Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures

Abstract

Silicon can be isotopically enriched, allowing for the fabrication of highly coherent semiconductor spin qubits. However, the conduction band of bulk Si exhibits a six-fold valley degeneracy, which may adversely impact the performance of silicon quantum devices. To date, the spatial characterization of valley states in Si remains limited. Moreover, techniques for probing valley states in functional electronic devices are needed. We describe here a cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at mK temperatures. The microscope is based on the Pan-walker design, with coarse positioning piezo stacks and a fine scanning piezo tube. A tungsten microscope tip is attached to a tuning fork for active control of the tip-to-sample distance. To reduce vibration noise from the pulse tube cooler, we utilize both active and passive vibration isolation mechanisms, and achieve a root-mean-square noise in $z$ of $\sim$ 2 nm. Our microscope is designed to characterize fully functioning Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices. As a proof of concept, we use the microscope to manipulate the charge occupation of a Si quantum dot, opening up a range of possibilities for the exploration of quantum devices and materials.

References in corpus (47)

• Quantum Computation with Quantum Dots
• Spins in few-electron quantum dots
• Observation of Electron-Hole Puddles in Graphene Using a Scanning Single Electron Transistor
• Silicon Quantum Electronics
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• A programmable two-qubit quantum processor in silicon
• Quantum CNOT Gate for Spins in Silicon
• Coherent Branched Flow in a Two-Dimensional Electron Gas
• A Coherent Spin-Photon Interface in Silicon
• Mapping the twist angle and unconventional Landau levels in magic angle graphene
• Imaging viscous flow of the Dirac fluid in graphene
• Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
• Scalable gate architecture for densely packed semiconductor spin qubits
• Shuttling a single charge across a one-dimensional array of silicon quantum dots
• Imaging currents in HgTe quantum wells in the quantum spin Hall regime
• Controllable valley splitting in silicon quantum devices
• Silicon qubit fidelities approaching incoherent noise limits via pulse engineering
• A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
• Benchmarking Gate Fidelities in a Si/SiGe Two-Qubit Device
• Imaging Fractal Conductance Fluctuations and Scarred Wave Functions in a Quantum Billiard
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• Spatially resolved manipulation of single electrons in quantum dots using a scanned probe
• Interface roughness, valley-orbit coupling and valley manipulation in quantum dots
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• Imaging work and dissipation in the quantum Hall state in graphene
• Large, tunable valley splitting and single-spin relaxation mechanisms in a Si/Si${}_x$Ge${}_{1-x}$ quantum dot
• High Resolution Valley Spectroscopy of Si Quantum Dots
• Imaging a Single-Electron Quantum Dot
• Quantifying error and leakage in an encoded Si/SiGe triple-dot qubit
• Single-Spin Relaxation in a Synthetic Spin-Orbit Field
• Valley dependent anisotropic spin splitting in silicon quantum dots
• Site-selective quantum control in an isotopically enriched 28Si/SiGe quadruple quantum dot
• Investigation of Mobility Limiting Mechanisms in Undoped Si/SiGe Heterostructures
• Absorptive pinhole collimators for ballistic Dirac fermions in graphene
• Valley splittings in Si/SiGe quantum dots with a germanium spike in the silicon well
• Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots
• Force-gradient-induced mechanical dissipation of quartz tuning fork force sensors used in atomic force microscopy
• The critical role of substrate disorder in valley splitting in Si quantum wells
• Design of a scanning gate microscope in a cryogen-free dilution refrigerator
• Effects of Interface Steps on the Valley Orbit coupling in a Si/SiGe quantum dot
• Imaging doubled shot noise in a Josephson scanning tunneling microscope
• Spin-Blockade Spectroscopy of Si/SiGe Quantum Dots
• Probing the Spatial Variation of the Inter-Valley Tunnel Coupling in a Silicon Triple Quantum Dot
• Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells
• Spatial and energy resolution of electronic states by shot noise
• Induced quantum dot probe for material characterization

Cited by in corpus (8)

• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Strategies for enhancing spin-shuttling fidelities in Si/SiGe quantum wells with random-alloy disorder
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• 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
• 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