Spin-Valley Qubit Dynamics In Exchange Coupled Silicon Quantum Dots

Abstract

The presence of valley states is a significant obstacle to realizing quantum information technologies in Silicon quantum dots, as leakage into alternate valley states can introduce errors into the computation. We use a perturbative analytical approach to study the dynamics of exchange-coupled quantum dots with valley degrees of freedom. We show that if the valley splitting is large and electrons are not properly initialized to valley eigenstates, then time evolution of the system will lead to spin-valley entanglement. Spin-valley entanglement will also occur if the valley splitting is small and electrons are not initialized to the same valley state. Additionally, we show that for small valley splitting, spin-valley entanglement does not affect measurement probabilities of two-qubit systems; however, systems with more qubits will be affected. This means that two-qubit gate fidelities measured in two-qubit systems may miss the effects of valley degrees of freedom. Our work shows how the existence of valleys may adversely affect multiqubit fidelities even when the system temperature is very low.

10 pages, 6 figures

References in corpus (7)

• Scalable gate architecture for densely packed semiconductor spin qubits
• Bound states and magnetic field-induced valley splitting in gate-tunable graphene quantum dots
• Electron spin decoherence in isotope-enriched silicon
• Physical mechanisms of interface-mediated intervalley coupling in Si
• Site-selective quantum control in an isotopically enriched 28Si/SiGe quadruple quantum dot
• Hubbard model description of silicon spin qubits: charge stability diagram and tunnel coupling in Si double quantum dots
• Orbital and valley state spectra of a few-electron silicon quantum dot

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• Leveraging Off-the-Shelf Silicon Chips for Quantum Computing
• Proposal for a cavity-induced measurement of the exchange coupling in quantum dots
• Advancements in Entangled Photon Pairs in 2D Van der Waals Materials for On-chip Quantum Applications
• Negative exchange interaction in Si quantum dot arrays via valley-phase induced ${\mathbb{Z}}_2$ gauge field
• Effects of valley splitting on resonant-tunneling readout of spin qubits