Identification of soft modes in amorphous Al${}_2$O${}_3$ via first-principles

Amorphous Al${}_2$O${}_3$ is a fundamental component of modern superconducting qubits. While amphorphous oxides offer distinct advantages, such as directional isotropy and a consistent bulk electronic gap, in realistic systems these compounds support two-level systems (TLSs) which couple to the qubit, expediting decoherence. In this work, we perform a first-principles study of amorphous Al${}_2$O${}_3$ and identify low-energy modes in the electronic and phonon spectra as a possible origin for TLSs.