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"The measurements reveal that the interface consists of a 'suboxide' layer nestled between the periodically ordered tantalum atoms and the fully disordered amorphous tantalum oxide. Within this suboxide layer, only a few oxygen atoms are integrated into the tantalum crystal lattice," Zhu said.

By assessing the thermodynamic stability, structure, and electronic property changes of the tantalum films during oxidation, the scientists concluded that while the fully oxidized amorphous layer acts as an insulator, the suboxide layer retains features of a metal.

With the presence of both fully oxidized tantalum and a suboxide layer, the scientists wanted to understand which part is most responsible the loss of coherence in qubits made of this superconducting material.

But because the suboxide layer is still crystalline, "it may not be as bad as people were thinking," Liu said.

Then again, he noted, because the suboxide layer has some metallic characteristics, it could cause other problems.