A5084314813- Quantum and electron transport phenomena
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and devices
- Semiconductor Quantum Structures and Devices
- Quantum Computing Algorithms and Architecture
- Integrated Circuits and Semiconductor Failure Analysis
- Quantum Information and Cryptography
- Electron and X-Ray Spectroscopy Techniques
- Magnetic properties of thin films
- Quantum-Dot Cellular Automata
- Surface and Thin Film Phenomena
- Advanced Electron Microscopy Techniques and Applications
- Semiconductor materials and interfaces
- Silicon Nanostructures and Photoluminescence
- Ion-surface interactions and analysis
- Ferroelectric and Negative Capacitance Devices
- Advanced Materials Characterization Techniques
- Photonic and Optical Devices
- Plant Pathogens and Fungal Diseases
- Photocathodes and Microchannel Plates
- Physics of Superconductivity and Magnetism
- Molecular Junctions and Nanostructures
- Nanowire Synthesis and Applications
- Advancements in Photolithography Techniques
- Seedling growth and survival studies
Jülich Aachen Research Alliance
2017-2025
Forschungszentrum Jülich
2017-2025
RWTH Aachen University
2015-2025
Australian National University
2023
Delft University of Technology
2011-2014
Semiconductor spins are one of the few qubit realizations that remain a serious candidate for implementation large-scale quantum circuits. Excellent scalability is often argued spin qubits defined by lithography and controlled via electrical signals, based on success conventional semiconductor integrated However, wiring interconnect requirements circuits completely different from those classical circuits, as individual DC, pulsed in some cases microwave control signals need to be routed...
Small spin-qubit registers defined by single electrons confined in Si/SiGe quantum dots operate successfully and connecting these would permit scalable computation. Shuttling the qubit carrying between is a natural choice for high-fidelity coherent links provided overhead of control signals stays moderate. Our proof-of-principle demonstrates shuttling electron propagating wave-potential an electrostatically 420 nm long quantum-channel. This conveyor-mode approach requires independent from...
The connectivity within single carrier information-processing devices requires transport and storage of charge quanta. Single electrons have been adiabatically transported while confined to a moving quantum dot in short, all-electrical Si/SiGe shuttle device, called bus (QuBus). Here we show QuBus spanning length 10 μm operated by only six simply-tunable voltage pulses. We introduce characterization method, shuttle-tomography, benchmark the potential imperfections local shuttle-fidelity...
Independent readout of two single-spin qubits in quantum dots is achieved an all-electrical setup.
Valley splitting is a key figure of silicon-based spin qubits. Quantum dots in Si/SiGe heterostructures reportedly suffer from relatively low valley splitting, limiting the operation temperature and scalability such qubit devices. Here, we demonstrate robust large exceeding 200 $\mu$eV gate-defined single quantum dot, hosted molecular-beam epitaxy-grown $^{28}$Si/SiGe. The monotonically reproducibly tunable up to 15 % by gate voltages, originating 6 nm lateral displacement dot. We observe...
Silicon spin qubits stand out due to their very long coherence times, compatibility with industrial fabrication, and prospect integrate classical control electronics. To achieve a truly scalable architecture, coherent mid-range link that moves the electrons between qubit registers has been suggested solve signal fan-out problem. Here, we present blueprint of such $\approx 10\,\mu$m link, called shuttle, which is based on connecting an array gates into small number sets. these sets, only few...
We investigate the lifetime of two-electron spin states in a few-electron Si/SiGe double dot. At transition between (1,1) and (0,2) charge occupations, Pauli blockade provides readout mechanism for state. use statistics repeated single-shot measurements to extract lifetimes multiple simultaneously. When magnetic field is zero, we find that all three triplet have equal lifetimes, as expected, this time ~10 ms. nonzero, T(0) unchanged, whereas T- increases monotonically with field, reaching 3...
Si/SiGe heterostructures are of high interest for high-mobility transistor and qubit applications, specifically operations below $4.2\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. In order to optimize parameters such as charge mobility, built-in strain, electrostatic disorder, noise, valley splitting, these require Ge concentration profiles close monolayer precision. Ohmic contacts undoped usually facilitated by a global annealing step activating implanted dopants, but compromising the carefully...
High-fidelity control and unprecedented long dephasing times in silicon-based single spin qubits have recently confirmed the prospects of solid-state quantum computation. We investigate feasibility using a micro-magnet stray field for all-electrical, addressable qubit Si/SiGe double dot. For geometry optimized high Rabi-frequency, addressability, robustness to fabrication misalignment as previously demonstrated by Yoneda et al. [Phys. Rev. Lett. 113, 267601 (2014)], we simulate decoherence...
Abstract We identify the dominant source for low-frequency spin qubit splitting noise in a highly isotopically-purified silicon device with an embedded nanomagnet and echo decay time $${T}_{2}^{\,\text{echo}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> <mml:mspace /> <mml:mi>echo</mml:mi> </mml:msubsup> </mml:math> = 128 µs. The power spectral density (PSD) of charge explains both, clear transition...
A crucial requirement for quantum computing---in particular, scalable computing and error correction---is fast high-fidelity qubit readout. For semiconductor-based qubits, one limiting factor local low-power signal amplification is the output swing of charge sensor. We demonstrate $\mathrm{Ga}\mathrm{As}$ Si asymmetric sensing dots (ASDs) specifically designed to provide a significantly larger response compared conventional charge-sensing dots. Our ASD design features drain reservoir...
Silicon–germanium heterostructures are a promising quantum circuit platform, but crucial aspects, such as the long-term charge dynamics and cooldown-to-cooldown variations, still widely unexplored quantitatively. In this Letter, we present results of an extensive bias cooling study performed on gated silicon–germanium dots with Al2O3 dielectric. Over 80 cooldowns were in course our investigations. The performance devices is assessed by low-frequency noise measurements band 200 μHz to 10 mHz....
The continuous technological development of electronic devices and the introduction new materials lead to ever greater demands on fabrication semiconductor heterostructures their characterization. This work focuses optimizing Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) depth profiles aiming at a minimization measurement-induced profile broadening. As model system, state-of-the-art Molecular Beam Epitaxy (MBE) grown multilayer homostructure consisting natSi/28Si bilayers with...
Artificial molecules containing just one or two electrons provide a powerful platform for studies of orbital and spin quantum dynamics in nanoscale devices. A well-known example these is tunnelling between coupled dots triggered by microwave irradiation. So far, processes have been treated as electric-dipole-allowed spin-conserving events. Here we report that microwaves can also excite transitions states with different spin. We show the dominant mechanism responsible violation conservation...
For the realization of a quantum computer, good qubit design as basic building block is nontrivial starting point. To fully leverage potential computing, processors will likely have to incorporate billions high-quality qubits. Several approaches are being pursued and exhibit different strength weaknesses. The device concepts fabrication procedures for semiconductor based qubits very similar those used in industry. Using spin-degree freedom, their coherence properties quality single-qubit...
The lattice strain induced by metallic electrodes can impair the functionality of advanced quantum devices operating with electron or hole spins. Here, we investigate deformation CMOS-manufactured titanium nitride on a buried 10-nm-thick $\mathrm{Si}/{\mathrm{Si}}_{0.66}{\mathrm{Ge}}_{0.34}$ well means nanobeam scanning x-ray diffraction microscopy. We are able to measure $\mathrm{Ti}\mathrm{N}$-electrode-induced local modulations tensor components in range 2--8...
In this work, we study experimentally the impact of different gate dielectric stacks on subthreshold behavior cryogenic MOSFETs. While in room temperature devices, silicon nitride deteriorates off-state MOSFETs it turns out that at temperatures an appropriately thin, grown layer combination with a high-k counteracts saturation inverse slope and inflection phenomena. As result, steep strongly improved are demonstrated.
To use spin-flip photon-assisted tunneling (PAT) to couple two-electron spin states in quantum information processing, identifying its parameters is essential. The authors estimate the PAT coupling strength and relaxation dephasing timescales for double dots.