On the other hand

{}^{87}

{}^{170}

Yb has a very small scattering length of $\ensuremath{-}11.5(2.5)$ a.u. confirmed by the pair's extremely low thermalization rate. For isotopic combinations including

{}^{85}

Rb the variation of the interspecies scattering lengths is much smoother ranging from

+39.0(1.6)

a.u. for

{}^{85}

{}^{176}

Yb to

+230(12)

a.u. in the case of

{}^{85}

{}^{168}

Yb. Hyperfine corrections to these scattering lengths are also given. We further complement the fitted potential with interaction parameters calculated from alternative methods. The recommended value of the van der Waals coefficient is

{C}_{6}=2837(13)

a.u. agrees with but is more precise than the current state-of-the-art theoretical predictions [M. S. Safronova, S. G. Porsev, and C. W. Clark, Phys. Rev. Lett. 109, 230802 (2012)].