Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots

Abstract

We study a vertical double quantum dot (DQD) in a Si/Si${}_{1-x}$Ge${}_x$/Si double-well heterostructure for full electrical control of electron Loss-DiVincenzo (LD) spin qubits, using realistic device modeling and numerical simulations. Due to the emerging spin-orbit interaction in the DQD, as well as strain from the gate electrodes, small (percentage range) but finite $g$ tensor variations emerge. In addition, we find a large valley splitting, on the order of $E_v\sim 250\mu$eV. As a result, multiple avenues for fast electrical single qubit rotations emerge. An ac electric field gives rise to electric dipole spin resonance (EDSR), while electron spin resonance (ESR) in the presence of an ac magnetic field can be electrically controlled by local gates due to varying $g$ factors in DQDs. We also show that shuttling between neighboring dots, in vertical and horizontal direction, results in ultrafast single qubit gates of less than a nanosecond. Remarkably, this DQD architecture completely eliminates the need for micromagnets, significantly facilitating the scalability of LD spin qubits in semiconductor foundries.

4 pages, 4 figures

References in corpus (39)

• Coherent control of a single electron spin with electric fields
• Semiconductor Spin Qubits
• Computing with spin qubits at the surface code error threshold
• Universal control of a six-qubit quantum processor in silicon
• Two-qubit silicon quantum processor with operation fidelity exceeding 99%
• A hole spin qubit in a fin field-effect transistor above 4 kelvin
• A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
• Charge-noise spectroscopy of Si/SiGe quantum dots via dynamically-decoupled exchange oscillations
• Strong coupling between a photon and a hole spin in silicon
• A single hole spin with enhanced coherence in natural silicon
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Operating semiconductor quantum processors with hopping spins
• Atomic fluctuations lifting the energy degeneracy in Si/SiGe quantum dots
• SiGe quantum wells with oscillating Ge concentrations for quantum dot qubits
• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Site-selective quantum control in an isotopically enriched 28Si/SiGe quadruple quantum dot
• Dispersive readout of valley splittings in cavity-coupled silicon quantum dots
• Charge detection in an array of CMOS quantum dots
• An electrically driven spin qubit based on valley mixing
• Valley splittings in Si/SiGe quantum dots with a germanium spike in the silicon well
• A 300 mm foundry silicon spin qubit unit cell exceeding 99% fidelity in all operations
• Ultra-high mobility two-dimensional electron gas in a SiGe/Si/SiGe quantum well
• Singlet-Triplet Relaxation in Two-electron Silicon Quantum Dots
• Low disorder and high valley splitting in silicon
• How valley-orbit states in silicon quantum dots probe quantum well interfaces
• Nonlinear response and crosstalk of electrically driven silicon spin qubits
• Low dephasing and robust micromagnet designs for silicon spin qubits
• Enhanced Valley Splitting in Si Layers with Oscillatory Ge Concentration
• High-fidelity spin qubit shuttling via large spin-orbit interaction
• Spin-orbit enhancement in Si/SiGe heterostructures with oscillating Ge concentration
• Valley-Free Silicon Fins Caused by Shear Strain
• Valley splitting in silicon from the interference pattern of quantum oscillations
• Coupled vertical double quantum dots at single-hole occupancy
• Theory of Valley Splitting in Si/SiGe Spin-Qubits: Interplay of Strain, Resonances and Random Alloy Disorder
• Operating semiconductor qubits without individual barrier gates
• Optimisation of electrically-driven multi-donor quantum dot qubits
• Coherence of a field-gradient-driven singlet-triplet qubit coupled to many-electron spin states in 28Si/SiGe
• Valley Splitting Correlations Across a Silicon Quantum Well Containing Germanium
• Valley physics in the two bands $\mathbf{k}\cdot \mathbf{p}$ model for SiGe heterostructures and spin qubits