Efimov Effect in Ultracold Microwave-shielded Polar Molecules

Recent breakthroughs in microwave collisional shielding have enabled dramatic suppression of two-body loss in ultracold polar molecules by engineering long-range repulsive barriers in field-dressed interaction potentials [1]. This opens a new pathway to study few-body universality in ultracold polar molecules where rapid short-range losses have historically made such studies difficult. We present a quantum theory of three-body scattering for microwave-dressed polar molecules using the adiabatic hyperspherical formalism, where the two-body interactions are defined using an anisotropic effective potential [2] and investigate the emergence of Efimov physics in the shielded regime. Within this framework, we pin down universal signatures in the spectrum— Efimov resonance locations, trimer binding energies, and three-body recombination rates—and track how they evolve with the two-body scattering length.

References

[1] Karman, T., Bigagli, N., Yuan, W., Zhang, S., Stevenson, I., & Will, S. (2025). Double microwave shielding. PRX Quantum, 6(2), 020358.

[2] Deng, F., Hu, X., Jin, W. J., Yi, S., & Shi, T. (2025). Two-and many-body physics of ultracold molecules dressed by dual microwave fields. Nature Communications.