Figure 2. LZS interference in a phase qubit coupled to two TLSs.

(a) The population of |1 measured immediately (a few ns) after the triangular flux pulse is plotted as a function of the width and amplitude of the triangular flux bias waveform. The oblique dotted lines are lines of constant characteristic sweeping rates, ν₁ and ν₂, defined in the text. The white circles mark the 'hot spots', where the interference fringes generated by M₂ tend to fade out and the interference fringes generated by M₁ dominate. (b, c) Analytically calculated constructive interference strips in regions I and II, respectively. The horizontal and vertical dotted lines indicate the corresponding locations of interference strips. (b, c) have the same axis labels as (a). (d) Schematic of generating LZS interference with tunable beam splitters in a phase qubit coupled to two TLSs. M₁ and M₂ correspond to the TLSs with smaller and larger avoided crossings in Figure 1d, respectively.