Samples of ultracold, polar molecules (UPMs) can provide access to new regimes in many phenomena [1]. Ultracold temperatures allow trapping, and polarity can be used to engineer large, anisotropic, and tunable interactions between molecules. These features make UPMs attractive as qubits for quantum computation, as building blocks for novel many-body systems, and for the study of chemistry in the ultracold regime. UPMs also could be used as uniquely sensitive probes of phenomena beyond the Standard Model of particle physics.Samples of ultracold, polar molecules (UPMs) can provide access to new regimes in many phenomena [1]. Ultracold temperatures allow trapping, and polarity can be used to engineer large, anisotropic, and tunable interactions between molecules. These features make UPMs attractive as qubits for quantum computation, as building blocks for novel many-body systems, and for the study of chemistry in the ultracold regime. UPMs also could be used as uniquely sensitive probes of phenomena beyond the Standard Model of particle physics.

Frontiers in OpticsJan 1, 20050 citations

Controlled Collisions between Ultracold Polar Molecules

William G. Tobias, Jun-Ru Li, Kyle Matsuda +3 more

Bulletin of the American Physical SocietyJun 3, 20210 citations

Effective anisotropic interaction potentials for pairs of ultracold molecules shielded by a static electric field

Bijit Mukherjee, Luis Santos, Jeremy M. Hutson

Abstract Quantum gases of ultracold polar molecules have novel properties because of the strong dipolar forces between molecules. Current experiments shield the molecules from destructive collisions by engineering long-range repulsive interactions using microwave or static electric fields. These shielding methods produce interaction potentials with large repulsive cores that are not well described with contact potentials. In this paper we explore the anisotropic interaction potentials that arise for pairs of polar molecules shielded with static electric fields. We derive computationally inexpensive approximations for the potentials that are suitable for use in calculations of many-body properties. The interaction potentials for molecules shielded with static fields are substantially different from those that arise from microwave shielding and will produce quite different many-body physics.Abstract Quantum gases of ultracold polar molecules have novel properties because of the strong dipolar forces between molecules. Current experiments shield the molecules from destructive collisions by engineering long-range repulsive interactions using microwave or static electric fields. These shielding methods produce interaction potentials with large repulsive cores that are not well described with contact potentials. In this paper we explore the anisotropic interaction potentials that arise for pairs of polar molecules shielded with static electric fields. We derive computationally inexpensive approximations for the potentials that are suitable for use in calculations of many-body properties. The interaction potentials for molecules shielded with static fields are substantially different from those that arise from microwave shielding and will produce quite different many-body physics.

arXiv:2507.03164New Journal of PhysicsSep 1, 20254 citations

Controlled symmetry breaking of the Fermi surface in ultracold polar molecules

Shrestha Biswas, Sebastian Eppelt, Weikun Tian +6 more

Long-range anisotropic dipole-dipole interactions between ultracold polar molecules are predicted to drive exotic quantum phases, yet direct many-body signatures of these interactions in degenerate Fermi gases have remained elusive. Here, we report the observation of an interaction-induced controlled deformation of the Fermi surface, providing a clear many-body signature in a deeply degenerate Fermi gas of $^{23}\text{Na}^{40}\text{K}$ molecules. Using double microwave (MW) shielding, we prepare $8 \times 10^3$ molecules at $0.23(1)$ times the Fermi temperature, achieving a three-fold suppression of inelastic losses compared to single MW shielding while preserving strong elastic dipolar scattering. We observe Fermi surface deformations of up to $7\,\%$ , more than two times larger than those observed in magnetic atoms, despite operating at two orders of magnitude lower densities. Crucially, we demonstrate continuous tuning of the interaction potential from axial U(1) to biaxial C $_{2}$ symmetry, directly imprinting this geometry onto the Fermi surface. We find excellent agreement between our experimental results and parameter-free Hartree-Fock theory. These results establish MW-shielded polar molecules as a highly tunable platform for exploring strongly correlated dipolar Fermi matter and offer a promising path towards topological superfluidity.Long-range anisotropic dipole-dipole interactions between ultracold polar molecules are predicted to drive exotic quantum phases, yet direct many-body signatures of these interactions in degenerate Fermi gases have remained elusive. Here, we report the observation of an interaction-induced controlled deformation of the Fermi surface, providing a clear many-body signature in a deeply degenerate Fermi gas of $^{23}\text{Na}^{40}\text{K}$ molecules. Using double microwave (MW) shielding, we prepare $8 \times 10^3$ molecules at $0.23(1)$ times the Fermi temperature, achieving a three-fold suppression of inelastic losses compared to single MW shielding while preserving strong elastic dipolar scattering. We observe Fermi surface deformations of up to $7\,\%$, more than two times larger than those observed in magnetic atoms, despite operating at two orders of magnitude lower densities. Crucially, we demonstrate continuous tuning of the interaction potential from axial U(1) to biaxial C$_{2}$ symmetry, directly imprinting this geometry onto the Fermi surface. We find excellent agreement between our experimental results and parameter-free Hartree-Fock theory. These results establish MW-shielded polar molecules as a highly tunable platform for exploring strongly correlated dipolar Fermi matter and offer a promising path towards topological superfluidity.

cond-mat.quant-gasCross-listedarXiv:2602.22447Feb 27, 20260 citations

Understanding ultracold polar molecules

Paul S. Julienne

Bulletin of the American Physical SocietyMay 23, 20090 citations

Formation of Ultracold Polar Molecules

Elizabeth Juarros, Robin Côté, K. Kirby

APSMay 1, 20020 citations

^{23}\text{Na}^{40}\text{K}

molecules. Using double microwave (MW) shielding, we prepare

8 \times 10^3

molecules at

0.23(1)

times the Fermi temperature, achieving a three-fold suppression of inelastic losses compared to single MW shielding while preserving strong elastic dipolar scattering. We observe Fermi surface deformations of up to

7\,\%

, more than two times larger than those observed in magnetic atoms, despite operating at two orders of magnitude lower densities. Crucially, we demonstrate continuous tuning of the interaction potential from axial U(1) to biaxial C

_{2}

symmetry, directly imprinting this geometry onto the Fermi surface. We find excellent agreement between our experimental results and parameter-free Hartree-Fock theory. These results establish MW-shielded polar molecules as a highly tunable platform for exploring strongly correlated dipolar Fermi matter and offer a promising path towards topological superfluidity.