Effects of Interface Steps on the Valley Orbit coupling in a Si/SiGe quantum dot

Abstract

Valley-orbit coupling is a key parameter for a silicon quantum dot in determining its suitability for applications in quantum information processing. In this paper we study the effect of interface steps on the magnitude and phase of valley-orbit coupling for an electron in a silicon quantum dot. Within the effective mass approximation, we find that the location of a step on the interface is important in determining both the magnitude and the phase of the valley-orbit coupling in a Si/SiGe quantum dot. Specifically, our numerical results show that the magnitude of valley orbit coupling can be suppressed up to 75\% by a step of one atomic monolayer, and its phase can change by almost $\pi$. When two steps are present, the minimum value of the valley-orbit coupling can even approach zero. We also clarify the effects of an applied external magnetic field and the higher orbital states on the valley-orbit coupling. Overall, our results illustrate how interface roughness affect the valley-orbit coupling in silicon, and how spin qubits in silicon may be affected.

arXiv comment14 pages, 15 figures

References in corpus (54)

• Coupled quantum dots as quantum gates
• Silicon Quantum Electronics
• An addressable quantum dot qubit with fault-tolerant control fidelity
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• A single-atom electron spin qubit in silicon
• Single-shot readout of an electron spin in silicon
• Storing quantum information for 30 seconds in a nanoelectronic device
• Quantum CNOT Gate for Spins in Silicon
• Solid state quantum memory using the 31P nuclear spin
• Manipulation of a single charge in a double quantum dot
• Silicon CMOS architecture for a spin-based quantum computer
• Hilbert space structure of a solid state quantum computer: two-electron states of a double quantum dot artificial molecule
• Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
• Strong Coupling of a Single Electron in Silicon to a Microwave Photon
• Shuttling a single charge across a one-dimensional array of silicon quantum dots
• Controllable valley splitting in silicon quantum devices
• A fault-tolerant addressable spin qubit in a natural silicon quantum dot
• A fast "hybrid" silicon double quantum dot qubit
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
• Coherent shuttle of electron-spin states
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• High-fidelity quantum gates in Si/SiGe double quantum dots
• Physical mechanisms of interface-mediated intervalley coupling in Si
• Interface roughness, valley-orbit coupling and valley manipulation in quantum dots
• Spin and valley-orbit splittings in SiGe/Si heterostructures
• Valley-based noise-resistant quantum computation using Si quantum dots
• High fidelity resonant gating of a silicon based quantum dot hybrid qubit
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• High Resolution Valley Spectroscopy of Si Quantum Dots
• Quantum dot spin qubits in Silicon: Multivalley physics
• Intervalley coupling for interface-bound electrons in silicon: An effective mass study
• Spin relaxation in a Si quantum dot due to spin-valley mixing
• Valley dependent anisotropic spin splitting in silicon quantum dots
• Dispersive readout of valley splittings in cavity-coupled silicon quantum dots
• Interface induced spin-orbit interaction in silicon quantum dots and prospects for scalability
• Valley splitting of single-electron Si MOS quantum dots
• Disorder-induced valley-orbit hybrid states in Si quantum dots
• Computer-automated tuning procedures for semiconductor quantum dot arrays
• Shallow donor wavefunctions and donor-pair exchange in silicon: Ab initio theory and floating-phase Heitler-London approach
• An electrically driven spin qubit based on valley mixing
• Control of valley dynamics in silicon quantum dots in the presence of an interface step
• All-electrical manipulation of silicon spin qubits with tunable spin-valley mixing
• Second Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot
• Valley splitting in Si quantum dots embedded in SiGe
• A linear triple quantum dot system in isolated configuration
• Nanosecond-timescale spin transfer using individual electrons in a quadruple-quantum-dot device
• Impact of valley phase and splitting on readout of silicon spin qubits
• Signatures of atomic-scale structure in the energy dispersion and coherence of a Si quantum-dot qubit
• Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling
• Valley Phase and Voltage Control of Coherent Manipulation in Si Quantum Dots
• Coulomb interaction and valley-orbit coupling in Si quantum dots
• Coherent electron transport in silicon quantum dots
• Resonant tunneling spectroscopy of valley eigenstates on a hybrid double quantum dot

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• Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO${}_2$
• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Giant anisotropy of spin relaxation and spin-valley mixing in a silicon quantum dot
• Strong electron-electron interactions in Si/SiGe quantum dots
• Variability of electron and hole spin qubits due to interface roughness and charge traps
• Electromagnetic control of valley splitting in ideal and disordered Si quantum dots
• Two-body Wigner molecularization in asymmetric quantum dot spin qubits
• Probing the Spatial Variation of the Inter-Valley Tunnel Coupling in a Silicon Triple Quantum Dot
• Utilizing multimodal microscopy to reconstruct Si/SiGe interfacial atomic disorder and infer its impacts on qubit variability
• Switching between relaxation hotspots and coldspots in disordered spin qubits
• Interface and electromagnetic effects in the valley splitting of Si quantum dots
• Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures
• Spin-Valley Qubit Dynamics In Exchange Coupled Silicon Quantum Dots
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• 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
• Theory of valley-resolved spectroscopy of a Si triple quantum dot coupled to a microwave resonator
• Theory of Silicon Spin Qubit Relaxation in a Synthetic Spin-Orbit Field
• Suppressing Si Valley Excitation and Valley-Induced Spin Dephasing for Long-Distance Shuttling
• Omnidirectional shuttling to avoid valley excitations in Si/SiGe quantum wells
• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots
• Impact of the valley orbit coupling on exchange gate for spin qubits in silicon quantum dots
• Non-adiabatic quantum control of valley states in silicon