Buried-channel semiconductor heterostructures are an archetype material platform for the fabrication of gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface; however, nearby surface states degrade the electrical properties of the starting material. Here, a 2D hole gas of high mobility (5 × 10 5 cm 2 V −1 s −1 ) is demonstrated in a very shallow strained germanium (Ge) channel, which is located only 22 nm below the surface. The top-gate of a dopant-less field effect transistor controls the channel carrier density confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The high mobility leads to mean free paths ≈ 6 µm, setting new benchmarks for holes in shallow field effect transistors. The high mobility, along with a percolation density of 1.2 × 10 11 cm −2 , light effective mass (0.09m e ), and high effective g-factor (up to 9.2) highlight the potential of undoped Ge/SiGe as a low-disorder material platform for hybrid quantum technologies.

Superconductors and semiconductors are crucial platforms in the field of quantum computing. They can be combined to hybrids, bringing together physical properties that enable the discovery of new emergent phenomena and provide novel strategies for quantum control. The involved semiconductor materials, however, suffer from disorder, hyperfine interactions or lack of planar technology. Here we realise an approach that overcomes these issues altogether and integrate gate-defined quantum dots and superconductivity into germanium heterostructures. In our system, heavy holes with mobilities exceeding 500,000 cm2 (Vs)−1 are confined in shallow quantum wells that are directly contacted by annealed aluminium leads. We observe proximity-induced superconductivity in the quantum well and demonstrate electric gate-control of the supercurrent. Germanium therefore has great promise for fast and coherent quantum hardware and, being compatible with standard manufacturing, could become a leading material for quantum information processing.

The current implementation into nephrology clinical practice of guidelines on treatment of cardiovascular (CV) risk factors in chronic kidney disease (CKD) is unknown. We designed a cross-sectional analysis to evaluate the prevalence and treatment of eight modifiable CV risk factors in 1058 predialysis CKD patients (stage 3: n=486; stage 4: n=430, stage 5: n=142) followed for at least 1 year in 26 Italian renal clinics. The median nephrology follow-up was 37 months (range: 12-391 months). From stages 3 to 5, hypertension was the main complication (89, 87, and 87%), whereas smoking, high calcium-phosphate product and malnutrition were uncommon. The prevalence of proteinuria (25, 38, and 58%), anemia (16, 32, and 51%) and left ventricular hypertrophy (51, 55, and 64%) significantly increased, while hypercholesterolemia was less frequent in stage 5 (49%) than in stages 4 and 3 (59%). The vast majority of patients received multidrug antihypertensive therapy including inhibitors of renin-angiotensin system; conversely, diuretic treatment was consistently inadequate for both frequency and dose despite scarce implementation of low salt diet (19%). Statins were not prescribed in most hypercholesterolemics (78%), and epoietin treatment was largely overlooked in anemics (78%). The adjusted risk for having a higher number of uncontrolled risk factors rose in the presence of diabetes (odds ratio 1.29, 95% confidence interval 1.00-1.66), history of CV disease (odds ratio 1.48, 95% confidence interval 1.15-1.90) and CKD stages 4 and 5 (odds ratio 1.75, 95% confidence interval 1.37-2.22 and odds ratio 2.85, 95% confidence interval 2.01-4.04, respectively). In the tertiary care of CKD, treatment of hypertension is largely inadequate, whereas therapy of anemia and dyslipidemia is frequently omitted. The risk of not achieving therapeutic targets is higher in patients with diabetes, CV disease and more advanced CKD.

Heavily-doped semiconductor films are very promising for application in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in this wavelength range. In this work we investigate heavily n-type doped germanium epilayers grown on different substrates, in-situ doped in the 10 17 to 10 19 cm −3 range, by infrared spectroscopy, first principle calculations, pump-probe spectroscopy and dc transport measurements to determine the relation between plasma edge and carrier density and to quantify mid-infrared plasmon losses. We demonstrate that the unscreened plasma frequency can be tuned in the 400 -4800 cm −1 range and that the average electron scattering rate, dominated by scattering with optical phonons and charged impurities, increases almost linearly with frequency. We also found weak dependence of losses and tunability on the crystal defect density, on the inactivated dopant density and on the temperature down to 10 K. In films where the plasma was optically activated by pumping in the near-infrared, we found weak but significant dependence of relaxation times on the static doping level of the film. Our results suggest that plasmon decay times in the several-picosecond range can be obtained in ntype germanium thin films grown on silicon substrates hence allowing for underdamped mid-infrared plasma oscillations at room temperature.The recent push towards applications of spectroscopy for chemical and biological sensing in the mid-infrared (mid-IR)1-8 has prompted the need for conducting thin films displaying values of the complex dielectric functionǫ(ω) = ǫ ′ (ω) + iǫ ′′ (ω) that can be tailored to meet the needs of novel electromagnetic designs exploiting the concepts of metamaterials, transformation optics and plasmonics 9 . In the design of metamaterials, where subwavelength sized conducting elements are embedded in dielectric matrices, if the values of ǫ ′ of the metal and the dielectric are of the same order, but have opposite sign, the geometric filling fractions of the metal and dielectric can be readily tuned to achieve subwavelengthresolution focusing of radiation 10 . Such requirement is met by silver for wavelengths λ around 400 nm. The same condition cannot be achieved in the IR range by using elemental metals, however, because metals possess an extremely high negative value of ǫ ′ not equaled, in

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