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In microchips, wires usually lie flat on the surface, like rails on the ground. But sometimes one wire needs to leap over another without touching it. For that, engineers build air bridges — thin metal arches suspended above the chip.

Previously, such a bridge was assembled in several stages: deposit a layer, expose it, etch it, repeat. Each stage is a chance to mess something up. The new work shows that a single pass of the electron beam suffices. The beam draws the entire bridge at once, and then the wafer is gently heated, and the metal bends itself into a smooth arc, like a sheet of paper curling over a flame.

They tested it on quantum chips: the bridges don't interfere with the signal, but they do shield it from unwanted noise. The time during which a quantum bit retains its phase grew by a factor of two and a half. That means quantum computers will be able to compute longer without errors.

So one of the most finicky steps in chip fabrication has turned into a simple print job. Fewer steps mean less waste and cheaper future devices.

Original abstract

as written by the authors arXiv:2601.16416

Airbridges are essential for creating high-performance, low-parasitic interconnects in integrated circuits and quantum devices. Conventional multi-step fabrication methods hinder miniaturization and introduce process-related defects. We report a simplified process for fabricating nanoscale airbridges using only a single electron-beam lithography step. By optimizing a multilayer resist stack with a triple-exposure-dose scheme and a thermal reflow step, we achieve smooth, suspended metallic bridges with sub-200-nm features that exhibit robust mechanical stability. Fabricated within a gradiometric SQUID design for superconducting transmon qubits, these airbridges introduce no measurable additional loss in the relaxation time $$T_1$$, while enabling a 2.5-fold enhancement of the dephasing time $$T_2^*$$. This efficient method offers a practical route toward integrating high-performance three-dimensional interconnects in advanced quantum and nano-electronic devices.