Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot

Abstract

Conventional quantum transport methods can provide quantitative information on spin, orbital, and valley states in quantum dots, but often lack spatial resolution. Scanning tunneling microscopy, on the other hand, provides exquisite spatial resolution of the local electronic density of states, but often at the expense of speed. Working to combine the spatial resolution and energy sensitivity of scanning probe microscopy with the speed of microwave measurements, we couple a metallic probe tip to a Si/SiGe double quantum dot that is integrated with a local charge detector. We first demonstrate that a dc-biased tip can be used to change the charge occupancy of the double dot. We then apply microwave excitation through the scanning tip to drive photon-assisted tunneling transitions in the double dot. We infer the double dot energy level diagram from the frequency and detuning dependence of the photon-assisted tunneling resonance condition. These measurements allow us to resolve $\sim$65 $\mu$eV excited states, an energy scale consistent with typical valley splittings in Si/SiGe. Future extensions of this approach may allow spatial mapping of the valley splitting in Si devices, which is of fundamental importance for spin-based quantum processors.

References in corpus (5)

• Scalable gate architecture for densely packed semiconductor spin qubits
• A double-dot quantum ratchet driven by an independently biased quantum point contact
• Imaging a 1-electron InAs quantum dot in an InAs/InP nanowire
• Quantum state readout of individual quantum dots by electrostatic force detection
• Spatial mapping and manipulation of two tunnel-coupled quantum dots

Cited by in corpus (10)

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• Valleytronic full configuration-interaction approach: An application to the excitation spectra of Si double-dot qubits
• In-situ scanning gate imaging of individual two-level material defects in live superconducting quantum circuits
• Dispersive readout of a silicon quantum device using an atomic force microscope-based rf gate sensor
• Second Quantization: Gating a Quantum Dot Through the Sequential Removal of Single Electrons from a Nanoscale Floating Gate
• Towards Utilizing Scanning Gate Microscopy as a High-Resolution Probe of Valley Splitting in Si/SiGe Heterostructures
• Supercurrent modulation in InSb nanoflag-based Josephson junctions by scanning gate microscopy
• Signatures of Majorana bound states in scanning gate microscopy of hybrid nanowires