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The discovery of the Stern-Gerlach (SG) effect almost a century ago was followed by suggestions to use the effect as a basis for matter-wave interferometry. However, the coherence of splitting particles with spin by a magnetic gradient to a distance exceeding the position uncertainty in each of the arms was not demonstrated until recently, where spatial interference fringes were observed in a proof-of-principle experiment. Here we present and analyze the performance of an improved high-stability SG spatial fringe interferometer based on two spatially separate wave packets with a maximal distance that is more than an order of magnitude larger than their minimal widths. The improved performance is enabled by accurate magnetic field gradient pulses, originating from a novel atom chip configuration, which ensures high stability of the interferometer operation. We analyze the achieved stability using several models, discuss sources of noise, and detail interferometer optimization procedures. We also present a simple analytical phase-space description of the interferometer sequence that demonstrates quantitatively the complete separation of the superposed wave packets2.

A compact detector for space-time metric and curvature is highly desirable. Here we show that quantum spatial superpositions of mesoscopic objects could be exploited to create such a detector. We propose a specific form for such a detector and analyse how asymmetries in its design allow it to directly couple to the curvature. Moreover, we also find that its non-symmetric construction and the large mass of the interfered objects, enable the detection gravitational waves (GWs). Finally, we discuss how the construction of such a detector is in principle possible with a combination of state of the art techniques while taking into account the known sources of decoherence and noise. To this end, we use Stern-Gerlach interferometry with masses ∼10−17 kg, where the interferometric signal is extracted by measuring spins and show that accelerations as low as 5 × 10−15  ms−2 Hz−1/2, as well as the frame dragging effects caused by the Earth, could be sensed. The GW sensitivity scales differently from the stray acceleration sensitivity, a unique feature of the proposed interferometer. We identify mitigation mechanisms for the known sources of noise, namely gravity gradient noise, uncertainty principle and electro-magnetic forces and show that it could potentially lead to a metre sized, orientable and vibrational noise (thermal/seismic) resilient detector of mid (ground based) and low (space based) frequency GWs from massive binaries (the predicted regimes are similar to those targeted by atom interferometers and LISA).

The Christian nationalist Doug Wilson says he isn’t trying to be Howard Stern but his language can be just as controversial. On this week’s “Interesting Times,” he defends his use of “naughty words” as weapons in his arsenal.

Quantum optimal control, a toolbox for devising and implementing the shapes of external fields that accomplish given tasks in the operation of a quantum device in the best way possible, has evolved into one of the cornerstones for enabling quantum technologies. The last few years have seen a rapid evolution and expansion of the field. We review here recent progress in our understanding of the controllability of open quantum systems and in the development and application of quantum control techniques to quantum technologies. We also address key challenges and sketch a roadmap for future developments.

Water-lubricated stern bearing (WSB) is a vital part of the ship propulsion-shaft system, and it is of great significance to monitor and analyze its lubrication status through film thickness data to improve the equipment operational reliability. In this paper, a full-size, large length-to-diameter ratio WSB experiment is carried out, and multi-sectional journal displacement data are collected under offset load. Accordingly, a bearing film-thickness identification model is established, which can identify the dynamic film thickness data in the circumferential direction of bearing section by limited measurement points. On this basis, the film thickness distribution of the full bearing is obtained by combining finite element (FE) simulation and particle swarm optimization (PSO) algorithm. The effect of different speeds on the distributed lubrication characteristics of WSB under offset load was systematically analyzed based on film thickness data. Results show that the maximum identification error of the bearing film-thickness identification model is less than 7%. The bearing lubrication state changes dynamically as the speed increases, and the hydrodynamic lubrication effect in the middle of the bearing is enhanced. The area of each lubrication sub-region varies nonlinearly. Research results are instructive for further determine the service life of the shaft system.

We present a feasibility study with several magnetic field configurations for creating spin-dependent forces that can split a low-energy ion beam by the Stern-Gerlach (SG) effect. To the best of our knowledge, coherent spin-splittings of charged particles have yet to be realised. Our proposal is based on ion source parameters taken from a recent experiment that demonstrated single-ion implantation from a high-brightness ion source combined with a radio-frequency Paul trap. The inhomogeneous magnetic fields can be created by permanently magnetised microstructures or from current-carrying wires with sizes in the micron range, such as those recently used in a successful implementation of the SG effect with neutral atoms. All relevant forces (Lorentz force and image charges) are taken into account, and measurable splittings are found by analytical and numerical calculations.

The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents the central element of electrochemical supercapacitors. The surface potential of such surfaces generally exceeds the electrokinetic potential, often substantially. Traditionally, a Stern layer of nonspecifically adsorbed ions has been invoked to rationalize the difference between these two potentials; however, the inability to directly measure the surface potential of dispersed systems has rendered quantitative measurements of the Stern layer potential, and other quantities associated with the outer Helmholtz plane, impossible. Here, we use x-ray photoelectron spectroscopy from a liquid microjet to measure the absolute surface potentials of silica nanoparticles dispersed in aqueous electrolytes. We quantitatively determine the impact of specific cations (Li+ , Na+ , K+ , and Cs+ ) in chloride electrolytes on the surface potential, the location of the shear plane, and the capacitance of the Stern layer. We find that the magnitude of the surface potential increases linearly with the hydrated-cation radius. Interpreting our data using the simplest assumptions and most straightforward understanding of Gouy-Chapman-Stern theory reveals a Stern layer whose thickness corresponds to a single layer of water molecules hydrating the silica surface, plus the radius of the hydrated cation. These results subject electrical double-layer theories to direct and falsifiable tests to reveal a physically intuitive and quantitatively verified picture of the Stern layer that is consistent across multiple electrolytes and solution conditions.

In a planing vessel, an interceptor is used to exercise control trim at a limited speed, which can result in excessive drag and bow trim at high speed. Previous studies have combined interceptors with stern flaps to achieve optimal hydrodynamic performance on planing hulls. This study investigated the hydrodynamic characteristics of a planing hull with an integrated interceptor-stern flap. The integrated interceptor-stern flap is a form of integration between the interceptor, which is mounted downwards and vertically on the transom, and the stern flap at the end. At high speed, the same interceptor (i) height converted to an integrated interceptor-stern flap can produce better results. Different flap angles were considered to affect interceptor performance. The fluid flow around the ship model was solved using the Reynolds-Average Navier-Stokes equation and the realizable k-epsilon turbulence model technique. The total number of meshes was determined using mesh independence. In conclusion, while the interceptor showcased significant reductions in resistance and trim across various Froude numbers, its effectiveness was compromised at high speeds due to increased drag and trim height, necessitating caution in its application. Furthermore, integrating stern flaps with the interceptor, particularly with a 5° angle, proved promising in further reducing drag and trim, highlighting the importance of interceptor design considerations for enhancing ship performance.

Yellow-emissive carbon dots (Y-CDs) were prepared by a solvothermal method using anhydrous citric acid and 2,3-phenazinediamine as the starting materials. The Y-CDs display a 24% fluorescence quantum yield, a 188-nm Stokes’ shift and excellent stability. They are shown here to be excellent fluorescent probes for the determination of Ag(I) ion and glutathione (GSH). If exposed to Ag(I) ions, they are bound by the carboxy groups of the Y-CDs, and this causes quenching of fluorescence (with excitation/emission maxima at 380/568 nm) via a static quenching mechanism. This effect was used to design a fluorometric assay for Ag(I). The quenched fluorescence of the Y-CDs can be restored by adding GSH due to the high affinity of GSH for Ag(I). The calibration plot for Ag(I) is linear in the 1–4 μM Ag(I) concentration range, and the limit of detection is 31 nM. The respective values for GSH are 5–32 μM, and 76 nM, respectively. The method was applied to the detection of Ag(I) in spiked environmental water samples and gave recoveries ranging from 93 to 107%. It was also applied to the determination of GSH in tomatoes and purple grapes and gave satisfactory recoveries. The Y-CDs display low cytotoxicity and were successfully used to image Ag(I) and GSH in H1299 cells. Graphical abstract Schematic presentation of the mechanism of yellow fluorescent CDs for the detection of Ag + and glutathione.