We report on the experimental observation of a strongly interacting gas of ultracold two-electron fermions with an orbital degree of freedom and magnetically tunable interactions. This realization has been enabled by the demonstration of a novel kind of Feshbach resonance occurring in the scattering of two (173)Yb atoms in different nuclear and electronic states. The strongly interacting regime at resonance is evidenced by the observation of anisotropic hydrodynamic expansion of the two-orbital Fermi gas. These results pave the way towards the realization of new quantum states of matter with strongly correlated fermions with an orbital degree of freedom.We report on the experimental observation of a strongly interacting gas of ultracold two-electron fermions with an orbital degree of freedom and magnetically tunable interactions. This realization has been enabled by the demonstration of a novel kind of Feshbach resonance occurring in the scattering of two (173)Yb atoms in different nuclear and electronic states. The strongly interacting regime at resonance is evidenced by the observation of anisotropic hydrodynamic expansion of the two-orbital Fermi gas. These results pave the way towards the realization of new quantum states of matter with strongly correlated fermions with an orbital degree of freedom.

arXiv:1509.04256Physical Review LettersDec 21, 2015145 citations

Strongly Interacting Fermi-Fermi Mixture of $^{161}$ Dy and $^{40}$ KStrongly Interacting Fermi-Fermi Mixture of $^{161}$Dy and $^{40}$K

Cornelis Ravensbergen, Elisa Soave, Vincent Le Corre +4 more

We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of $^{161}$ Dy and $^{40}$ K, we identify a broad Feshbach resonance centered at a magnetic field of 218 $\,$ G. In the strongly interacting regime, we demonstrate hydrodynamic behavior in the expansion after release from the trap. Lifetime studies on resonance show that the fermionic nature of the system suppresses inelastic few-body processes by several orders of magnitude. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of $^{161}$Dy and $^{40}$K, we identify a broad Feshbach resonance centered at a magnetic field of 218$\,$G. In the strongly interacting regime, we demonstrate hydrodynamic behavior in the expansion after release from the trap. Lifetime studies on resonance show that the fermionic nature of the system suppresses inelastic few-body processes by several orders of magnitude. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.

Sep 8, 20190 citations

Reaching a Fermi-superfluid state near an orbital Feshbach resonance

Junjun Xu, Ren Zhang, Yanting Cheng +3 more

We propose to realize a strongly interacting Fermi superfluid near a narrow Feshbach resonance using the recently discovered ``orbital Feshbach resonance.'' The orbital Feshbach resonance is a type of magnetic field tunable scattering resonance theoretically predicted and experimentally observed recently in the alkaline-earth-metal-like $^{173}\mathrm{Yb}$ atom. We first show that the orbital Feshbach resonance is a narrow resonance in energy, while it is hundreds Gauss wide in terms of magnetic field strength, taking the advantage that the magnetic moment difference between the open and closed channels is quite small. Therefore, this is an ideal platform for the experimental realization of a strongly interacting Fermi superfluid with narrow resonance. We further show that the transition temperature for the Fermi superfluid in this system, especially at the BCS side of the resonance, is even higher than that in a wide resonance, which is also due to the narrow character of this resonance. Our results will encourage experimental efforts to realize Fermi superfluid in the alikaline-earth-metal-like $^{173}\mathrm{Yb}$ system, the properties of which will be complementary to extensively studied Fermi superfluids nearby a wide resonance in alkali-metal $^{40}\mathrm{K}$ and $^{6}\mathrm{Li}$ systems.We propose to realize a strongly interacting Fermi superfluid near a narrow Feshbach resonance using the recently discovered ``orbital Feshbach resonance.'' The orbital Feshbach resonance is a type of magnetic field tunable scattering resonance theoretically predicted and experimentally observed recently in the alkaline-earth-metal-like $^{173}\mathrm{Yb}$ atom. We first show that the orbital Feshbach resonance is a narrow resonance in energy, while it is hundreds Gauss wide in terms of magnetic field strength, taking the advantage that the magnetic moment difference between the open and closed channels is quite small. Therefore, this is an ideal platform for the experimental realization of a strongly interacting Fermi superfluid with narrow resonance. We further show that the transition temperature for the Fermi superfluid in this system, especially at the BCS side of the resonance, is even higher than that in a wide resonance, which is also due to the narrow character of this resonance. Our results will encourage experimental efforts to realize Fermi superfluid in the alikaline-earth-metal-like $^{173}\mathrm{Yb}$ system, the properties of which will be complementary to extensively studied Fermi superfluids nearby a wide resonance in alkali-metal $^{40}\mathrm{K}$ and $^{6}\mathrm{Li}$ systems.

arXiv:1602.06513Physical Review ASep 9, 201636 citations

Emergent s -wave interactions in orbitally active quasi-two-dimensional Fermi gases

Colin J. Dale, K. G. S. Xie, Kiera Pond Grehan +3 more

The authors prepare a quasi-two-dimensional spin-polarized Fermi gas with orbital excitations and p-wave interactions enabled by a Feshbach resonance. Radio-frequency spectroscopy indicates $s$ -wave scattering symmetry in the plane, demonstrating how gapped orbital degrees of freedom can be used to control scattering symmetry in strongly confined ultracold gases.The authors prepare a quasi-two-dimensional spin-polarized Fermi gas with orbital excitations and p-wave interactions enabled by a Feshbach resonance. Radio-frequency spectroscopy indicates $s$-wave scattering symmetry in the plane, demonstrating how gapped orbital degrees of freedom can be used to control scattering symmetry in strongly confined ultracold gases.

arXiv:2408.00737Physical Review ANov 15, 20245 citations

Resonantly Interacting Fermi-Fermi Mixture of Dy161 and K40

Cornelis Ravensbergen, Elisa Soave, Vincent Le Corre +4 more

We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of ^{161}Dy and ^{40}K, we identify a broad Feshbach resonance centered at a magnetic field of 217 G. Hydrodynamic expansion profiles in the resonant interaction regime reveal a bimodal behavior resulting from mass imbalance. Lifetime studies on resonance show a suppression of inelastic few-body processes by orders of magnitude, which we interpret as a consequence of the fermionic nature of our system. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of ^{161}Dy and ^{40}K, we identify a broad Feshbach resonance centered at a magnetic field of 217 G. Hydrodynamic expansion profiles in the resonant interaction regime reveal a bimodal behavior resulting from mass imbalance. Lifetime studies on resonance show a suppression of inelastic few-body processes by orders of magnitude, which we interpret as a consequence of the fermionic nature of our system. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.

arXiv:1909.03424Physical Review LettersMay 22, 202045 citations

Observation of an Orbital Interaction-Induced Feshbach Resonance in Yb 173

M. Höfer, Luis Riegger, Francesco Scazza +6 more

We report on the experimental observation of a novel interorbital Feshbach resonance in ultracold (173)Yb atoms. This opens up the possibility of tuning the interactions between the (1)S(0) and (3)P(0) metastable state, both possessing zero total electronic angular momentum. The resonance is observed at experimentally accessible magnetic field strengths and occurs universally for all hyperfine state combinations. We characterize the resonance in the bulk via interorbital cross thermalization as well as in a three-dimensional lattice using high-resolution clock-line spectroscopy. Our measurements are well described by a generalized two-channel model of the orbital-exchange interactions.We report on the experimental observation of a novel interorbital Feshbach resonance in ultracold (173)Yb atoms. This opens up the possibility of tuning the interactions between the (1)S(0) and (3)P(0) metastable state, both possessing zero total electronic angular momentum. The resonance is observed at experimentally accessible magnetic field strengths and occurs universally for all hyperfine state combinations. We characterize the resonance in the bulk via interorbital cross thermalization as well as in a three-dimensional lattice using high-resolution clock-line spectroscopy. Our measurements are well described by a generalized two-channel model of the orbital-exchange interactions.

arXiv:1509.04257Physical Review LettersDec 21, 2015173 citations

Strongly Interacting Fermi-Fermi Mixture of

^{161}

Dy and

^{40}

We report on the realization of a Fermi-Fermi mixture of ultracold atoms that combines mass imbalance, tunability, and collisional stability. In an optically trapped sample of

^{161}

Dy and

^{40}

K, we identify a broad Feshbach resonance centered at a magnetic field of 218

\,

G. In the strongly interacting regime, we demonstrate hydrodynamic behavior in the expansion after release from the trap. Lifetime studies on resonance show that the fermionic nature of the system suppresses inelastic few-body processes by several orders of magnitude. The resonant mixture opens up intriguing perspectives for studies on novel states of strongly correlated fermions with mass imbalance.

^{173}\mathrm{Yb}

atom. We first show that the orbital Feshbach resonance is a narrow resonance in energy, while it is hundreds Gauss wide in terms of magnetic field strength, taking the advantage that the magnetic moment difference between the open and closed channels is quite small. Therefore, this is an ideal platform for the experimental realization of a strongly interacting Fermi superfluid with narrow resonance. We further show that the transition temperature for the Fermi superfluid in this system, especially at the BCS side of the resonance, is even higher than that in a wide resonance, which is also due to the narrow character of this resonance. Our results will encourage experimental efforts to realize Fermi superfluid in the alikaline-earth-metal-like

^{173}\mathrm{Yb}

system, the properties of which will be complementary to extensively studied Fermi superfluids nearby a wide resonance in alkali-metal

^{40}\mathrm{K}

and

^{6}\mathrm{Li}

systems.

The authors prepare a quasi-two-dimensional spin-polarized Fermi gas with orbital excitations and p-wave interactions enabled by a Feshbach resonance. Radio-frequency spectroscopy indicates

s

-wave scattering symmetry in the plane, demonstrating how gapped orbital degrees of freedom can be used to control scattering symmetry in strongly confined ultracold gases.