Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1912.01264

High partial-wave Feshbach resonances in an ultracold $^6$Li-$^{133}$Cs mixture

Bing Zhu, Häfner, Stephan, Binh Tran, Manuel Gerken, Juris Ulmanis, E. Tiemann, Matthias Weidemüller

Published Dec 3, 2019• 2 citations
arXivHTMLPDF

Abstract

We measure higher partial wave Feshbach resonances in an ultracold mixture of fermionic $^6$Li and bosonic $^{133}$Cs by magnetic field dependent atom-loss spectroscopy. For the $p$-wave Feshbach resonances we observe triplet structures corresponding to different projections of the pair rotation angular momentum onto the external magnetic field axis. We attribute the splittings to the spin-spin and spin-rotation couplings by modelling the observation using a full coupled-channel calculation. Comparison with an oversimplified model, estimating the spin-rotation coupling by describing the weakly bound close-channel molecular state with the perturbative multipole expansion, reveals the significant contribution of the molecular wavefunction at short internuclear distances. Our findings highlight the potential of Feshbach resonances in providing precise information on short- and intermediate-range molecular couplings and wavefunctions. The observed $d$-wave Feshbach resonances allow us to refine the LiCs singlet and triplet ground-state molecular potential curves at large internuclear separations.

DOI
10.48550/arxiv.1912.01264

Related papers

Spin-rotation coupling in p-wave Feshbach resonances

Bing Zhu, Häfner, Stephan, Binh Tran +4 more

We report evidence for spin-rotation coupling in $p$-wave Feshbach resonances in an ultracold mixture of fermionic $^6$Li and bosonic $^{133}$Cs lifting the commonly observed degeneracy of states with equal absolute value of orbital-angular-momentum projection on the external magnetic field. By employing magnetic field dependent atom-loss spectroscopy we find triplet structures in $p$-wave resonances. Comparison with coupled-channel calculations, including contributions from both spin-spin and spin-rotation interactions, yields a spin-rotation coupling parameter $|γ|=0.566(50)\times10^{-3}$. Our findings highlight the potential of Feshbach resonances in revealing subtle molecular couplings and providing precise information on electronic and nuclear wavefunctions, especially at short internuclear distance. The existence of a non-negligible spin-rotation splitting may have consequences for future classifications of $p$-wave superfluid phases in spin-polarized fermions.

arXiv:1910.12011•Oct 26, 2019•2 citations

Observation of interspecies 6 Li- 133 Cs Feshbach resonances

M. Repp, R. Pires, Juris Ulmanis +4 more

We report on the observation of 19 interspecies Feshbach resonances in an optically trapped ultracold Bose-Fermi mixture of ${}^{133}\text{Cs}$ and ${}^{6}\text{Li}$ in the two energetically lowest spin states. We assign the resonances to $s$- and $p$-wave molecular channels by a coupled-channels calculation, resulting in an accurate determination of LiCs ground-state potentials. Fits of the resonance position based on the undressed asymptotic bound state model do not provide the same level of accuracy as the coupled-channels calculation. Several broad $s$-wave resonances provide prospects to create fermionic LiCs molecules with a large dipole moment via Feshbach association followed by stimulated Raman passage. Two of the $s$-wave resonances overlap with a zero crossing of the Cs scattering length, which offers prospects for the investigation of polarons in an ultracold Li-Cs mixture.

arXiv:1211.2139•Physical Review A•Jan 3, 2013•99 citations

Precision Measurement of Spin-Dependent Dipolar Splitting in Li 6 p -Wave Feshbach Resonances

Shuai Peng, Sijia Peng, Lijun Ren +4 more

The magnetic dipolar splitting of a p-wave Feshbach resonance is governed by the spin-orbital configuration of the valence electrons in the triplet molecular state. We perform high-resolution trap-loss spectroscopy on ultracold ^{6}Li atoms to resolve this splitting with sub-milligauss precision. By comparing electron-spin-polarized (|m_{S}|=1) and electron-spin-mixture (m_{S}=0) configurations of the triplet state, we observe a clear spin-dependent reversal in the splitting structure, confirmed via momentum-resolved absorption imaging. This behavior directly reflects the interplay between electron spin projection m_{S} and orbital angular momentum m_{ℓ} in the molecular states. Our results provide a stringent benchmark for dipole-dipole interaction models and lay the groundwork for controlling the pairing in p-wave superfluid systems.

arXiv:2505.22409•Physical Review Letters•Sep 4, 2025•3 citations

Improved characterization of Feshbach resonances and interaction potentials between Na23 and Rb87 atoms

Zhichao Guo, Fan Jia, Bing Zhu +3 more

The ultracold mixture of $^{23}\mathrm{Na}$ and $^{87}\mathrm{Rb}$ atoms has become an important system for investigating physics in Bose-Bose atomic mixtures and for forming ultracold ground-state polar molecules. In this work, we provide an improved characterization of the most commonly used Feshbach resonance near 347.64 G between $^{23}\mathrm{Na}$ and $^{87}\mathrm{Rb}$ in their absolute ground states. We form Feshbach molecules using this resonance and measure their binding energies by dissociating them via magnetic-field modulation. We use the binding energies to refine the singlet and triplet potential-energy curves, using coupled-channel bound-state calculations. We then use coupled-channel scattering calculations on the resulting potentials to produce a high-precision mapping between magnetic field and scattering length. We also observe ten additional $s$-wave Feshbach resonances for $^{23}\mathrm{Na}$ and $^{87}\mathrm{Rb}$ in different combinations of Zeeman sublevels of the $F=1$ hyperfine states. Some of the resonances show two-body inelastic decay due to spin exchange. We compare the resonance properties with coupled-channel scattering calculations that full take account of inelastic properties.

arXiv:2108.01856•Physical Review A•Feb 11, 2022•17 citations

Feshbach Resonances in p -Wave Three-Body Recombination within Fermi-Fermi Mixtures of Open-Shell Li6 and Closed-Shell Yb173 Atoms

Alaina Green, Hui Li, Jun Hui See Toh +6 more

We report on the observation of magnetic Feshbach resonances in a Fermi-Fermi mixture of ultracold atoms with extreme mass imbalance and on their unique p-wave dominated three-body recombination processes.Our system consists of open-shell alkali-metal 6 Li and closed-shell 173 Yb atoms, both spin polarized and held at various temperatures between 1 and 20 μK.We confirm that Feshbach resonances in this system are solely the result of a weak separation-dependent hyperfine coupling between the electronic spin of 6 Li and the nuclear spin of 173 Yb.Our analysis also shows that three-body recombination rates are controlled by the identical fermion nature of the mixture, even in the presence of s-wave collisions between the two species and with recombination rate coefficients outside the Wigner threshold regime at our lowest temperature.Specifically, a comparison of experimental and theoretical line shapes of the recombination process indicates that the characteristic asymmetric line shape as a function of applied magnetic field and a maximum recombination rate coefficient that is independent of temperature can only be explained by triatomic collisions with nonzero, p-wave total orbital angular momentum.The resonances can be used to form ultracold doublet ground-state molecules and to simulate quantum superfluidity in mass-imbalanced mixtures.

arXiv:1912.04874•Physical Review X•Aug 14, 2020•55 citations

From two-body to many-body physics in an ultracold Bose-Fermi mixture of Li and Cs atoms

Häfner, Stephan Andreas

This thesis reports on scattering experiments performed with an ultracold mixture of fermionic 6Li and bosonic 133Cs atoms, studying two-, few-, and many-body effects in a highly mass-imbalanced system. To this end, the existing apparatus for the creation of ultracold gases is extended and improved by gray molasses cooling of 6Li and high-resolution absorption imaging. s-, p-, and d-wave Feshbach resonances in the two energetically lowest hyperfine channels are detected via atom-loss and binding energy spectroscopy. These measurements in combination with the coupled channels modeling provide a ten-fold improved parametrization of the interspecies s-wave scattering length and precise determination of the LiCs molecular potential curves. For the first time effects of spin-rotation coupling in Feshbach resonances are observed, reflected in a triplet splitting of the p-wave components. The influence of the intraspecies scattering length on the heteronuclear Efimov scenario is studied by means of threebody loss rate measurements in the vicinity of two Feshbach resonances, characterized either by a positive or negative intraspecies scattering length. The measurements are quantitatively compared to the hyperspherical adiabatic formalism. The positive intraspecies scattering length can be interpreted as three-body parameter. The impact of few-body physics in the many-body impurity problem is discussed and prospects for realization of quantum degenerate Bose-Fermi mixtures with large mass imbalance are provided.

•Jan 1, 2018•1 citation
High partial-wave Feshbach resonances in an ultracold 6^66Li-133^{133}133Cs mixture
We measure higher partial wave Feshbach resonances in an ultracold mixture of fermionic 6^66Li and bosonic 133^{133}133Cs by magnetic field dependent atom-loss spectroscopy. For the ppp-wave Feshbach resonances we observe triplet structures corresponding to different projections of the pair rotation angular momentum onto the external magnetic field axis. We attribute the splittings to the spin-spin and spin-rotation couplings by modelling the observation using a full coupled-channel calculation. Comparison with an oversimplified model, estimating the spin-rotation coupling by describing the weakly bound close-channel molecular state with the perturbative multipole expansion, reveals the significant contribution of the molecular wavefunction at short internuclear distances. Our findings highlight the potential of Feshbach resonances in providing precise information on short- and intermediate-range molecular couplings and wavefunctions. The observed ddd-wave Feshbach resonances allow us to refine the LiCs singlet and triplet ground-state molecular potential curves at large internuclear separations.
We report evidence for spin-rotation coupling in ppp-wave Feshbach resonances in an ultracold mixture of fermionic 6^66Li and bosonic 133^{133}133Cs lifting the commonly observed degeneracy of states with equal absolute value of orbital-angular-momentum projection on the external magnetic field. By employing magnetic field dependent atom-loss spectroscopy we find triplet structures in ppp-wave resonances. Comparison with coupled-channel calculations, including contributions from both spin-spin and spin-rotation interactions, yields a spin-rotation coupling parameter ∣γ∣=0.566(50)×10−3|γ|=0.566(50)\times10^{-3}∣γ∣=0.566(50)×10−3. Our findings highlight the potential of Feshbach resonances in revealing subtle molecular couplings and providing precise information on electronic and nuclear wavefunctions, especially at short internuclear distance. The existence of a non-negligible spin-rotation splitting may have consequences for future classifications of ppp-wave superfluid phases in spin-polarized fermions.
We report on the observation of 19 interspecies Feshbach resonances in an optically trapped ultracold Bose-Fermi mixture of 133Cs{}^{133}\text{Cs}133Cs and 6Li{}^{6}\text{Li}6Li in the two energetically lowest spin states. We assign the resonances to sss- and ppp-wave molecular channels by a coupled-channels calculation, resulting in an accurate determination of LiCs ground-state potentials. Fits of the resonance position based on the undressed asymptotic bound state model do not provide the same level of accuracy as the coupled-channels calculation. Several broad sss-wave resonances provide prospects to create fermionic LiCs molecules with a large dipole moment via Feshbach association followed by stimulated Raman passage. Two of the sss-wave resonances overlap with a zero crossing of the Cs scattering length, which offers prospects for the investigation of polarons in an ultracold Li-Cs mixture.
The magnetic dipolar splitting of a p-wave Feshbach resonance is governed by the spin-orbital configuration of the valence electrons in the triplet molecular state. We perform high-resolution trap-loss spectroscopy on ultracold ^{6}Li atoms to resolve this splitting with sub-milligauss precision. By comparing electron-spin-polarized (|m_{S}|=1) and electron-spin-mixture (m_{S}=0) configurations of the triplet state, we observe a clear spin-dependent reversal in the splitting structure, confirmed via momentum-resolved absorption imaging. This behavior directly reflects the interplay between electron spin projection m_{S} and orbital angular momentum m_{ℓ} in the molecular states. Our results provide a stringent benchmark for dipole-dipole interaction models and lay the groundwork for controlling the pairing in p-wave superfluid systems.
The ultracold mixture of 23Na^{23}\mathrm{Na}23Na and 87Rb^{87}\mathrm{Rb}87Rb atoms has become an important system for investigating physics in Bose-Bose atomic mixtures and for forming ultracold ground-state polar molecules. In this work, we provide an improved characterization of the most commonly used Feshbach resonance near 347.64 G between 23Na^{23}\mathrm{Na}23Na and 87Rb^{87}\mathrm{Rb}87Rb in their absolute ground states. We form Feshbach molecules using this resonance and measure their binding energies by dissociating them via magnetic-field modulation. We use the binding energies to refine the singlet and triplet potential-energy curves, using coupled-channel bound-state calculations. We then use coupled-channel scattering calculations on the resulting potentials to produce a high-precision mapping between magnetic field and scattering length. We also observe ten additional sss-wave Feshbach resonances for 23Na^{23}\mathrm{Na}23Na and 87Rb^{87}\mathrm{Rb}87Rb in different combinations of Zeeman sublevels of the F=1F=1F=1 hyperfine states. Some of the resonances show two-body inelastic decay due to spin exchange. We compare the resonance properties with coupled-channel scattering calculations that full take account of inelastic properties.
We report on the observation of magnetic Feshbach resonances in a Fermi-Fermi mixture of ultracold atoms with extreme mass imbalance and on their unique p-wave dominated three-body recombination processes.Our system consists of open-shell alkali-metal 6 Li and closed-shell 173 Yb atoms, both spin polarized and held at various temperatures between 1 and 20 μK.We confirm that Feshbach resonances in this system are solely the result of a weak separation-dependent hyperfine coupling between the electronic spin of 6 Li and the nuclear spin of 173 Yb.Our analysis also shows that three-body recombination rates are controlled by the identical fermion nature of the mixture, even in the presence of s-wave collisions between the two species and with recombination rate coefficients outside the Wigner threshold regime at our lowest temperature.Specifically, a comparison of experimental and theoretical line shapes of the recombination process indicates that the characteristic asymmetric line shape as a function of applied magnetic field and a maximum recombination rate coefficient that is independent of temperature can only be explained by triatomic collisions with nonzero, p-wave total orbital angular momentum.The resonances can be used to form ultracold doublet ground-state molecules and to simulate quantum superfluidity in mass-imbalanced mixtures.
This thesis reports on scattering experiments performed with an ultracold mixture of fermionic 6Li and bosonic 133Cs atoms, studying two-, few-, and many-body effects in a highly mass-imbalanced system. To this end, the existing apparatus for the creation of ultracold gases is extended and improved by gray molasses cooling of 6Li and high-resolution absorption imaging. s-, p-, and d-wave Feshbach resonances in the two energetically lowest hyperfine channels are detected via atom-loss and binding energy spectroscopy. These measurements in combination with the coupled channels modeling provide a ten-fold improved parametrization of the interspecies s-wave scattering length and precise determination of the LiCs molecular potential curves. For the first time effects of spin-rotation coupling in Feshbach resonances are observed, reflected in a triplet splitting of the p-wave components. The influence of the intraspecies scattering length on the heteronuclear Efimov scenario is studied by means of threebody loss rate measurements in the vicinity of two Feshbach resonances, characterized either by a positive or negative intraspecies scattering length. The measurements are quantitatively compared to the hyperspherical adiabatic formalism. The positive intraspecies scattering length can be interpreted as three-body parameter. The impact of few-body physics in the many-body impurity problem is discussed and prospects for realization of quantum degenerate Bose-Fermi mixtures with large mass imbalance are provided.