In-situ Tuning of the Electric Dipole Strength of a Double Dot Charge Qubit: Charge Noise Protection and Ultra Strong Coupling

Semiconductor quantum dots, where electrons or holes are isolated via electrostatic potentials generated by surface gates, are promising building blocks for semiconductor-based quantum technology. Here, we investigate double quantum dot (DQD) charge qubits in GaAs, capacitively coupled to high-impedance SQUID array and Josephson junction array resonators. We tune the strength of the electric dipole interaction between the qubit and the resonator in-situ using surface gates. We characterize the qubit-resonator coupling strength, qubit decoherence, and detuning noise affecting the charge qubit for different electrostatic DQD configurations. We find that all quantities can be tuned systematically over more than one order of magnitude, resulting in reproducible decoherence rates $\Gamma_2/2\pi<~5$ MHz in the limit of high interdot capacitance. Conversely, by reducing the interdot capacitance, we can increase the DQD electric dipole strength, and therefore its coupling to the resonator. By employing a Josephson junction array resonator with an impedance of $\sim4$ k$\Omega$ and a resonance frequency of $\omega_r/2\pi \sim 5.6$ GHz, we observe a coupling strength of $g/2\pi \sim 630$ MHz, demonstrating the possibility to achieve the ultrastrong coupling regime (USC) for electrons hosted in a semiconductor DQD. These results are essential for further increasing the coherence of quantum dot based qubits and investigating USC physics in semiconducting QDs.Comment: 24 pages, 13 figure

A critical evaluation of the Beckman Coulter Access hsTnI: analytical performance, reference interval and concordance

We investigated the analytical performance, outlier rate, carryover and reference interval of the Beckman Coulter Access hsTnI in detail and compared it with historical and other commercial assays.We compared the imprecision, detection capability, analytical sensitivity, outlier rate and carryover against two previous Access AccuTnI assay versions. We established the reference interval with stored samples from a previous study and compared the concordances and variances with the Access AccuTnI+3 as well as with two commercial assays.The Access hsTnI had excellent analytical sensitivity with the calibration slope 5.6 times steeper than the Access AccuTnI+3. The detection capability was markedly improved with the SD of the blank 0.18-0.20 ng/L, LoB 0.29-0.33 ng/L and LoD 0.58-0.69 ng/L. All the reference interval samples had a result above the LoB value. At a mean concentration of 2.83 ng/L the SD was 0.28 ng/L (CV 9.8%). Carryover (0.005%) and outlier (0.046%) rates were similar to the Access AccuTnI+3. The combined male and female 99th percentile reference interval was 18.2 ng/L (90% CI 13.2-21.1 ng/L). Concordance amongst the assays was poor with only 16.7%, 19.6% and 15.2% of samples identified by all 4 assays as above the 99th, 97.5th and 95th percentiles. Analytical imprecision was a minor contributor to the observed variances between assays.The Beckman Coulter Access hsTnI assay has excellent analytical sensitivity and precision characteristics close to zero. This allows cTnI measurement in all healthy individuals and the capability to identify numerically small differences between serial samples as statistically significant. Concordance in healthy individuals remains poor amongst assays

Observational Constraints on Interstellar Grain Alignment

We present new multicolor photo-polarimetry of stars behind the Southern Coalsack. Analyzed together with multiband polarization data from the literature, probing the Chamaeleon I, Musca, rho Opiuchus, R CrA and Taurus clouds, we show that the wavelength of maximum polarization (lambda_max) is linearly correlated with the radiation environment of the grains. Using Far-Infrared emission data, we show that the large scatter seen in previous studies of lambda_max as a function of A_V is primarily due to line of sight effects causing some A_V measurements to not be a good tracer of the extinction (radiation field strength) seen by the grains being probed. The derived slopes in lambda_max vs. A_V, for the individual clouds, are consistent with a common value, while the zero intercepts scale with the average values of the ratios of total-to-selective extinction (R_V) for the individual clouds. Within each cloud we do not find direct correlations between lambda_max and R_V. The positive slope in consistent with recent developments in theory and indicating alignment driven by the radiation field. The present data cannot conclusively differentiate between direct radiative torques and alignment driven by H_2 formation. However, the small values of lambda_max(A_V=0), seen in several clouds, suggest a role for the latter, at least at the cloud surfaces. The scatter in the lambda_max vs. A_V relation is found to be associated with the characteristics of the embedded Young Stellar Objects (YSO) in the clouds. We propose that this is partially due to locally increased plasma damping of the grain rotation caused by X-rays from the YSOs.Comment: Accepted for publication in the Astrophysical Journa

Impact of β-lactam antibiotic therapeutic drug monitoring on dose adjustments in critically ill patients undergoing continuous renal replacement therapy

The objective of this study was to describe the effect of therapeutic drug monitoring (TDM) and dose adjustments of β-lactam antibiotics administered to critically ill patients undergoing continuous renal replacement therapy (CRRT) in a 30-bed tertiary intensive care unit (ICU). β-Lactam TDM data in our tertiary referral ICU were retrospectively reviewed. Clinical, demographic and dosing data were collected for patients administered β-lactam antibiotics while undergoing CRRT. The target trough concentration range was 1–10× the minimum inhibitory concentration (MIC). A total of 111 TDM samples from 76 patients (46 male) with a mean ± standard deviation age of 56.6 ± 15.9 years and weight of 89.1 ± 25.8 kg were identified. The duration of antibiotic therapy was between 2 days and 42 days. TDM identified a need for dose modification of β-lactam antibiotics in 39 (35%) instances; in 27 (24%) samples, TDM values resulted in decreasing the prescribed dose of β-lactam antibiotic whereas an increase in the prescribed dose occurred in 12 (11%) cases. In patients treated for hospital-acquired pneumonia and primary or secondary bacteraemia, the dose was required to be decreased in 10/25 (40%) and 7/46 (15%) cases, respectively, to attain target concentrations. β-Lactam TDM is a useful tool for guiding drug dosing in complex patients such as those receiving CRRT. Although over one-third of patients manifested concentrations outside the therapeutic range, most of these CRRT patients had excessive β-lactam concentrations

Photon-mediated long range coupling of two Andreev level qubits

In a superconducting weak link, the supercurrent is carried by Andreev bound states (ABSs) formed by the phase-coherent reflection of electrons and their time-reversed partners. A single, highly transmissive ABS can serve as an ideal, compact two-level system, due to a potentially large energy difference to the next ABS. While the coherent manipulation of such Andreev levels qubits (ALQs) has been demonstrated, a long-range coupling between two ALQs, necessary for advanced qubit architectures, has not been achieved, yet. Here, we demonstrate a coherent remote coupling between two ALQs, mediated by a microwave photon in a novel superconducting microwave cavity coupler. The latter hosts two modes with different coupling rates to an external port. This allows us to perform fast readout of each qubit using the strongly coupled mode, while the weakly coupled mode is utilized to mediate the coupling between the qubits. When both qubits are tuned into resonance with the latter mode, we find excitation spectra with avoided-crossings, in very good agreement with the Tavis-Cummings model. Based on this model, we identify highly entangled two-qubit states for which the entanglement is mediated over a distance of six millimeters. This work establishes ALQs as compact and scalable solid-state qubits.Comment: 13 pages, 7 figure

Phase-dependent microwave response of a graphene Josephson junction

Gate-tunable Josephson junctions embedded in a microwave environment provide a promising platform to in situ engineer and optimize novel superconducting quantum circuits. The key quantity for the circuit design is the phase-dependent complex admittance of the junction, which can be probed by sensing a radio frequency SQUID with a tank circuit. Here, we investigate a graphene-based Josephson junction as a prototype gate-tunable element enclosed in a SQUID loop that is inductively coupled to a superconducting resonator operating at 3 GHz. With a concise circuit model that describes the dispersive and dissipative response of the coupled system, we extract the phase-dependent junction admittance corrected for self-screening of the SQUID loop. We decompose the admittance into the current-phase relation and the phase-dependent loss, and as these quantities are dictated by the spectrum and population dynamics of the supercurrent-carrying Andreev bound states, we gain insight to the underlying microscopic transport mechanisms in the junction. We theoretically reproduce the experimental results by considering a short, diffusive junction model that takes into account the interaction between the Andreev spectrum and the electromagnetic environment, from which we estimate lifetimes on the order of ∼10 ps for nonequilibrium populations

Phase-dependent microwave response of a graphene Josephson junction

Gate-tunable Josephson junctions embedded in a microwave environment provide a promising platform to in-situ engineer and optimize novel superconducting quantum circuits. The key quantity for the circuit design is the phase-dependent complex admittance of the junction, which can be probed by sensing an rf SQUID with a tank circuit. Here, we investigate a graphene-based Josephson junction as a prototype gate-tunable element enclosed in a SQUID loop that is inductively coupled to a superconducting resonator operating at 3 GHz. With a concise circuit model that describes the dispersive and dissipative response of the coupled system, we extract the phase-dependent junction admittance corrected for self-screening of the SQUID loop. We decompose the admittance into the current-phase relation and the phase-dependent loss and as these quantities are dictated by the spectrum and population dynamics of the supercurrent-carrying Andreev bound states, we gain insight to the underlying microscopic transport mechanisms in the junction. We theoretically reproduce the experimental results by considering a short, diffusive junction model that takes into account the interaction between the Andreev spectrum and the electromagnetic environment, from which we deduce a lifetime of ~17 ps for non-equilibrium populations

Rapid amino acid quantitation with pre-column derivatization; ultra-performance reverse phase liquid chromatography and single quadrupole mass spectrometry

Background: We optimized a quantitative amino acid method with pre-column derivatization, norvaline (nva) internal standard and reverse phase ultra-performance liquid chromatography by replacing the ultraviolet detector with a single quadrupole mass spectrometer (MSnva)

Calcium Carbonate Hexahydrate from Organic-Rich Sediments of the Antarctic Shelf: Precursors of Glendonites

Large euhedral crystals of calcium carbonate hexahydrate were recovered from a shelf basin of the Bransfield Strait, Antarctic Peninsula, at a water depth of 1950 meters and sub-zero bottom water temperatures. The chemistry, mineralogy, and stable isotope composition of this hydrated calcium carbonate phase, its environment of formation, and its mode of precipitation confirm the properties variously attributed to hypothetical precursors of the glendonites and thereby greatly expand their use in paleoceanographic interpretation

Banking union in historical perspective: the initiative of the European Commission in the 1960s-1970s

This article shows that planning for the organization of EU banking regulation and supervision did not just appear on the agenda in recent years with discussions over the creation of the eurozone banking union. It unveils a hitherto neglected initiative of the European Commission in the 1960s and early 1970s. Drawing on extensive archival work, this article explains that this initiative, however, rested on a number of different assumptions, and emerged in a much different context. It first explains that the Commission's initial project was not crisis-driven; that it articulated the link between monetary integration and banking regulation; and finally that it did not set out to move the supervisory framework to the supranational level, unlike present-day developments