Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Si</mml:mi></mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Si</mml:mi></mml:math> - <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Ge</mml:mi></mml:math> Quantum Dots

Silicon-quantum-dot qubits must contend with low-lying valley excited states that are sensitive functions of the quantum-well heterostructure and disorder; quantifying maximizing energies these critical to improving device performance. We describe a spectroscopic method for probing in isolated $\mathrm{Si}$/$\mathrm{Si}$-$\mathrm{Ge}$ double quantum dots using standard baseband pulsing techniques, easing extraction energy spectra multiple-dot devices. use this measure dozens excited-state spanning multiple wafers, dots, orbital states, which crucial evaluating dependence splitting on well width other epitaxial conditions. Our results suggest narrower wells can be beneficial increasing splittings, but effect confounded by variations growth fabrication These underscore importance valley-splitting measurements guiding development $\mathrm{Si}$ qubits.