Fig. 2: Stark tone implementation.
a Schematic of qubit T1 response to shift in qubit frequency (red traces), at different times, t. The qubit frequency is tuned by an amount Δωq by an off-resonant tone placed ∣Δqs∣ above the qubit frequency ωq. The dependence of the frequency shift on the off-resonant tone amplitude Ωs is depicted by the blue trace. The T1 dips are indicative of the qubit coming into resonance with a strongly coupled TLS, at the frequency ωTLS. The TLS frequency shifts in time due to spectral diffusion, schematically indicated by changes in the T1 dips at different time snapshots. b Schematic of a Ramsey pulse sequence used to calibrate Δωq as a function of Ωs (top); and (bottom) schematic pulse sequence for the relaxation time spectroscopy. For each Ωs (i.e., Δωq), the \(\left|1\right\rangle\) occupation is measured at a fixed time (i.e., τ = 50 μs in this work). c An illustrative case of the 01 transition dependence on ωs for constant Ωs. The 01 qubit frequency, ωq + Δωq, uses an unperturbed frequency of ωq = 5.0 GHz and an anharmonicity of δq = −340 MHz. The locations of the unperturbed 01 and 12 transitions are shown as vertical lines overlaid with 5 MHz offsets to make their locations more visible on the figure. Negative and positive qubit shifts can be produced and large shifts can be induced depending on Δqs. d Measured Δωq as a function of normalized DAC amplitude, Ωs using the AC Stark shifted Ramsey technique. Solid line is a quadratic fit functionally consistent with a perturbative model.
