University of Stuttgart

About: University of Stuttgart is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Laser & Finite element method. The organization has 27715 authors who have published 56370 publications receiving 1363382 citations. The organization is also known as: Universität Stuttgart.

Mutant analysis links the translocon and BiP to retrograde protein transport for ER degradation

Abstract: Proteins enter the secretory pathway through the endoplasmic reticulum1, which delivers properly folded proteins to their site of action2 and contains a quality-control system to monitor and prevent abnormal proteins from being delivered3. Many of these proteins are degraded by the cytoplasmic proteasome4,5,6,7,8, which requires their retrograde transport to the cytoplasm5,6. Based on a co-immunoprecipitation of major histocompatibility complex (MHC) class I heavy-chain breakdown intermediates with the translocon subunit Sec61p (refs 9, 10), it was speculated that Sec61p may be involved in retrograde transport11. Here we present functional evidence from genetic studies that Sec61p mediates retrograde transport of a mutated lumenal yeast carboxypeptidase ycsY (CPY*) in vivo. The endoplasmic reticulum lumenal chaperone BiP (Kar2p) and Sec63p, which are also subunits of the import machinery10,12, are involved in export of CPY* to the cytosol. Thus our results demonstrate that retrograde transport of proteins is mediated by a functional translocon. We consider the export of endoplasmic reticulum-localized proteins to the cytosol by the translocon for proteasome degradation to be a general process in eukaryotic cell biology.

Reduction of oscillator strength due to piezoelectric fields in G a N / A l x Ga 1 − x N quantum wells

Abstract: We demonstrate a dramatic reduction of the oscillator strength in ${\mathrm{G}\mathrm{a}\mathrm{N}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ quantum wells due to piezoelectric fields. Our study using time-resolved photoluminescence spectroscopy reveals a strong increase of the luminescence decay time of the dominating transition with increasing well width by several orders of magnitude in parallel to a redshift of the emission peaks. The experimental results are consistently explained by a quantitative model based on the piezoelectric fields in strained wurtzite quantum wells. We estimate the piezoelectric constant of GaN to ${d}_{31}=\ensuremath{-}0.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ cm/V.

Quantum error correction in a solid-state hybrid spin register

Abstract: Error correction is important in classical and quantum computation Decoherence caused by the inevitable interaction of quantum bits with their environment leads to dephasing or even relaxation Correction of the concomitant errors is therefore a fundamental requirement for scalable quantum computation Although algorithms for error correction have been known for some time, experimental realizations are scarce Here we show quantum error correction in a heterogeneous, solid-state spin system We demonstrate that joint initialization, projective readout and fast local and non-local gate operations can all be achieved in diamond spin systems, even under ambient conditions High-fidelity initialization of a whole spin register (99 per cent) and single-shot readout of multiple individual nuclear spins are achieved by using the ancillary electron spin of a nitrogen-vacancy defect Implementation of a novel non-local gate generic to our electron-nuclear quantum register allows the preparation of entangled states of three nuclear spins, with fidelities exceeding 85 per cent With these techniques, we demonstrate three-qubit phase-flip error correction Using optimal control, all of the above operations achieve fidelities approaching those needed for fault-tolerant quantum operation, thus paving the way to large-scale quantum computation Besides their use with diamond spin systems, our techniques can be used to improve scaling of quantum networks relying on phosphorus in silicon, quantum dots, silicon carbide or rare-earth ions in solids

Transition from Isolated to Collective Modes in Plasmonic Oligomers

Abstract: We demonstrate the transition from isolated to collective optical modes in plasmonic oligomers. Specifically, we investigate the resonant behavior of planar plasmonic hexamers and heptamers with gradually decreasing the interparticle gap separation. A pronounced Fano resonance is observed in the plasmonic heptamer for separations smaller than 60 nm. The spectral characteristics change drastically upon removal of the central nanoparticle. Our work paves the road toward complex hierarchical plasmonic oligmers with tailored optical properties.