In some embodiments, when the openings at the pier, approach bridge, and bridge top portions are through, a complete fully-enclosed air bridge is divided into a plurality of separated air bridges. Separated air bridges indicate that the air bridges are not connected to each other, and each are an independent air bridge. A fully-enclosed air bridge means that a series of air bridges are connected to each other by components to form an air bridge as a whole.

In the related art, the methods for fabricating a superconducting air bridge are mainly glue-based methods. That is, a photoresist is fabricated into an arch shape by using the reflow property of the photoresist. A material is then deposited on a top of the photoresist. Secondary coating, exposure, and development are performed. A protective glue is covered at a position of an air bridge structure. The material at the remaining positions is etched off. Finally, all of the photoresist is removed with a glue remover to obtain an air bridge.

However, many process steps are included for the superconducting quantum FC. To reduce the impact of the process on a junction device serving as a bit, the air bridge structure is fabricated in the early stage of the FC process, which means that it is necessary to ensure that the air bridge is not damaged during many subsequent processes. Therefore, it is necessary to use a non-photoresist bridge brace, and keep the bridge brace in the subsequent processes until the bridge brace is released before the final FC process. However, in the method, for a common fully-enclosed air bridge in a superconducting circuit, because of the long longitudinal length of the bridge, when the bridge brace is released, it is likely that a large amount of bridge brace residue is left inside a bridge hole, seriously affecting the quality of the device.