149 research outputs found
High mobility SiMOSFETs fabricated in a full 300mm CMOS process
The quality of the semiconductorâbarrier interface plays a pivotal role in the demonstration of high quality reproducible quantum dots for quantum information processing. In this work, we have measured SiMOSFET Hall bars on undoped Si substrates in order to investigate the device quality. For devices fabricated in a full complementary metal oxide semiconductor (CMOS) process and of very thin oxide below a thickness of 10 nm, we report a record mobility of 17.5 Ă 103 cm2 Vâ1 sâ1 indicating a high quality interface, suitable for future qubit applications. We also study the influence of gate materials on the mobilities and discuss the underlying mechanisms, giving insight into further material optimization for large scale quantum processors
Modelling semiconductor spin qubits and their charge noise environment for quantum gate fidelity estimation
The spin of an electron confined in semiconductor quantum dots is currently a
promising candidate for quantum bit (qubit) implementations. Taking advantage
of existing CMOS integration technologies, such devices can offer a platform
for large scale quantum computation. However, a quantum mechanical framework
bridging a device's physical design and operational parameters to the qubit
energy space is lacking. Furthermore, the spin to charge coupling introduced by
intrinsic or induced Spin-Orbit-Interaction (SOI) exposes the qubits to charge
noise compromising their coherence properties and inducing quantum gate errors.
We present here a co-modelling framework for double quantum dot (DQD) devices
and their charge noise environment. We use a combination of an electrostatic
potential solver, full configuration interaction quantum mechanical methods and
two-level-fluctuator models to study the quantum gate performance in realistic
device designs and operation conditions. We utilize the developed models
together alongside the single electron solutions of the quantum dots to
simulate one- and two- qubit gates in the presence of charge noise. We find an
inverse correlation between quantum gate errors and quantum dot confinement
frequencies. We calculate X-gate fidelities >97% in the simulated Si-MOS
devices at a typical TLF densities. We also find that exchange driven two-qubit
SWAP gates show higher sensitivity to charge noise with fidelities down to 91%
in the presence of the same density of TLFs. We further investigate the one-
and two- qubit gate fidelities at different TLF densities. We find that given
the small size of the quantum dots, sensitivity of a quantum gate to the
distance between the noise sources and the quantum dot creates a strong
variability in the quantum gate fidelities which can compromise the device
yields in scaled qubit technologies.Comment: 23 pages , 16 figure
Near-field interactions between metal nanoparticle surface plasmons and molecular excitons in thin-films: part I: absorption
In this and the following paper (parts I and II, respectively), we systematically study the interactions between surface plasmons of metal nanoparticles (NPs) with excitons in thin-films of organic media. In an effort to exclusively probe near-field interactions, we utilize spherical Ag NPs in a size-regime where far-field light scattering is negligibly small compared to absorption. In part I, we discuss the effect of the presence of these Ag NPs on the absorption of the embedding medium by means of experiment, numerical simulations, and analytical calculations, all shown to be in good agreement. We observe absorption enhancement in the embedding medium due to the Ag NPs with a strong dependence on the medium permittivity, the spectral position relative to the surface plasmon resonance frequency, and the thickness of the organic layer. By introducing a low index spacer layer between the NPs and the organic medium, this absorption enhancement is experimentally confirmed to be a near field effect In part II, we probe the impact of the Ag NPs on the emission of organic molecules by time-resolved and steady-state photoluminescence measurements
Functional characterization of the first missense variant in <i>CEP78</i>, a founder allele associated with cone-rod dystrophy, hearing loss and reduced male fertility
Inactivating variants in the centrosomal CEP78 gene have been found in cone-rod dystrophy with hearing loss (CRDHL), a particular phenotype distinct from Usher syndrome. Here, we identified and functionally characterized the first CEP78 missense variant c.449T>C, p.(Leu150Ser) in three CRDHL families. The variant was found in a biallelic state in two Belgian families and in a compound heterozygous state-in trans with c.1462-1G>T-in a third German family. Haplotype reconstruction showed a founder effect. Homology modeling revealed a detrimental effect of p.(Leu150Ser) on protein stability, which was corroborated in patients' fibroblasts. Elongated primary cilia without clear ultrastructural abnormalities in sperm or nasal brushes suggest impaired cilia assembly. Two affected males from different families displayed sperm abnormalities causing infertility. One of these is a heterozygous carrier of a complex allele in SPAG17, a ciliary gene previously associated with autosomal recessive male infertility. Taken together, our data indicate that a missense founder allele in CEP78 underlies the same sensorineural CRDHL phenotype previously associated with inactivating variants. Interestingly, the CEP78 phenotype has been possibly expanded with male infertility. Finally, CEP78 loss-of-function variants may have an underestimated role in misdiagnosed Usher syndrome, with or without sperm abnormalities
Spintronics: Fundamentals and applications
Spintronics, or spin electronics, involves the study of active control and
manipulation of spin degrees of freedom in solid-state systems. This article
reviews the current status of this subject, including both recent advances and
well-established results. The primary focus is on the basic physical principles
underlying the generation of carrier spin polarization, spin dynamics, and
spin-polarized transport in semiconductors and metals. Spin transport differs
from charge transport in that spin is a nonconserved quantity in solids due to
spin-orbit and hyperfine coupling. The authors discuss in detail spin
decoherence mechanisms in metals and semiconductors. Various theories of spin
injection and spin-polarized transport are applied to hybrid structures
relevant to spin-based devices and fundamental studies of materials properties.
Experimental work is reviewed with the emphasis on projected applications, in
which external electric and magnetic fields and illumination by light will be
used to control spin and charge dynamics to create new functionalities not
feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes
from the published versio
Epidermal Growth Factor Receptor and K-RAS status in two cohorts of squamous cell carcinomas
With the availability of effective anti-EGFR therapies for various solid malignancies, such as non-cell small lung cancer, colorectal cancer and squamous cell carcinoma of the head and neck, the knowledge of EGFR and K-RAS status becomes clinically important. The aim of this study was to analyse EGFR expression, EGFR gene copy number and EGFR and K-RAS mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas.Journal ArticleMulticenter StudyResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe
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