Charge qubit entanglement in double quantum dots

We study entanglement of charge qubits in a vertical tunnel-coupled double quantum dot containing two interacting electrons. Exact diagonalization is used to compute the negativity characterizing entanglement. We find that entanglement can be efficiently generated and controlled by sidegate voltages, and describe how it can be detected. For large enough tunnel coupling, the negativity shows a pronounced maximum at an intermediate interaction strength within the Wigner molecule regime.Comment: revised version of the manuscript, as published in EPL, 7 pages, 4 figure

Elastic Stars in General Relativity: II. Radial perturbations

We study radial perturbations of general relativistic stars with elastic matter sources. We find that these perturbations are governed by a second order differential equation which, along with the boundary conditions, defines a Sturm-Liouville type problem that determines the eigenfrequencies. Although some complications arise compared to the perfect fluid case, leading us to consider a generalisation of the standard form of the Sturm-Liouville equation, the main results of Sturm-Liouville theory remain unaltered. As an important consequence we conclude that the mass-radius curve for a one-parameter sequence of regular equilibrium models belonging to some particular equation of state can be used in the same well-known way as in the perfect fluid case, at least if the energy density and the tangential pressure of the background solutions are continuous. In particular we find that the fundamental mode frequency has a zero for the maximum mass stars of the models with solid crusts considered in Paper I of this series.Comment: 22 pages, no figures, final version accepted for publication in Class. Quantum Grav. The treatment of the junction conditions has been improve

DISSECTING THE REGISTRATION AND PROCESSING OF OLFACTORY EVENTS DURING GENERAL ANESTHESIA

It is commonly accepted that general anesthesia produces unconsciousness and amnesia. However, the extent to which the anesthetized brain receives and retains information is not well understood. Memory of a given event relies upon initial consolidation and subsequent retrieval. In order to test the effects of anesthesia on these separate memory components, we compared what rats reported behaviorally with what their brains 'reported' histologically. In chapter 2, we fully anesthetized rats with ketamine/xylazine anesthesia and exposed the animals to a novel odorant mixture. The following day the rats were presented with the same odorant mixture while awake in order to assess behavioral familiarity. The rats demonstrated no memory of the odorants previously presented during anesthesia. In order to assess odor-induced brain changes, rats were sacrificed for histological analysis 2 hours after exposure to the odorants during anesthesia, or 2 hours after re-exposure while awake the following day. We quantified the protein expression of c-fos, an immediate early gene thought to be critical for memory consolidation, in cortical olfactory regions. During anesthesia, a novel odorant mixture activated c-Fos similar to that found in awake animals. Repeated exposure to the odorants caused an attenuation of c-Fos regardless of whether the initial exposure occurred while anesthetized or awake. This suggests that memory-related protein changes can occur in olfactory cortical regions despite anesthesia. Given, the potential information consolidation observed in these ketamine/xylazine anesthetized animals, we attempted to retrieve olfactory memories using additional behavioral paradigms and memory-enhancing drugs in chapter 3, but were unable to reveal any explicit memory formation. However, we found subtle changes in odorant approach latency, suggesting a potential implicit memory. Further histological investigation in chapter 4 revealed that changes in odor-induced neurogenesis could also occur despite ketamine/xylazine anesthesia, similar to that found with c-Fos labeling, thus supporting the permissive role of this anesthetic. However, odor-related changes in c-Fos did not occur with the anesthetics pentobarbital or propofol, suggesting these traits are not universal amongst all anesthetics. Nevertheless, these data indicate a functional disconnection between the cortical representation of an environmental stimulus and the corresponding perceptual experience or memory

Two-particle Aharonov-Bohm effect and Entanglement in the electronic Hanbury Brown Twiss setup

We analyze a Hanbury Brown Twiss geometry in which particles are injected from two independent sources into a mesoscopic electrical conductor. The set-up has the property that all partial waves end in different reservoirs without generating any single particle interference. There is no single particle Aharonov-Bohm effect. However, exchange effects lead to two-particle Aharonov-Bohm oscillations in current correlations. We demonstrate that the two-particle Aharonov-Bohm effect is connected to orbital entanglement which can be used for violation of a Bell Inequality.Comment: 4 pages, 2 figures, discussion of postselected electron-electron entanglement adde

Andreev reflection eigenvalue density in mesoscopic conductors

The energy-dependent Andreev reflection eigenvalues determine the transport properties of normal-superconducting systems. We evaluate the eigenvalue density to get an insight into formation of resonant electron-hole transport channels. The circuit-theory-like method developed can be applied to any generic mesoscopic conductor or combinations thereof. We present the results for experimentally relevant cases of a diffusive wire and a double tunnel junction.Comment: 5 pages, 3 figure

Local and nonlocal entanglement for quasiparticle pairs induced by Andreev reflection

We investigate local and nonlocal entanglement of particle pairs induced by direct and crossed Andreev reflections at the interfaces between a superconductor and two normal conductors. It is shown theoretically that both local and nonlocal entanglement can be quantified by concurrence and detected from the violation of a Bell inequality of spin current correlators, which are determined only by normal reflection and Andreev reflection eigenvalues. There exists a one-to-one correspondence between the concurrence and the maximal Bell-CHSH parameter in the tunneling limit

Neurofilament light chain and total tau in the differential diagnosis and prognostic evaluation of acute and chronic inflammatory polyneuropathies

BACKGROUND AND PURPOSE: To investigate the diagnostic and prognostic value of axonal injury biomarkers in patients with inflammatory polyneuropathies. METHODS: Neurofilament light (NfL) chain and total tau (T-tau) were measured in the CSF and plasma in 41 patients with Guillain-Barré syndrome (GBS), 32 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 10 with paraproteinemia-related demyelinating polyneuropathy (PDN) and 8 with multifocal motor neuropathy (MMN), in comparison with 39 disease-free controls and 59 other controls. Outcome was measured with the GBS-disability score (GBS-ds) or Inflammatory Neuropathy Cause and Treatment (INCAT) disability score. RESULTS: NfL levels in CSF and plasma were higher in GBS, CIDP and PDN vs. disease-free controls. Patients with MMN had higher NfL levels in plasma vs. disease-free controls, but lower levels in CSF and plasma vs. patients with ALS. T-tau levels in plasma were higher in GBS, CIDP, PDN, and MMN vs. all control groups. NfL levels in CSF and plasma in patients with GBS correlated with GBS-ds, as higher levels were associated with inability to run after 6 and 12 months. NfL levels in CSF and plasma in CIDP did not correlate significantly with outcome. CONCLUSIONS: Acute and chronic inflammatory neuropathies are associated with increase in levels of NfL in CSF and plasma, but NfL is validated as a prognostic biomarker only in GBS. NfL could be used in differentiating patients with MMN from ALS. T-tau in plasma is a novel biomarker that could be used in a diagnostic assessment of patients with acute and chronic inflammatory polyneuropathies

Thouless energy of a superconductor from non local conductance fluctuations

We show that a spin-up electron from a normal metal entering a superconductor propagates as a composite object consisting of a spin-down hole and a pair in the condensate. This leads to a factorization of the non local conductance as two local Andreev reflections at both interfaces and one propagation in the superconductor, which is tested numerically within a one dimensional toy model of reflectionless tunneling. Small area junctions are characterized by non local conductance fluctuations. A treatment ignoring weak localization leads to a Thouless energy inverse proportional to the sample size, as observed in the numerical simulations. We show that weak localization can have a strong effect, and leads to a coupling between evanescent quasiparticles and the condensate by Andreev reflections ``internal'' to the superconductor.Comment: 11 pages, 12 figures, revised manuscrip

Nonequilibrium Josephson effect in short-arm diffusive SNS interferometers

We study non-equilibrium Josephson effect and phase-dependent conductance in three-terminal diffusive interferometers with short arms. We consider strong proximity effect and investigate an interplay of dissipative and Josephson currents co-existing within the same proximity region. In junctions with transparent interfaces, the suppression of the Josephson current appears at rather large voltage, $eV\sim \Delta$, and the current vanishes at $eV\geq\Delta$. Josephson current inversion becomes possible in junctions with resistive interfaces, where the inversion occurs within a finite interval of the applied voltage. Due to the presence of considerably large and phase-dependent injection current, the critical current measured in a current biased junction does not coincide with the maximum Josephson current, and remains finite when the true Josephson current is suppressed. The voltage dependence of the conductance shows two pronounced peaks, at the bulk gap energy, and at the proximity gap energy; the phase oscillation of the conductance exhibits qualitatively different form at small voltage $eV<\Delta$, and at large voltage $eV>\Delta$.Comment: 11 pages, 9 figures, revised version, to be published in Phys. Rev.