Calculation of tunnel-couplings in open gate-defined disordered quantum dot systems

Abstract

Quantum computation based on semiconductor electron-spin qubits requires high control of tunnel-couplings, both across quantum dots and between the quantum dot and the reservoir. The tunnel-coupling to the reservoir sets the qubit detection and initialization bandwidth for energy-resolved spin-to-charge conversion and is essential to tune single-electron transistors commonly used as charge detectors. Potential disorder and the increasing complexity of the two-dimensional gate-defined quantum computing devices sets high demands on the gate design and the voltage tuning of the tunnel barriers. We present a Green's formalism approach for the calculation of tunnel-couplings between a quantum dot and a reservoir. Our method takes into account in full detail the two-dimensional electrostatic potential of the quantum dot, the tunnel barrier and reservoir. A Markov approximation is only employed far away from the tunnel barrier region where the density of states is sufficiently large. We calculate the tunnel-coupling including potential disorder effects, which become increasingly important for large-scale silicon-based spin-qubit devices. Studying the tunnel-couplings of a single-electron transistor in Si/SiGe as a showcase, we find that charged defects are the dominant source of disorder leading to variations in the tunnel-coupling of four orders of magnitude.

arXiv comment10 pages, 4 figures

References in corpus (30)

• Spins in few-electron quantum dots
• Single-shot read-out of an individual electron spin in a quantum dot
• Silicon Quantum Electronics
• An addressable quantum dot qubit with fault-tolerant control fidelity
• A Two Qubit Logic Gate in Silicon
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• A programmable two-qubit quantum processor in silicon
• Interfacing spin qubits in quantum dots and donors - hot, dense and coherent
• A CMOS silicon spin qubit
• Demonstration of Entanglement of Electrostatically Coupled Singlet-Triplet Qubits
• Silicon CMOS architecture for a spin-based quantum computer
• Rapid Single-Shot Measurement of a Singlet-Triplet Qubit
• Scalable gate architecture for densely packed semiconductor spin qubits
• Self-Consistent Measurement and State Tomography of an Exchange-Only Spin Qubit
• A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• Tunnel splittings for one dimensional potential wells revisited
• Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins
• The double well potential in quantum mechanics: a simple, numerically exact formulation
• Pauli spin blockade in undoped Si/SiGe two-electron double quantum dots
• Coherent long-distance displacement of individual electron spins
• Computer-automated tuning of semiconductor double quantum dots into the single-electron regime
• Investigation of Mobility Limiting Mechanisms in Undoped Si/SiGe Heterostructures
• Full control of quadruple quantum dot circuit charge states in the single electron regime
• Quadrupolar and anisotropy effects on dephasing in two-electron spin qubits in GaAs
• Highly tuneable hole quantum dots in Ge-Si core-shell nanowires
• Efficient self-consistent quantum transport simulator for quantum devices
• Reconfigurable quadruple quantum dots in a silicon nanowire transistor
• Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells
• Voltage controlled exchange energies of a two electron silicon double quantum dot with and without charge defects in the dielectric

Cited by in corpus (6)

• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Si/SiGe QuBus for single electron information-processing devices with memory and micron-scale connectivity function
• Simulation of 1/f charge noise affecting a quantum dot in a Si/SiGe structure
• Bridging the reality gap in quantum devices with physics-aware machine learning
• Tailoring potentials by simulation-aided design of gate layouts for spin qubit applications
• Numerical simulation of coherent spin-shuttling in a QuBus with charged defects