Reactive near-field subwavelength microwave imaging with a non-invasive Rydberg probe

Non-invasive microwave field imaging—accurately mapping field distributions without perturbing them—is essential in areas such as aerospace engineering, biomedical imaging, and integrated-circuit diagnostics. Conventional metal probes, however, inevitably perturb reactive near fields: they act as strong scatterers that drive induced currents and secondary radiation, remap evanescent components, and thereby degrade both accuracy and spatial resolution, particularly in the reactive near-field regime that is most relevant to these applications. Here we demonstrate low-perturbation reactive-near-field microwave imaging using quantum-enabled, all-optical Rydberg-atom electrometry, realized with a compact, non-invasive, single-ended fiber-integrated Rydberg probe engineered to minimize field disturbance. A dual-wire benchmark demonstrates a lateral resolving capability of approximately 0.62 mm ( λ /56), and the measured horn- and chip-antenna field distributions are more consistent with full-wave simulations than those acquired with conventional metallic probes, supporting the low-perturbation character of the Rydberg probe. Because the atomic sensor is intrinsically isotropic, the same device can faithfully image multi-dimensional field structures without orientation-dependent calibration. Our results, therefore, establish a general, non-invasive route to high-accuracy, subwavelength reactive near-field microwave imaging, with particular promise for applications such as chip-defect detection and integrated-circuit diagnostics, where even small perturbations by the probe can mask the underlying physics of interest.