Controllable valley splitting in silicon quantum devices

Abstract

Silicon has many attractive properties for quantum computing, and the quantum dot architecture is appealing because of its controllability and scalability. However, the multiple valleys in the silicon conduction band are potentially a serious source of decoherence for spin-based quantum dot qubits. Only when these valleys are split by a large energy does one obtain well-defined and long-lived spin states appropriate for quantum computing. Here we show that the small valley splittings observed in previous experiments on Si/SiGe heterostructures result from atomic steps at the quantum well interface. Lateral confinement in a quantum point contact limits the electron wavefunctions to several steps, and enhances the valley splitting substantially, up to 1.5 meV. The combination of electronic and magnetic confinement produces a valley splitting larger than the spin splitting, which is controllable over a wide range. These results improve the outlook for realizing spin qubits with long coherence times in silicon-based devices.

Published version, including supplementary materials

References in corpus (8)

• Single-shot read-out of an individual electron spin in a quantum dot
• Elastically Relaxed Free-standing Strained-Si Nanomembranes
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Recipes for spin-based quantum computing
• Valley Polarization in Si(100) at Zero Magnetic Field
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• The Two-flux Composite Fermion Series of Fractional Quantum Hall States in Strained Si
• Conductance quantization in etched Si/SiGe quantum point contacts

Cited by in corpus (126)

• Silicon Quantum Electronics
• Single-shot readout of an electron spin in silicon
• Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
• A fast "hybrid" silicon double quantum dot qubit
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Tunable spin-selective loading of a silicon spin qubit
• Pauli-Spin-Blockade Transport through a Silicon Double Quantum Dot
• Measurement of the Spin Relaxation Time of Single Electrons in a Silicon MOS-Based Quantum Dot
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• Physical mechanisms of interface-mediated intervalley coupling in Si
• 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
• Electron spin resonance and spin-valley physics in a silicon double quantum dot
• Charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot
• Fast coherent manipulation of three-electron states in a double quantum dot
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Spatially Resolving Valley Quantum Interference of a Donor in Silicon
• Universal Quantum Computing with Spin and Valley
• Exchange coupling in silicon quantum dots: Theoretical considerations for quantum computation
• Hole Spin Coherence in a Ge/Si Heterostructure Nanowire
• Charge Relaxation in a Single Electron Si/SiGe Double Quantum Dot
• Valley Contrasting Magnetoluminescence in Monolayer MoS${}_2$ Quantum Hall Systems
• Intervalley coupling by quantum dot confinement potentials in monolayer transition metal dichalcogenides
• Valley Polarization in Size-Tunable Monolayer Semiconductor Quantum Dots
• Strong coupling of spin qubits to a transmission line resonator
• Quantum dot spin qubits in Silicon: Multivalley physics
• Intervalley coupling for interface-bound electrons in silicon: An effective mass study
• Room-Temperature Charge Stability Modulated by Quantum Effects in a Nanoscale Silicon Island
• 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
• Electrotunable artificial molecules based on van der Waals heterostructures
• Charge Number Dependence of the Dephasing Rates of a Graphene Double Quantum Dot in a Circuit QED Architecture
• Hubbard model description of silicon spin qubits: charge stability diagram and tunnel coupling in Si double quantum dots
• Electron g-factor of valley states in realistic silicon quantum dots
• Investigation of Mobility Limiting Mechanisms in Undoped Si/SiGe Heterostructures
• Valley splitting of single-electron Si MOS quantum dots
• Detection of a large valley-orbit splitting in silicon with two-donor spectroscopy
• Disorder-induced valley-orbit hybrid states in Si quantum dots
• A logical qubit in a linear array of semiconductor quantum dots
• Spin filling of valley-orbit states in a silicon quantum dot
• Strong electron-electron interactions in Si/SiGe quantum dots
• Valley subband splitting in bilayer graphene quantum point contact
• Coherent electron transport by adiabatic passage in an imperfect donor chain
• Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots
• Hybrid spin and valley quantum computing with singlet-triplet qubits
• 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
• Quantum theory of the charge stability diagram of semiconductor double quantum dot systems
• Engineered valley-orbit splittings in quantum confined nanostructures in silicon
• The critical role of substrate disorder in valley splitting in Si quantum wells
• A quadrupolar exchange-only spin qubit
• Valley Degenerate 2D Electrons in the Lowest Landau Level
• Dressed photon-orbital states in a quantum dot: Inter-valley spin resonance
• Electromagnetic control of valley splitting in ideal and disordered Si quantum dots
• Hybrid superconductor-semiconductor systems for quantum technology
• Effects of Interface Steps on the Valley Orbit coupling in a Si/SiGe quantum dot
• Atomistic simulations of adiabatic coherent electron transport in triple donor systems
• Single and Double Hole Quantum Dots in Strained Ge/SiGe Quantum Wells
• 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
• Valley splitting in Si quantum dots embedded in SiGe
• Pauli spin blockade and lifetime-enhanced transport in a Si/SiGe double quantum dot
• Utilizing multimodal microscopy to reconstruct Si/SiGe interfacial atomic disorder and infer its impacts on qubit variability
• Multivalley two-dimensional electron system in an AlAs quantum well with mobility exceeding $2\times 10^6$ cm${}^2$V${}^{-1}$s${}^{-1}$
• Extended interface states enhance valley splitting in Si/SiO2
• Excitonic Aharonov-Bohm Effect in Isotopically Pure 70Ge/Si Type-II Quantum Dots
• Enhanced Valley Splitting in Si Layers with Oscillatory Ge Concentration
• Spin decoherence in a two-qubit CPHASE gate: the critical role of tunneling noise
• Valley Kondo Effect in Silicon Quantum Dots
• Theory of Spin Relaxation in Two-Electron Lateral Coupled Si/SiGe Quantum Dots
• Spin-dependent scattering in a silicon transistor
• Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells
• Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling
• Long-Range Interaction between Charge and Spin Qubits in Quantum Dots
• Valley-Polarized quantum Hall phase in a strain-controlled Dirac system
• Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures
• Pauli spin blockade in CMOS double quantum dot devices
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• Valley Phase and Voltage Control of Coherent Manipulation in Si Quantum Dots
• Phonon-assisted relaxation and decoherence of singlet-triplet qubits in Si/SiGe quantum dots
• Quantum Hall Resistance Overshoot in 2-Dimensional Electron Gases - Theory and Experiment
• Magnetic gradient free two axis control of a valley spin qubit in SiGe
• Electrical operation of hole spin qubits in planar MOS silicon quantum dots
• Electric dipole spin resonance in systems with a valley dependent g-factor
• Mapping donor electron wave function deformations at sub-Bohr orbit resolution
• Effect of quantum Hall edge strips on valley splitting in silicon quantum wells
• Valley filtering and spatial maps of coupling between silicon donors and quantum dots
• Origin of giant valley splitting in silicon quantum wells induced by superlattice barriers
• Coulomb interaction and valley-orbit coupling in Si quantum dots
• Electron spin blockade and singlet-triplet transition in a silicon single electron transistor
• Well-width dependence of valley splitting in Si/SiGe quantum wells
• Multiscale theory of valley splitting
• A strain-engineered graphene qubit in a nanobubble
• Impact of the valley degree of freedom on the control of donor electrons near a Si/SiO_2 interface
• Valley degeneracy in biaxially strained aluminum arsenide quantum wells
• Characterization of a gate-defined double quantum dot in a Si/SiGe nanomembrane
• Splitting Valleys in Si/SiO${}_2$: Identification and Control of Interface States
• Direct measurement of electron intervalley relaxation in a Si/SiGe quantum dot
• Interaction between interface and massive states in multivalley topological heterostructures
• Valley splitting in a Si/SiGe quantum point contact
• Heterogeneous nucleation of pits via step pinning during Si(100) homoepitaxy
• Fragility of the Dirac Cone Splitting in Topological Crystalline Insulator Heterostructures
• Phonon-induced decoherence of a charge quadrupole qubit
• Resonant tunneling spectroscopy of valley eigenstates on a hybrid double quantum dot
• Charge noise suppression in capacitively coupled singlet-triplet spin qubits under magnetic field
• Spin-Valley Kondo Effect in Multi-electron Silicon Quantum Dots
• Dynamical second-order noise sweetspots in resonantly driven spin qubits
• Proposals of nuclear spin quantum memory in group IV elemental and II-VI semiconductors
• Energy spectra of three electrons in SiGe/Si/SiGe laterally coupled triple quantum dots
• Spin relaxation of a donor electron coupled to interface states
• Prediction of the spin triplet two-electron quantum dots in Si: towards controlled quantum simulations of magnetic systems
• Intervalley splittings of Si quantum wells
• Signatures of Valley Kondo Effect in Si/SiGe Quantum Dots
• Valley blockade in a silicon double quantum dot
• Fast spin-valley-based quantum gates in Si with micromagnets
• Density dependence of the excitation gaps in an undoped Si/SiGe double-quantum-well heterostructure
• Valley polarization dynamics of photoinjected carriers at the band edge in room-temperature silicon studied by terahertz polarimetry
• New symmetric families of silicon quantum dots and their conglomerates as a tunable source of photoluminescence in nanodevices
• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots
• Efficient unitary method for simulation of driven quantum dot systems
• Effects of valley splitting on resonant-tunneling readout of spin qubits
• Magnetotransport in non-planar SiGe/Si nanomembranes