Long-lived ultracold molecules via double microwave shielding

We introduce double microwave shielding as a method to suppress collisional losses. When pairs of ultracold molecules collide, they are found to be lost regardless of the molecular species. Dressing the molecules with a single circularly polarized microwave field suppresses this two-body loss. However, we observe that as two-body losses are suppressed, three-body loss appears [1]. We demonstrate that three-body loss can be suppressed by adding an orthogonal linearly polarized field that cancels the long-range dipole-dipole interactions [2]. We find this method simultaneously reduces two- and three-body loss by more than a factor of a thousand. In addition to reducing losses, double microwave shielding also enables the wide tuning of dipolar interactions in a while retaining long lifetimes. This is critical groundwork on the way to preparing many-body phases of dipolar NaCs molecules, such as BECs, or quantum droplets.

[1] “Collisionally stable gas of bosonic dipolar ground state molecules,” Bigagli, N., Warner, C., Yuan, W., Zhang, S., Stevenson, I., Karman, T., Will, S., Nature Phys., 19, 1579-1584 (2023).

[2] “Observation of Bose-Einstein condensation in a gas of dipolar molecules,” Bigagli, N., Yuan, W., Zhang, S., Bulatovic, B., Karman, T., Stevenson, I., Will, S., arXiv:2312.10965 (2023).