Theory of valley-orbit coupling in a Si/SiGe quantum dot

Abstract

Electron states are studied for quantum dots in a strained Si quantum well, taking into account both valley and orbital physics. Realistic geometries are considered, including circular and elliptical dot shapes, parallel and perpendicular magnetic fields, and (most importantly for valley coupling) the small local tilt of the quantum well interface away from the crystallographic axes. In absence of a tilt, valley splitting occurs only between pairs of states with the same orbital quantum numbers. However, tilting is ubiquitous in conventional silicon heterostructures, leading to valley-orbit coupling. In this context, "valley splitting" is no longer a well defined concept, and the quantity of merit for qubit applications becomes the ground state gap. For typical dots used as qubits, a rich energy spectrum emerges, as a function of magnetic field, tilt angle, and orbital quantum number. Numerical and analytical solutions are obtained for the ground state gap and for the mixing fraction between the ground and excited states. This mixing can lead to valley scattering, decoherence, and leakage for Si spin qubits.

18 pages, including 4 figures

References in corpus (19)

• Single-shot read-out of an individual electron spin in a quantum dot
• Andreev reflection and Klein tunneling in graphene
• Strong suppression of weak (anti)localization in graphene
• Intervalley scattering, long-range disorder, and effective time reversal symmetry breaking in graphene
• Controllable valley splitting in silicon quantum devices
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Valley Polarization in Si(100) at Zero Magnetic Field
• Pauli-Spin-Blockade Transport through a Silicon Double Quantum Dot
• Spin and valley-orbit splittings in SiGe/Si heterostructures
• Charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• Electric field effect on electron spin splitting in SiGe/Si quantum wells
• Single-electron quantum dot in Si/SiGe with integrated charge-sensing
• The Two-flux Composite Fermion Series of Fractional Quantum Hall States in Strained Si
• Enhancement mode double top gated MOS nanostructures with tunable lateral geometry
• Coulomb blockade and Kondo effect in a few-electron silicon/silicon-germanium quantum dot
• Charge sensing in enhancement mode double-top-gated metal-oxide-semiconductor quantum dots
• Valley splitting in Si quantum dots embedded in SiGe
• Ion implanted Si:P double-dot with gate tuneable interdot coupling

Cited by in corpus (87)

• Silicon Quantum Electronics
• Semiconductor Spin Qubits
• Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot
• Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
• Tunable spin-selective loading of a silicon spin qubit
• Electrically driven electron spin resonance mediated by spin-valley-orbit coupling in a silicon quantum dot
• Interface roughness, valley-orbit coupling and valley manipulation in quantum dots
• Valley-based noise-resistant quantum computation using Si quantum dots
• Spin-orbit coupling and operation of multi-valley spin qubits
• Charge Relaxation in a Single Electron Si/SiGe Double Quantum Dot
• Relaxation of excited spin, orbital, and valley qubit states in single electron silicon quantum dots
• Intervalley coupling by quantum dot confinement potentials in monolayer transition metal dichalcogenides
• Atomic fluctuations lifting the energy degeneracy in Si/SiGe quantum dots
• Quantum dot spin qubits in Silicon: Multivalley physics
• Intervalley coupling for interface-bound electrons in silicon: An effective mass study
• Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO${}_2$
• Spin relaxation in a Si quantum dot due to spin-valley mixing
• Tunable singlet-triplet splitting in a few-electron Si/SiGe quantum dot
• Resonant tunnelling features in the transport spectroscopy of quantum dots
• Genetic Design of Enhanced Valley Splitting towards a Spin Qubit in Silicon
• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Dispersive readout of valley splittings in cavity-coupled silicon quantum dots
• Electron g-factor of valley states in realistic silicon quantum dots
• Disorder-induced valley-orbit hybrid states in Si quantum dots
• Spin filling of valley-orbit states in a silicon quantum dot
• Spin shuttling in a silicon double quantum dot
• Orbital and valley state spectra of a few-electron silicon quantum dot
• Direct bandgap silicon quantum dots achieved via electronegative capping
• Strong electron-electron interactions in Si/SiGe quantum dots
• Giant anisotropy of spin relaxation and spin-valley mixing in a silicon quantum dot
• Spin-valley blockade in carbon nanotube double quantum dots
• 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
• Theory of Single Electron Spin Relaxation in Si/SiGe Lateral Coupled Quantum Dots
• Effective Hamiltonian for the hybrid double quantum dot qubit
• Two-electron dephasing in single Si and GaAs quantum dots
• Engineered valley-orbit splittings in quantum confined nanostructures in silicon
• How valley-orbit states in silicon quantum dots probe quantum well interfaces
• A quadrupolar exchange-only spin qubit
• Dressed photon-orbital states in a quantum dot: Inter-valley spin resonance
• Mapping of valley-splitting by conveyor-mode spin-coherent electron shuttling
• Effects of Interface Steps on the Valley Orbit coupling in a Si/SiGe quantum dot
• Spin-Blockade Spectroscopy of Si/SiGe Quantum Dots
• Two-body Wigner molecularization in asymmetric quantum dot spin qubits
• Lifetime enhanced transport in silicon due to spin and valley blockade
• 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
• A many-electron tight binding method for the analysis of quantum dot systems
• Theory of Spin Relaxation in Two-Electron Lateral Coupled Si/SiGe Quantum Dots
• Signatures of atomic-scale structure in the energy dispersion and coherence of a Si quantum-dot qubit
• Impact of valley phase and splitting on readout of silicon spin qubits
• Transporting a single-spin qubit through a double quantum dot
• Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling
• Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• Multi-valley envelope function equations and effective potentials for P impurity in silicon
• SiGe/Si quantum dot electron spin decoherence dependence on ${}^{73}$Ge
• Valley Phase and Voltage Control of Coherent Manipulation in Si Quantum Dots
• Electrical operation of hole spin qubits in planar MOS silicon quantum dots
• Electric dipole spin resonance in systems with a valley dependent g-factor
• Magnetic gradient free two axis control of a valley spin qubit in SiGe
• Coulomb interaction and valley-orbit coupling in Si quantum dots
• Valley splitting depending on the size and location of a silicon quantum dot
• Linear and planar molecules formed by coupled P donors in silicon
• Valleytronic full configuration-interaction approach: An application to the excitation spectra of Si double-dot qubits
• Calculation of tunnel-couplings in open gate-defined disordered quantum dot systems
• Valley splitting in a Si/SiGe quantum point contact
• Phonon-induced relaxation and decoherence times of the hybrid qubit in silicon quantum dots
• Heterogeneous nucleation of pits via step pinning during Si(100) homoepitaxy
• Theory of Silicon Spin Qubit Relaxation in a Synthetic Spin-Orbit Field
• Charge-noise resilience of two-electron quantum dots in Si/SiGe heterostructures
• Valley and spin splittings in PbSe nanowires
• Optimisation of electrically-driven multi-donor quantum dot qubits
• Orbital hyperfine interaction and qubit dephasing in carbon nanotube quantum dots
• Valley Splitting Correlations Across a Silicon Quantum Well Containing Germanium
• Scalable Parity Architecture With a Shuttling-Based Spin Qubit Processor
• Leakage and dephasing in ${}^{28}$Si-based exchange-only spin qubits
• Few-electrode design for silicon MOS quantum dots
• Sign-switching of superexchange mediated by few electrons under non-uniform magnetic field
• Signatures of Valley Kondo Effect in Si/SiGe Quantum Dots
• Proposal for a cavity-induced measurement of the exchange coupling in quantum dots
• Assessing quantum dot SWAP gate fidelity using tensor network methods
• Impact of the valley orbit coupling on exchange gate for spin qubits in silicon quantum dots
• Proposed Five-Electron Charge Quadrupole Qubit
• Non-adiabatic quantum control of valley states in silicon
• Phonon-induced frequency shift in semiconductor spin qubits