Abstract We investigate ultracold magnetic-field-assisted collisions in the so far unexplored ErYb system. The nonsphericity of the Er atom leads to weakly anisotropic interactions that provide the mechanism for Feshbach resonances to emerge. The resonances are moderately sparsely distributed with a density of 0.1–0.3 G−1 and exhibit chaotic statistics characterized by a Brody parameter η ≈ 0.5–0.7. The chaotic behaviour of Feshbach resonances is accompanied by strong mixing of magnetic and rotational quantum numbers in near-threshold bound states. We predict the existence of broad resonances at fields < 300 G that may be useful for the precise control of scattering properties and magnetoassociation of ErYb molecules. The high number of bosonic Er–Yb isotopic combinations gives many opportunities for mass scaling of interactions. Uniquely, two isotopic combinations have nearly identical reduced masses (differing by less than 10−5 relative) that we expect to have strikingly similar Feshbach resonance spectra, which would make it possible to experimentally measure their sensitivity to hypothetical variations of proton-to-electron mass ratio.Abstract We investigate ultracold magnetic-field-assisted collisions in the so far unexplored ErYb system. The nonsphericity of the Er atom leads to weakly anisotropic interactions that provide the mechanism for Feshbach resonances to emerge. The resonances are moderately sparsely distributed with a density of 0.1–0.3 G−1 and exhibit chaotic statistics characterized by a Brody parameter η ≈ 0.5–0.7. The chaotic behaviour of Feshbach resonances is accompanied by strong mixing of magnetic and rotational quantum numbers in near-threshold bound states. We predict the existence of broad resonances at fields < 300 G that may be useful for the precise control of scattering properties and magnetoassociation of ErYb molecules. The high number of bosonic Er–Yb isotopic combinations gives many opportunities for mass scaling of interactions. Uniquely, two isotopic combinations have nearly identical reduced masses (differing by less than 10−5 relative) that we expect to have strikingly similar Feshbach resonance spectra, which would make it possible to experimentally measure their sensitivity to hypothetical variations of proton-to-electron mass ratio.

arXiv:1910.03077New Journal of PhysicsJan 15, 202010 citations

Theory of Ultracold Feshbach Molecules

Thomas M. Hanna, Hugo E. L. Martay, Thorsten Köhler

Jun 25, 20091 citation

Theory of Ultracold Feshbach Molecules

Thorsten Köhler, Thomas M. Hanna, Hugo E. L. Martay

CRC Press eBooksJun 25, 20090 citations

Magnetically tunable Feshbach resonances in Li+Er

Maykel Leonardo González-Martínez, Piotr Szymon Żuchowski

We explore the magnetic Feshbach spectra of ultracold ground-state Li+Er systems. Our calculations predict many tunable resonances at fields below 1000 G that could be stably tuned in ultracold experiments. We show that Li+Er spectra are much less congested than those of systems involving heavier highly magnetic atoms and exhibit nonchaotic properties. These features would facilitate identifying and addressing individual resonances. We derive a simple model for the mass-scaling shifting of low-field resonances that may simplify designing experiments with different Er bosonic isotopes. Our work establishes Li+Er as very promising systems for quantum simulation, precision measurements and the formation of polar paramagnetic molecules.We explore the magnetic Feshbach spectra of ultracold ground-state Li+Er systems. Our calculations predict many tunable resonances at fields below 1000 G that could be stably tuned in ultracold experiments. We show that Li+Er spectra are much less congested than those of systems involving heavier highly magnetic atoms and exhibit nonchaotic properties. These features would facilitate identifying and addressing individual resonances. We derive a simple model for the mass-scaling shifting of low-field resonances that may simplify designing experiments with different Er bosonic isotopes. Our work establishes Li+Er as very promising systems for quantum simulation, precision measurements and the formation of polar paramagnetic molecules.

arXiv:1506.02496Physical Review AAug 24, 201525 citations

Enhanced Sensitivity to Fundamental Constants In Ultracold Atoms and Molecules near Feshbach Resonances

Cheng Chin, V. V. Flambaum

Bulletin of the American Physical SocietyJun 7, 20070 citations

Feshbach resonances of large-mass-imbalance Er-Li mixtures

F. Schäfer, N. Mizukami, Yoshiro Takahashi

We report on the experimental observation of Feshbach resonances in large-mass-imbalance mixtures of erbium (Er) and lithium (Li). All combinations of $^{168}\mathrm{Er}, ^{166}\mathrm{Er}$ , and $^{7}\mathrm{Li}, ^{6}\mathrm{Li}$ are cooled to temperatures of a few microkelvin, partially by means of sympathetic cooling together with ytterbium (Yb) as a third mixture component. The Er-Li inelastic interspecies collisional properties are studied for magnetic fields up to $680\phantom{\rule{0.28em}{0ex}}\mathrm{G}$ . In all cases, resonant interspecies loss features, indicative of Feshbach resonances, have been observed. While most resonances have sub-Gauss widths, a few of them are broad and feature widths of several Gauss. Those broad resonances are a key to the realization of ultracold Er-Li quantum gas mixtures with tunable interactions.We report on the experimental observation of Feshbach resonances in large-mass-imbalance mixtures of erbium (Er) and lithium (Li). All combinations of $^{168}\mathrm{Er}, ^{166}\mathrm{Er}$, and $^{7}\mathrm{Li}, ^{6}\mathrm{Li}$ are cooled to temperatures of a few microkelvin, partially by means of sympathetic cooling together with ytterbium (Yb) as a third mixture component. The Er-Li inelastic interspecies collisional properties are studied for magnetic fields up to $680\phantom{\rule{0.28em}{0ex}}\mathrm{G}$. In all cases, resonant interspecies loss features, indicative of Feshbach resonances, have been observed. While most resonances have sub-Gauss widths, a few of them are broad and feature widths of several Gauss. Those broad resonances are a key to the realization of ultracold Er-Li quantum gas mixtures with tunable interactions.

arXiv:2111.08130Physical Review AJan 24, 202222 citations

We report on the experimental observation of Feshbach resonances in large-mass-imbalance mixtures of erbium (Er) and lithium (Li). All combinations of

^{168}\mathrm{Er}, ^{166}\mathrm{Er}

, and

^{7}\mathrm{Li}, ^{6}\mathrm{Li}

are cooled to temperatures of a few microkelvin, partially by means of sympathetic cooling together with ytterbium (Yb) as a third mixture component. The Er-Li inelastic interspecies collisional properties are studied for magnetic fields up to

680\phantom{\rule{0.28em}{0ex}}\mathrm{G}

. In all cases, resonant interspecies loss features, indicative of Feshbach resonances, have been observed. While most resonances have sub-Gauss widths, a few of them are broad and feature widths of several Gauss. Those broad resonances are a key to the realization of ultracold Er-Li quantum gas mixtures with tunable interactions.