The effects of alloy disorder on strongly-driven flopping mode qubits in Si/SiGe

Abstract

In Si quantum dot systems, large magnetic field gradients are needed to implement spin rotations via electric dipole spin resonance (EDSR). By increasing the effective electron dipole, flopping mode qubits can provide faster gates with smaller field gradients. Moreover, operating in the strong-driving limit can reduce their sensitivity to charge noise. However, alloy disorder in Si/SiGe heterostructures randomizes the valley energy splitting and the valley phase difference between dots, enhancing the probably of valley excitations while tunneling between the dots, and opening a leakage channel. In this work, we analyze the performance of flopping mode spin qubits in the presence of charge noise and alloy disorder, and we optimize these qubits for a variety of valley configurations, in both weak and strong charge-noise regimes. When the charge noise is weak, high fidelity qubits can be implemented across a wide range of valley parameters, provided the electronic pulse is fine-tuned for a given valley configuration. When the charge noise is strong, high-fidelity pulses can still be engineered, provided the valley splittings in each dot are relatively large and the valley phase difference is relatively small. We analyze how charge noise-induced fluctuations of the inter-dot detuning, as well as small shifts in other qubit parameters, impact qubit fidelities. We find that strongly driven pulses are less sensitive to detuning fluctuations but more sensitive to small shifts in the valley parameters, which can actually dominate the qubit infidelities in some regimes. Finally, we discuss schemes to tune devices away from poor-performing configurations, enhancing the scalability of flopping-mode-based qubit architectures.

arXiv comment29 pages, 20 figures

References in corpus (47)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Quantum Computation with Quantum Dots
• Silicon Quantum Electronics
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• Semiconductor Spin Qubits
• Computing with spin qubits at the surface code error threshold
• Fast universal quantum control above the fault-tolerance threshold in silicon
• Two-qubit silicon quantum processor with operation fidelity exceeding 99%
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Low-frequency charge noise in Si/SiGe quantum dots
• A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
• Low-frequency spin qubit detuning noise in highly purified ${}^{28}$Si/SiGe
• Charge-noise spectroscopy of Si/SiGe quantum dots via dynamically-decoupled exchange oscillations
• Dephasing of Si spin qubits due to charge noise
• Electrically Protected Valley-Orbit Qubits in Silicon
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Exchange coupling in silicon quantum dots: Theoretical considerations for quantum computation
• 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
• Atomic fluctuations lifting the energy degeneracy in Si/SiGe quantum dots
• Tunable singlet-triplet splitting in a few-electron Si/SiGe quantum dot
• SiGe quantum wells with oscillating Ge concentrations for quantum dot qubits
• Single-Spin Relaxation in a Synthetic Spin-Orbit Field
• Valley dependent anisotropic spin splitting in silicon quantum dots
• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Electric-field control and noise protection of the flopping-mode spin qubit
• Flopping-mode electric dipole spin resonance
• Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots
• Low disorder and high valley splitting in silicon
• Modelling semiconductor spin qubits and their charge noise environment for quantum gate fidelity estimation
• The critical role of substrate disorder in valley splitting in Si quantum wells
• Geometrical Formalism for Dynamically Corrected Gates in Multiqubit Systems
• How valley-orbit states in silicon quantum dots probe quantum well interfaces
• Dressed photon-orbital states in a quantum dot: Inter-valley spin resonance
• Mapping of valley-splitting by conveyor-mode spin-coherent electron shuttling
• Interplay of charge noise and coupling to phonons in adiabatic electron transfer between quantum dots
• Robust quantum gates using smooth pulses and physics-informed neural networks
• Strategies for enhancing spin-shuttling fidelities in Si/SiGe quantum wells with random-alloy disorder
• Interface and electromagnetic effects in the valley splitting of Si quantum dots
• Flopping-mode spin qubit in a Si-MOS quantum dot
• Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures
• Coupling conduction-band valleys in SiGe heterostructures via shear strain and Ge concentration oscillations
• Measurement of tunnel coupling in a Si double quantum dot based on charge sensing
• Valley splitting depending on the size and location of a silicon quantum dot
• Flopping-mode electron dipole spin resonance in the strong-driving regime
• Charge-noise resilience of two-electron quantum dots in Si/SiGe heterostructures