Amplitude and polarization control for microwave-driven tunneling in Rydberg-atom synthetic dimensions

Tunneling in a Rydberg-atom synthetic dimension [1] is realized by microwave Rabi couplings between Rydberg states. In experiments using metal chambers, microwaves undergo internal reflections, leading to large intensity variations across the spectrum (here, 16-24 GHz) and a lack of polarization control. These complicate experimental control of the tunneling parameter and drive unwanted, off-resonant transitions to neighboring states, thereby adversely affecting coherence in quantum simulations. To suppress such effects, large-optical-access viewports are used on a new apparatus to allow the clear passage of microwaves. Here, we describe the performance of this setup, evaluated by driving Rydberg-Rydberg transitions and measuring their coherence times and coupling strengths using Rabi oscillations. The polarization purity is probed by driving single-photon S-P and two-photon S-D transitions in a magnetic field.

[1] Y. Lu, et al., Phys. Rev. A 110, 023318 (2024)