Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots

Abstract

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

13 pages, 12 figures. accepted for publication by Physical Review Applied

References in corpus (9)

• Excited-state spectroscopy on a nearly-closed quantum dot via charge detection
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Pauli Blockade in Silicon Quantum Dots with Spin-Orbit Control
• Electric field effect on electron spin splitting in SiGe/Si quantum wells
• Tetragonal and trigonal deformations in zinc-blende semiconductors : a tight-binding point of view
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Cited by in corpus (33)

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• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
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• Strong electron-electron interactions in Si/SiGe quantum dots
• Coherent control and spectroscopy of a semiconductor quantum dot Wigner molecule
• Low disorder and high valley splitting in silicon
• How valley-orbit states in silicon quantum dots probe quantum well interfaces
• Coherent spin-valley oscillations in silicon
• Mapping of valley-splitting by conveyor-mode spin-coherent electron shuttling
• Probing the Spatial Variation of the Inter-Valley Tunnel Coupling in a Silicon Triple Quantum Dot
• Utilizing multimodal microscopy to reconstruct Si/SiGe interfacial atomic disorder and infer its impacts on qubit variability
• Wafer-scale low-disorder 2DEG in ${}^{28}$Si/SiGe without an epitaxial Si cap
• Interface and electromagnetic effects in the valley splitting of Si quantum dots
• Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures
• Coherent control of a triangular exchange-only spin qubit
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• Coupling conduction-band valleys in SiGe heterostructures via shear strain and Ge concentration oscillations
• Atomistic compositional details and their importance for spin qubits in isotope-purified silicon-germanium quantum wells
• Measurement of tunnel coupling in a Si double quantum dot based on charge sensing
• Valley-Free Silicon Fins Caused by Shear Strain
• Valley splitting depending on the size and location of a silicon quantum dot
• Optimal control of a cavity-mediated iSWAP gate between silicon spin qubits
• Local laser-induced solid-phase recrystallization of phosphorus-implanted Si/SiGe heterostructures for contacts below 4.2 K
• Gate reflectometry in dense quantum dot arrays
• Charge-noise resilience of two-electron quantum dots in Si/SiGe heterostructures
• Dissipation and gate timing errors in SWAP operations of qubits
• Valley Splitting Correlations Across a Silicon Quantum Well Containing Germanium
• Proposal for a cavity-induced measurement of the exchange coupling in quantum dots
• The effects of alloy disorder on strongly-driven flopping mode qubits in Si/SiGe
• Towards Utilizing Scanning Gate Microscopy as a High-Resolution Probe of Valley Splitting in Si/SiGe Heterostructures
• Measuring and correcting nanosecond pulse distortions in quantum-dot spin qubits