271 research outputs found
Probing individual split Cooper-pairs using the spin qubit toolkit
A superconductor is a natural source of spin-entangled spatially separated
electron pairs. Although the first Cooper-pair splitter devices have been
realized recently, an experimental confirmation of the spin state and the
entanglement of the emitted electron pairs is lacking up to now. In this paper
a method is proposed to confirm the spin-singlet character of individual split
Cooper pairs. Two quantum dots (QDs), each of them holding one spin-prepared
electron, serve as the detector of the spin state of a single Cooper pair that
is forced to split when it tunnels out from the superconductor to the QDs. The
number of charges on the QDs, measured at the end of the procedure, carries
information on the spin state of the extracted Cooper pair. The method relies
on the experimentally established toolkit of QD-based spin qubits: resonant
spin manipulation, Pauli blockade, and charge measurement.Comment: 15 pages, 7 figure
Weltauflösungen
Nach dem Zweiten Weltkrieg zeichnet sich eine Krise der Erzählwelt in der deutschen und französischen Literatur ab. Erzähltexte, denen man Weltschöpfung zuschreibt, lösen nun Welten auf. Sie reagieren damit implizit auf ein wissenschaftliches Interesse an der Neuzeit, wie sie nach 1945 verhandelt wird. Daneben stellen instabile Erzählwelten eine Herausforderung für die heutige Methodologie der Erzählforschung dar.
Zwischen Wissenspoetologie und narratologischer Weltentheorie changierend, unternimmt die Arbeit den Versuch, Erzähltexte von Gottfried Benn, Arno Schmidt, Wolfgang Hildesheimer, Peter Weiss, Samuel Beckett, Alain Robbe-Grillet und Maurice Blanchot neu zu lesen. Ihre Texte werden so zum Ausgangspunkt einer Revision der Theorie erzählter Welten
Observation of spin-orbit coupling induced Weyl points and topologically protected Kondo effect in a two-electron double quantum dot
Recent years have brought an explosion of activities in the research of
topological aspects of condensed-matter systems. Topologically non-trivial
phases of matter are typically accompanied by protected surface states or
exotic degenerate excitations such as Majorana end states or Haldane's
localized spinons. Topologically protected degeneracies can, however, also
appear in the bulk. An intriguing example is provided by Weyl semimetals, where
topologically protected electronic band degeneracies and exotic surface states
emerge even in the absence of interactions. Here we demonstrate experimentally
and theoretically that Weyl degeneracies appear naturally in an interacting
quantum dot system, for specific values of the external magnetic field. These
magnetic Weyl points are robust against spin-orbit coupling unavoidably present
in most quantum dot devices. Our transport experiments through an InAs double
dot device placed in magnetic field reveal the presence of a pair of Weyl
points, exhibiting a robust ground state degeneracy and a corresponding
protected Kondo effect.Comment: 6 pages, 3 figures. Supplementary Information can be downloaded as an
ancillary pdf fil
Strong nonlocal tuning of the current-phase relation of a quantum dot based Andreev molecule
Multiple systems hosting Andreev molecular states have been proposed and
studied, consisting of closely spaced Josephson junctions modeled as ballistic
channels. We show that replacing the ballistic channels in the weak link of the
Josephson junctions with quantum dots (QD), leads to a very exciting, rich
phase diagram. It shows a strong nonlocal Josephson effect: as one junction is
tuned the current-phase relation of the other junction is modified. This
architecture hosts transitions and shows a tunable anomalous
phase-shift , nonlocally controlled in both cases, without relying on
spin-orbit interaction or Zeeman fields. In addition significant
superconducting diode effect can also be observed. The presented non-local
current-phase relation can be used as a signature of the formation of an
Andreev molecular state, as well as to introduce new ways to tune quantum
architectures
Colocalization of endogenous TNF with a functional intracellular splice form of human TNF receptor type 2
BACKGROUND: Tumor necrosis factor (TNF) is a pleiotropic cytokine involved in a broad spectrum of inflammatory and immune responses including proliferation, differentiation, and cell death. The biological effects of TNF are mediated via two cell surface TNF receptors: p55TNFR (TNFR1; CD120a) and p75TNFR (TNFR2; CD120b). Soluble forms of these two receptors consisting of the extracellular domains are proteolytically cleaved from the membrane and act as inhibitors. A novel p75TNFR isoform generated by the use of an additional transcriptional start site has been described and was termed hicp75TNFR. We focused on the characterization of this new isoform as this protein may be involved in chronic inflammatory processes. METHODS: Cell lines were retroviraly transduced with hp75TNFR isoforms. Subcellular localization and colocalization studies with TNF were performed using fluorescence microscopy including exhaustive photon reassignment software, flow cytometry, and receptosome isolation by magnetic means. Biochemical properties of the hicp75TNFR were determined by affinity chromatography, ELISA, and western blot techniques. RESULTS: We describe the localization and activation of a differentially spliced and mainly intracellularly expressed isoform of human p75TNFR, termed hicp75TNFR. Expression studies with hicp75TNFR cDNA in different cell types showed the resulting protein mostly retained in the trans-Golgi network and in endosomes and colocalizes with endogenous TNF. Surface expressed hicp75TNFR behaves like hp75TNFR demonstrating susceptibility for TACE-induced shedding and NFκB activation after TNF binding. CONCLUSION: Our data demonstrate that intracellular hicp75TNFR is not accessible for exogenously provided TNF but colocalizes with endogenously produced TNF. These findings suggest a possible intracellular activation mechanism of hicp75TNFR by endogenous TNF. Subsequent NFκB activation might induce anti-apoptotic mechanisms to protect TNF-producing cells from cytotoxic effects of TNF. In addition, the intracellular and not TACE-accessible splice form of the hp75TNFR could serve as a pool of preformed, functional hp75TNFR
Primary structure and functional expression of a cyclic nucleotidegated channel from rabbit aorta
Sequences specific for cyclic nucleotide-gated channels (CNG channels) have been amplified by PCR from cDNA of heart, aorta, sinoatrial node, cerebellum, C-cells and kidney. The complete amino acid sequence of a CNG channel from rabbit aorta has been deduced by cloning and sequence analysis of the cDNA. Synthetic RNA derived from this cDNA induces the formation of a functional CNG channel in Xenopus oocytes
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