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Constrained many-body phases in a -Higgs lattice gauge theory
No full textWe study the ground-state phase diagram of a one-dimensional lattice gauge theory coupled to soft-core bosonic matter at unit filling, inspired by the Higgs sector of the standard model. Through a combination of analytical perturbative approaches, exact diagonalization, and density-matrix-renormalization-group simulations, we uncover a rich phase diagram driven by gauge-field-mediated resonant pair hopping and the confinement of single particles. The pair hopping results in a bunching state with superextensive energy and macroscopic particle number fluctuations at strong electric field strengths and weak on-site interactions. The bunching state crosses over into a pair superfluid phase as the on-site interaction increases, characterized by a finite superfluid density and powerlaw-decaying pair correlations. At large on-site interaction strengths and driven by effective interactions induced by the gauge constraint, the superfluid transitions into an incompressible pair Mott insulator phase. At weak field strengths and on-site interactions, we find a plasma-like region, where single bosons exhibit large short-range correlations and the ground state is composed almost equally of states with even and odd local boson occupation. The presence of a bunching state with large number fluctuations, which is difficult to study using classical numerics, motivates experimental realizations in hybrid boson-qubit quantum simulation platforms such as circuit QED, neutral atoms, and trapped ions. Our findings highlight the rich interplay between gauge fields and soft-core bosonic matter
Matching Lagrangian and Hamiltonian Simulations in (2+1)-dimensional U(1) Gauge Theory
No full textAt finite lattice spacing, Lagrangian and Hamiltonian predictions differ due to discretization effects. In the Hamiltonian limit, i.e. at vanishing temporal lattice spacing , the path integral approach in the Lagrangian formalism reproduces the results of the Hamiltonian theory. In this work, we numerically calculate the Hamiltonian limit of a U gauge theory in dimensions. This is achieved by Monte Carlo simulations in the Lagrangian formalism with lattices that are anisotropic in the time direction. For each ensemble, we determine the ratio between the temporal and spatial scale with the static quark potential and extrapolate to . Our results are compared with the data from Hamiltonian simulations at small volumes, showing agreement within . These results can be used to match the two formalisms
Quantum Natural Gradient with Geodesic Corrections for Small Shallow Quantum Circuits
No full textThe Quantum Natural Gradient (QNG) method enhances optimizationin variational quantum algorithms (VQAs) by incorporating geometric insights fromthe quantum state space through the Fubini-Study metric. In this work, we extendQNG by introducing higher-order integrators and geodesic corrections using theRiemannian Euler update rule and geodesic equations, deriving an updated rule for theQuantum Natural Gradient with Geodesic Correction (QNGGC). We also develop anefficient method for computing the Christoffel symbols necessary for these corrections,leveraging the parameter-shift rule to enable direct measurement from quantumcircuits. Through theoretical analysis and practical examples, we demonstrate thatQNGGC significantly improves convergence rates over standard QNG, highlightingthe benefits of integrating geodesic corrections into quantum optimization processes.Our approach paves the way for more efficient quantum algorithms, leveraging theadvantages of geometric methods
A High-Flux Electron Detector System to Measure Non-linear Compton Scattering at LUXE
No full textRecently, advancements in high-intensity laser technology have enabled the exploration of non-perturbative Quantum Electrodynamics(QED) in strong-field regimes. Notable aspects include non-linear Compton scattering and Breit-Wheeler pair production, observablewhen colliding high-intensity laser pulses and relativistic electron beams. The LUXE experiment at DESY and the E-320 experimentat SLAC aim to study these phenomena by measuring the created high-flux Compton electrons and photons. We propose a noveldetector system featuring a segmented gas-filled Cherenkov detector with a scintillator screen and camera setup, designed toefficiently detect high-flux Compton electrons. Preliminary results from E-320 measurement campaigns demonstrate methods forreconstructing electron energy spectra, aiming to reveal crucial features of non-perturbative QED
Post hot-deformation precipitation behavior of γ′ phase in VDM® alloy 780 under varying cooling rates and aging temperatures: An in situ high energy XRD study
No full textThe performance of polycrystalline Ni-based superalloys is largely determined by the fraction and size of theintermetallic hardening phases, such as the γ′ phase. Understanding the evolution of the γ′ precipitate size andvolume fraction during the complex thermomechanical process chain is essential for optimizing the mechanicalproperties of polycrystalline Ni-based superalloys. In this study, the high temporal resolution of in situ synchrotronX-ray diffraction at elevated temperatures was used to monitor γ′ evolution in VDM® Alloy 780 duringcooling and subsequent aging heat treatments in real time. To simulate the industrial forging process, the alloywas initially subjected to compressive deformation at 1000 ◦C. In the first part of the study, immediately after hotforming, three different cooling rates (10 ◦C/min, 100 ◦C/min, and 1000 ◦C/min) were applied to analyse the insitu evolution of γ′ precipitation. The resulting γ′ phase fraction was highest at the slowest cooling rate, yet eventhe fastest cooling rate did not completely suppress precipitation. In the second part of the study, the agehardeningresponse of the alloy was examined at holding temperatures of 720 ◦C and 800 ◦C for five hourseach. The evolution of the γ′ volume fraction, precipitate size, and lattice parameter was monitored in situ byXRD. After aging, γ′ volume fractions of 15 % and 19 % were obtained, with average precipitate sizes of 9 nm and18 nm, respectively. The prior deformation enhanced γ′ formation at 720 ◦C compared to literature data.Complementary Transmission Electron Microscopy (TEM) measurements confirmed precipitate sizes consistentwith the diffraction data.1. IntroductionHigher operating temperatures in both jet engines and stationary gasturbines are required to increase their efficiency, i.e., to reduce CO2emissions and fulfill the European Green Deal. Polycrystalline Ni-basedsuperalloys are inevitable for such challenging applications where thematerial is subjected to a combination of high thermal and mechanicalloads in corrosive environments [1–3]. The workhorse of polycrystallineNi-based superalloys is Alloy 718, commonly known as Inconel; however,its application temperature is limited to 650 ◦C [4,5].To increase the possible application temperatures and yield higherefficiencies, the VDM® Alloy 780 (DIN no. 2.4960) was developed forapplications at temperatures of up to 750 ◦C under high mechanical
Structure‐based discovery of thiamine uptake inhibitors
No full textBackground and PurposeThiamine (vitamin B1) is an essential coenzyme and catalyses various reactions in central metabolic pathways. Since mammals have lost the ability to synthesise thiamine de novo, this micronutrient has to be imported via the high affinity solute carriers SLC19A2 and A3 across the plasma membrane. Perturbations of these transport systems have severe effects on human health. Recent structural work on SLC19A2 and A3 have provided molecular insights into substrate and drug recognition and conformational changes during transport. Based on the analysis of the available SLC19A3 structures, we hypothesise that the binding site is rather promiscuous, allowing different small molecules to interact and potentially inhibit this transporter.Experimental ApproachWe employed a computational approach, by which 538 approved and investigational drugs were docked into an ensemble of SLC19A3 cryo-EM structures, followed by experimental binding studies, transport inhibition assays, and structural validation.Key ResultsEight novel compounds were identified that bind and inhibit SLC19A3. To visualise such a new drug interaction, we determined the cryo-EM structure of SLC19A3 bound to domperidone, a dopamine D2 receptor antagonist used for the treatment of nausea and gastrointestinal disorders. Our computational work together with biochemical and cellular transport assays expands the understanding of SLC19A3-drug interactions, highlights the power of virtual screening approaches using structural ensembles, and provides a three-dimensional pharmacophore model for SLC19A3 inhibitors.Conclusion and ImplicationsThese findings offer a basis for addressing drug-induced thiamine deficiencies and pre approach can be used to optimise pharmacological strategies involving SLC19A3-interacting compounds in the future
A nanobody specific to prefusion glycoprotein B neutralizes HSV-1 and HSV-2
No full textThe nine human herpesviruses, including herpes simplex virus 1 and 2, human cytomegalovirus and Epstein–Barr virus, present a significant burden to global public health1. Their envelopes contain at least ten different glycoproteins, which are necessary for host cell tropism, attachment and entry2. The best conserved among them, glycoprotein B (gB), is essential as it performs membrane fusion by undergoing extensive rearrangements from a prefusion to postfusion conformation. At present, there are no antiviral drugs targeting gB or neutralizing antibodies directed against its prefusion form, because of the difficulty in structurally determining and using this metastable conformation. Here we show the isolation of prefusion-specific nanobodies, one of which exhibits strong neutralizing and cross-species activity. By mutational stabilization we solved the herpes simplex virus 1 gB full-length prefusion structure, which allowed the bound epitope to be determined. Our analyses show the membrane-embedded regions of gB and previously unresolved structural features3,4, including a new fusion loop arrangement, providing insights into the initial conformational changes required for membrane fusion. Binding an epitope spanning three domains, proximal only in the prefusion state, the nanobody keeps wild-type HSV-2 gB in this conformation and enabled its native prefusion structure to be determined. This also indicates the mode of neutralization and an attractive avenue for antiviral interventions
Interfacial boron segregation in a high-Mn and high-Al multiphase lightweight steel
No full textInterface segregation affects the microstructure evolution and mechanical properties of alloys, including strength, ductility and damage tolerance. This is particularly true for multiphase high-strength steels containing multiple types of interfaces whose characteristics are key factors influencing the steels’ mechanical performance. The different tendencies of solute segregation to different types of interfaces can lead to complex segregation behavior, which needs to be understood. Here, we focus on the segregation behavior of B in a high-Mn, high-Al lightweight steel with a two-phase austenite-ferrite microstructure. We find distinct B segregation at both austenite and ferrite grain boundaries as well as at austenite-ferrite phase boundaries after high temperature annealing (1100°C) and fast quenching. The segregation process is governed by local equilibrium between bulk and interfaces as discussed in terms of thermodynamic and ab initio calculations. Our findings reveal a dependence of B segregation on the interface structure regardless of the adjacent phases, which can be explained in terms of respective interfacial energy in accord with the Gibbs adsorption isotherm. In addition, co-segregation of B and C is observed at both high-angle and low-angle ferrite grain boundaries due to the attractive interaction between the two solutes in the bulk ferrite phase. In contrast, for austenite grain boundaries, C depletion is observed owing to its site competition effect and repulsive interaction with B in austenite. These observations help to guide interface segregation engineering in complex multiphase lightweight steels to improve their mechanical performance
Tailoring the active sites in Cu-SSZ-13 as a catalyst for the selective catalytic reduction of NH to minimize HCHO and HCN emissions
No full textSynthetic fuels are promising candidates for achieving carbon neutrality and lowering soot formation. However, their combustion leads to notable amounts of formaldehyde and other oxygenates. These emissions further affect the selective catalytic reduction (SCR) of NOx and cause secondary HCN emissions due to their reaction with NH3. This study focuses on elucidating the structural features of Cu-SSZ-13—a widely applied NH-SCR catalyst—that lead to high formaldehyde conversion while minimizing HCN emissions. Complementary in situ/operando characterization techniques supported by density functional theory calculations are systematically applied for a series of Cu-SSZ-13 catalysts with different Cu loadings and Si/Al ratios. The obtained results demonstrate that the decrease in SCR activity due to the presence of HCHO correlates with the formation of mobile Cu–CN species, whereas low HCN emissions at >350 °C are associated with the presence of ZCuOH species in the catalyst structure
Neutrino-Mass-Driven Instabilities as the Earliest Flavor Conversion in Supernovae
No full textCollective neutrino flavor conversions in core-collapse supernovae begin with instabilities, initially triggered when the dominant νe outflow concurs with a small antineutrino flux of opposite lepton number, with ν¯e dominating over ν¯μ. When these “flipped” neutrinos emerge in the energy-integrated angular distribution (angular crossing), they initiate a fast instability. However, before such conditions arise, spectral crossings typically appear within 20 ms of collapse, i.e., local spectral excesses of ν¯e over ν¯μ along some direction. Therefore, postprocessing supernova simulations cannot consistently capture later fast instabilities because the early slow ones have already altered the conditions