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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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System identification of oscillating surge wave energy converter using physics-informed neural network
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A modern look at the oscillation physics case for a neutrino factory
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Control co-design and optimization of oscillating-surge wave energy converter
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Quantum control of an oscillator with a Kerr-cat qubit
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Correlated spin-wave generation and domain-wall oscillation in a topologically textured magnetic film
Spin waves, or magnons, are essential for next-generation energy-efficient spintronics and magnonics. Yet, visualizing spin-wave dynamics at nanoscale and microwave frequencies remains a formidable challenge due to the lack of spin-sensitive, time-resolved microscopy. Here, in this study, we report a breakthrough in imaging dipole-exchange spin waves in a ferromagnetic film owing to the development of laser-free ultrafast Lorentz electron microscopy, which is equipped with a microwave-mediated electron pulser for high spatiotemporal resolution. Using topological spin textures, we captured the emission, propagation, reflection and interference of spin waves from spin anti-vortices under radio-frequency excitations. Remarkably, we show that spin-wave generation is closely tied to the oscillatory motion of specific magnetic domain walls, providing the missing link between wave emission and wall dynamics near magnetic singularities. This work opens new possibilities in magnonics, offering a nanoscopic view of spin dynamics via transmission electron microscopy and enabling controlled excitation via radio-frequency fields for exploring non-equilibrium states in magnetic and multiferroic systems.
Missing components in ΛCDM from DESI Y1 baryonic acoustic oscillation measurements: Insights from redshift remapping
We explore transformations of the Friedman-Lemaître-Robertson-Walker (FLRW) metric and cosmological parameters that align with observational data while aiming to gain insights into potential extensions of standard cosmological models. We modified the FLRW metric by introducing a scaling factor, e 2Θ(a) –the cosmological scaling function (CSF), which alters the standard relationship between cosmological redshift and the cosmic scale factor without affecting angular measurements or cosmic microwave background (CMB) anisotropies. Using data from DESI Year 1, Pantheon+ supernovae, and the Planck CMB temperature power spectrum, we constrained both the CSF and cosmological parameters through a Markov chain Monte Carlo approach. Our results indicate that the CSF model fits observational data with a lower Hubble constant (although it is compatible with the value given by Planck 2018 within 1σ) and is predominantly dark matter dominated. Additionally, the CSF model produces temperature and lensing power spectra similar to those predicted by the standard model, though with lower values in the CSF model at large scales. We also checked that when fitting a CSF model without dark energy to the data, we obtain a more negative conformal function. This suggests that the CSF model may offer hints about missing elements and opens up a new avenue for exploring physical interpretations of cosmic acceleration.
Anticathode effect on multimodal azimuthal oscillations in electron beam generated E×B plasma
Electron beam (e-beam) generated plasmas with applied crossed electric and magnetic (E x B) fields are promising for low-damage (gentle) material processing. However, these plasmas can be subject to the formation of plasma non-uniformities propagating in the E x B direction. These rotating plasma structures (or “spokes”) enhance the transport of charged species across the magnetic field, which can harm the gentle processing capability of the plasma. In this work, we investigate the role of electrostatically active boundaries on the spoke formation by incorporating a variable bias conducting boundary (known as an anticathode) placed on the axially opposite side of the cathode. Our findings indicate azimuthal mode suppression occurs when the anticathode is electron collecting. Furthermore, we show selective azimuthal mode suppression by biasing the anticathode to an intermediate potential between the cathode and anode potentials. In conclusion, these findings suggest a link between the axial electron confinement in the e-beam generated plasma and azimuthally propagating plasma structure formation.
Multimodal azimuthal oscillations in electron beam generated E×B plasma
Electron beam (e-beam) generated plasmas with applied crossed electric and magnetic (E×B) fields are promising for low-damage material processing. However, these plasmas can be subject to the formation of azimuthally propagating structures that enhance the radial transport of energetic charged species, which can harm the gentle processing capability of the plasma. In this work, we investigate the azimuthal structure formation in an e-beam generated E×B plasma using experimental diagnostics and 2D3V particle-in-cell simulations. Our findings demonstrate the formation of multiple simultaneously occurring azimuthally propagating modes that exhibit nontrivial radial dependence. It is suggested that the multimodal azimuthal spectrum is caused in part by the radial outflow of ions in the plasma.
Co-designing Spectral Transformation Oracles with Hybrid Oscillator-Qubit Quantum Processors: From Algorithms to Compilation
We co-design a family of quantum eigenvalue transformation oracles that can be efficiently implemented on hybrid discrete- or continuous-variable (qubit or qumode) hardware. To illustrate the oracle’s representation-theoretic power and near-term experimental accessibility, we encode a Gaussian imaginary time-evolution spectral filter. As a result, we define a continuous linear combination of unitaries block encoding. Due to the ancillary qumode’s infinite-dimensional nature, continuous-variable qumodes constitute a powerful compilation tool for encoding continuous spectral functions without discretization errors while minimizing resource requirements. We then focus on the ubiquitous task of preparing eigenstates in quantum spin models. For completeness, we provide an end-to-end compilation which expresses high-level oracles in terms of an experimentally realizable instruction set architecture in both 1D and 2D. Finally, we examine the leading-order effects of physical errors and highlight open research directions. Our algorithms scale linearly with the spatial extent of the target system and are applicable to both near-term and large-scale quantum processors.
Ab initio study of quantum oscillations in altermagnetic and nonmagnetic phases of RuO 2
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Persistent oscillation of a Cooper-pair condensate of topological defects in a nonintegrable quantum Ising chain
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Search for very-short-baseline oscillations of reactor antineutrinos with the SoLid detector
In this paper we report the first scientific result based on antineutrinos emitted from the BR2 reactor at SCK CEN. The SoLid experiment uses a novel type of highly granular detector whose basic detection unit combines two scintillators, polyvinyl toluene (PVT) and Li 6 F : ZnS ( Ag ) , to measure antineutrinos via their inverse- β -decay products. An advantage of PVT is its highly linear response as a function of deposited particle energy. The full-scale detector comprises 12 800 voxels and operates over a very short 6.3–8.9 m baseline from the reactor core. The detector segmentation and its three-dimensional imaging capabilities facilitate the extraction of the positron energy from the rest of the visible energy, allowing the latter to be utilized for signal-background discrimination. We present a result obtained from 280 reactor-on days (55 MW mean power) and 172 reactor-off days, respectively, of live data taking. A total of 29 479 ± 603 (stat) antineutrino candidates have been selected, corresponding to an average rate of 105 events per day and a signal-to-background ratio of 0.27. A search for disappearance of antineutrinos to a sterile state has been conducted using complementary model-dependent frequentist and Bayesian fits, providing constraints on the allowed region of the reactor antineutrino anomaly.
Anisotropic Thermal Conductivity Oscillations in Relation to the Putative Kitaev Spin Liquid Phase of α-RuCl 3
In the presence of an external magnetic field, the Kitaev model could host either gapped topological anyons or gapless Majorana fermions. In α-RuCl 3 , the gapped and gapless cases are only separated by a 30° rotation of the in-plane magnetic field vector. The presence or absence of the spectral gap is key for understanding the thermal transport behavior in α-RuCl 3 . Here, we study the anisotropy of the oscillatory features of thermal conductivity in α-RuCl 3 . We examine the oscillatory features of thermal conductivities (κ / / a, κ / / b) with fixed external fields and find distinct behavior for the gapped (B / / a) and gapless (B / / b) scenarios. Furthermore, we track the evolution of thermal resistivity (λ α ) and its oscillatory features with the rotation of in-plane magnetic fields from B / / b to B / / a. The thermal resistivity λ(B, φ) displays distinct rotational symmetries before and after the emergence of the field-induced Kitaev spin liquid phase. These results suggest that oscillatory features of thermal conductivity in α-RuCl 3 are closely linked to the putative Kitaev spin liquid phase and its excitations.
Initial value formulation of a quantum damped harmonic oscillator
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