Figure 1
From: Magnetic flux noise in superconducting qubits and the gap states continuum
(A) The complex band structure of the unperturbed CsCl insulator (\(\Delta =\) 0 eV) in the complex plane of \(\vartheta\) for \({\mathrm{Re}}[\vartheta ]\in \langle -1,1\rangle \cap {\mathrm{Im}}[\vartheta ]\in \langle 0,1\rangle\). (B) The complex band structure of the unperturbed CsCl insulator projected on the Re[k] (left panel) and Im[k] axes (right panel). The propagating, edge and gap states are distinguished by the blue, green and red color, respectively. Moreover, the zero energy level is set at the top of the valence band.
