A Magic Wavelength Trap for Ultracold KRb

Ultracold dipolar molecules provide tunable long-range, anisotropic interactions that enable the study of a multitude of spin-motion models, where spin is encoded in two rotational states of the molecule. To explore the novel quantum phases and dynamics predicted for such systems [1,2], long rotational coherence times are crucial. While one-body dephasing can be suppressed through dynamical decoupling [1,2], magic traps offer native dephasing suppression by minimizing the differential polarizability between the two involved states.

Here we present the development of a magic wavelength trap detuned from the X-b transition of 40K87Rb. Rotationally magic optical traps have been realized for 87Rb133Cs [3] and 23Na40K [4]. Compared to magic angle traps [5], such traps allow for more flexible trap geometries. Our preliminary work confirms the existence of a magic wavelength around 30 GHz detuned from the X-b transition. By implementing a magic trap, we expect to permit second-scale coherence times which will enhance future studies of many-body spin dynamics.

[1] A. N. Carroll, et al., Science 388, 6745 (2025)

[2] C. Miller, et al., Nature 633, 332–337 (2024)

[3] P.D. Gregory, et al., Nature Physics 20, 415-421 (2024)

[4] R. Bause, et al., PRL 125, 023201 (2020)

[5] B. Neyenhuis, et al., Phys. Rev. Lett. 109, 230403 (2012)