Berlin 2024 – scientific programme

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QI: Fachverband Quanteninformation

QI 18: Poster II

QI 18.23: Poster

Wednesday, March 20, 2024, 11:00–14:30, Poster A

Microwave-shielding of ultracold polar molecules - from evaporation to field-linked tetramers — •Sebastian Eppelt¹, Shrestha Biswas¹, Xingyan Chen¹, Xinyu Luo¹, Timon Hilker¹, and Immanuel Bloch^1,2 — ¹Max-Planck-Institute of Quantum Optics, Garching, Germany — ²Ludwig-Maximilans-University, Munich, Germany

Thanks to their strong electric dipole moments and rich internal structure, ultracold polar molecules are a promising platform for realizing exotic quantum matter, for implementing quantum information schemes and for performing precision measurements. In many of these applications, samples of interacting molecular need to be prepared in the quantum-degenerate regime. For a long time, employing evaporative cooling via elastic collisions has been prevented by intrinsically unstable two-body collisions at short range. Protecting molecules against such collisions can be achieved by engineering a repulsive barrier using a blue-detuned, circularly polarized microwave field which couples two rotational states. Here, we demonstrate how microwave shielding can be employed to evaporatively cool a fermionic, 3D gas of ²³Na⁴⁰K well below T_F. Furthermore, we show how to realize a novel kind of scattering resonances which can be used to tune the interactions between molecules by manipulating the microwave field. These universal field-linked resonances arise due to the existence of long-lived, tetratomic bound states in the intermolecular potential. Lastly, we present our advances in creating and observing these bound states, whose properties agree very well with parameter-free theory calculations.

Keywords: Quantum Simulation; Long-Range Interaction; Dipolar Gases; Molcular Physics; Quantum Many-Body Systems