A5002694419- Quantum and electron transport phenomena
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor Quantum Structures and Devices
- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum optics and atomic interactions
- Magnetic properties of thin films
- Nanowire Synthesis and Applications
- Graphene research and applications
- Molecular Junctions and Nanostructures
- Silicon and Solar Cell Technologies
- Diamond and Carbon-based Materials Research
- Atomic and Subatomic Physics Research
- Force Microscopy Techniques and Applications
- Silicon Nanostructures and Photoluminescence
- Semiconductor Lasers and Optical Devices
- 2D Materials and Applications
- Quantum-Dot Cellular Automata
- Neural Networks and Reservoir Computing
- Integrated Circuits and Semiconductor Failure Analysis
- Electron and X-Ray Spectroscopy Techniques
- Topological Materials and Phenomena
- GaN-based semiconductor devices and materials
- Semiconductor materials and interfaces
Quantum (Australia)
2022-2024
UNSW Sydney
2022-2024
Centre for Quantum Computation and Communication Technology
2022-2024
Purdue University West Lafayette
2014-2018
Monash University
2017
Single electron spins bound to multi-phosphorus nuclear spin registers in silicon have demonstrated fast (0.8 ns) two-qubit
Scaling up to large arrays of donor-based spin qubits for quantum computation will require the ability perform high-fidelity readout multiple individual qubits. Recent experiments have shown that limiting factor many is lifetime electron spin. We demonstrate longest reported lifetimes (up 30 s) any qubit in a nanoelectronic device. By atomic-level engineering wave function within phosphorus atom dots, we can minimize relaxation agreement with recent theoretical predictions. These allow us...
Spins confined to atomically thin semiconductors are being actively explored as quantum information carriers. In transition metal dichalcogenides (TMDCs), the hexagonal crystal lattice gives rise an additional valley degree of freedom with spin-valley locking and potentially enhanced spin life coherence times. However, realizing well-separated single-particle levels achieving transparent electrical contact address them has remained challenging. Here, we report well-defined states in a...
Abstract Spin‐orbit interactions arise whenever the bulk inversion symmetry and/or structural of a crystal is broken providing bridge between qubit's spin and orbital degree freedom. While strong can facilitate fast qubit operations by all‐electrical control, they also provide mechanism to couple charge noise thereby limiting lifetimes. Previously believed be negligible in silicon, recent silicon nano‐electronic devices have shown larger than spin‐orbit coupling strengths from Dresselhaus...
An atomistic method of calculating the spin-lattice relaxation times (T₁) is presented for donors in silicon nanostructures comprising millions atoms. The takes into account full band structure including spin-orbit interaction. electron-phonon Hamiltonian, and hence, deformation potential, directly evaluated from strain-dependent tight-binding Hamiltonian. technique applied to single donor clusters silicon, explains variation T₁ with number electrons, as well locations. Without any...
Abstract Spin–orbit coupling (SOC) is fundamental to a wide range of phenomena in condensed matter, spanning from renormalisation the free-electron g -factor, formation topological insulators, and Majorana Fermions. SOC has also profound implications spin-based quantum information, where it known limit spin lifetimes ( T 1 ) inversion asymmetric semiconductors such as GaAs. However, for electrons silicon—and particular those bound phosphorus donor qubits—SOC usually regarded weak, allowing...
Abstract Controlling electron tunneling is of fundamental importance in the design and operation semiconductor nanostructures such as field effect transistors (FETs) quantum computing device architectures. The exponential sensitivity with distance requires precise fabrication techniques to engineer desired dimensions achieve appropriate resistances/tunnel rates. This particularly important for high fidelity spin readout qubit exchange Here, it shown by combining precision accurate atomistic...
The energy spectrum of spin-orbit coupled states individual sub-surface boron acceptor dopants in silicon have been investigated using scanning tunneling spectroscopy (STS) at cryogenic temperatures. spatially resolved tunnel spectra show two resonances which we ascribe to the heavy- and light-hole Kramers doublets. This type broken degeneracy has recently argued be advantageous for lifetime acceptor-based qubits [Phys. Rev. B 88 064308 (2013)]. depth dependent splitting between doublets is...
Electrically addressing spin systems is predicted to be a key component in developing scalable semiconductor-based quantum-processing architectures, enable fast spin-qubit manipulation and long-distance entanglement via microwave photons. However, single spins have no electric dipole, therefore spin-orbit mechanism must integrated the qubit design. Here, we propose couple photons atomically precise donor devices silicon using hyperfine interaction intrinsic an electrically induced coupling....
Donor electron spin qubits hosted within nanoscale devices have demonstrated seconds-long relaxation times at magnetic fields suitable for the operation of in silicon $B=1.5\phantom{\rule{0.16em}{0ex}}\mathrm{T}$. The rates these been shown milliKelvin temperatures to be mediated by spin-orbit coupling with a ${B}^{5}$ dependency on field $B>3\phantom{\rule{0.16em}{0ex}}\mathrm{T}$ transition ${B}^{3}$ below ($B\ensuremath{\le}3\phantom{\rule{0.16em}{0ex}}\mathrm{T}$). This deviation has...
Phosphorus donor nuclear spins in silicon couple weakly to the environment, making them promising candidates for high-fidelity qubits. The state of a spin qubit can be manipulated and read out using its hyperfine interaction with electron confined by potential. Here we use master-equation-based approach investigate how backaction from this electron-mediated measurement affects lifetimes single multidonor We analyze process as function electric magnetic fields strength. Apart flips, identify...
While traditionally considered a deleterious effect in quantum dot spin qubits, the spin-orbit interaction is recently being revisited as it allows for rapid coherent control by on-chip AC electric fields. For electrons bulk silicon, coupling (SOC) intrinsically weak, however, can be enhanced at surfaces and interfaces, or through atomic placement. Here showed that strength of locally more than two orders magnitude manybody wave functions multi-donor dots compared to single donor, reaching...
The two-electron states and exchange couplings are investigated for a phosphorous donor pair in silicon using an atomistic full configuration interaction method separations spanning from 0.4 to 15 nm. Three distinct separation regimes appear our large basis calculations, which the validity of simplified methods such as Heitler-London Hartree-Fock type approaches can be assessed. For bulk donors, coupling saturates below 5 nm due excited bonding orbital contributions wave functions. Ionic...
Singlet-triplet qubits typically require large magnetic field gradients on the order of militeslas to achieve high-fidelity electrically-controlled qubit operations. However, such in quantum dot systems also increase charge noise and provide a relaxation pathway from triplet singlet state, making readout challenging. Recently, shelving latched have been employed gate-defined dots donor-dot fidelities 80% 99.86%, respectively. In this paper, we theoretically examine singlet-triplet techniques...
Abstract Obtaining an accurate first-principle description of the electronic properties dopant qubits is critical for engineering and optimizing high-performance quantum computing. However, density functional theory (DFT) has had limited success in providing a full quantitative these dopants due to their large wavefunction extent. Here, we build on recent advances DFT evaluate phosphorus silicon lattice comprised 4096 atoms with hybrid functionals pseudopotential all-electron mixed approach....
Self-assembled quantum dots are highly strained heterostructures, and a rigorous atomistic strain model is needed to predict the behavior of these devices. An anharmonic reported by Lazarenkova, et al. [1] modifies well-known harmonic Keating [2] include effect anharmonicity in lattice potential. The Lazarenkova parameters were originally optimized deliver correct Grüneisen parameters, however this optimization does not provide values that compare well obtained experiments on both wells...
A detailed theoretical study of the optical absorption in doped self-assembled quantum dots is presented. rigorous atomistic strain model as well a sophisticated 20-band tight-binding are used to ensure accurate prediction single particle states these devices. We also show that for dots, many-particle configuration interaction critical accurately capture transitions system. The models presented this work reproduce experimental results both undoped and dot systems. effects alloy mole fraction...
While traditionally considered a deleterious effect in quantum dot spin qubits, the spin-orbit interaction is recently being revisited as it allows for rapid coherent control by on-chip AC electric fields. For electrons bulk silicon, SOC intrinsically weak, however, can be enhanced at surfaces and interfaces, or through atomic placement. Here we show that strength of coupling locally more than two orders magnitude manybody wave functions multi-donor dots compared to single donor, reaching...
Correlated noise across multi-qubit architectures is known to be highly detrimental the operation of error correcting codes and long-term feasibility quantum processors. The recent discovery spatially dependent correlated in superconducting qubits arising from impact cosmic radiation high-energy particles giving rise quasiparticle poisoning within substrate has led intense investigations mitigation strategies address this. In contrast semiconductor spin as a function distance not been...
Universal quantum computing requires fast single- and two-qubit gates with individual qubit addressability to minimize decoherence errors during processor operation. Electron spin qubits using phosphorus donor atoms in silicon have demonstrated long coherence times high fidelities, providing an attractive platform for scalable computing. While has been by controlling the hyperfine interaction between electron nuclear wave function a global magnetic field, small Stark coefficient of 0.34...
A detailed theoretical study of the optical absorption in self-assembled quantum dots is presented this paper. rigorous atomistic strain model as well a sophisticated electronic band structure are used to ensure accurate prediction transitions these devices . The optimized models paper able reproduce experimental results with an error less than 1$\%$. effects incident light polarization, alloy mole fraction, dot dimensions, and doping have been investigated. in-plane polarized more...
two references was also added to the manuscript, at start of fifth paragraph introduction