Accelerator Physics
Effect of transition layer on wakefield in plasma waveguide
Peter Markov, Kostyantyn Galaydych and Gennadiy Sotnikov
Using 2.5D particle-in-
cell simulations, we investigate the parameters of a
plasma wakefield accelerator (PWFA) for positrons and electrons in a layered
plasma waveguide (LPW) in the presence of a transition layer (TL) between two layers of uniform
plasma with different densities. The layered
plasma is modeled as a combination of a near-wall tubular
plasma of higher density and an on-axis
plasma column of substantially lower density, separated by a TL in which the
plasma density varies smoothly from the lower to the higher value according to a specified law. It is shown that using the PWFA parameters determined for a layered
plasma waveguide without the transition layer changes the acceleration conditions when the TL is present, and that this change depends on the TL thickness. It is demonstrated that when the TL thickness exceeds the skin-layer depth in the tubular
plasma, the positron acceleration rate decreases substantially. The methods are proposed for correcting the parameters of the
plasma waveguide under consideration that compensate for the decrease in the energy gain of the accelerated bunches and ensure their stable transport.
Read the full abstract ▾
Materials Science
The phonomagnet: Spontaneous order of phonon angular momentum
Maike Fahrensohn and R. Matthias Geilhufe
Magnetism is a fundamental property of matter, typically arising from collective ordering of electronic
spin and orbital angular momentum. Other quasiparticles interact with magnetism. However, they have not been considered its primary source. Here we show that
phonons can generate a distinct form of magnetism through spontaneous ordering of their angular momentum. This phonomagnetism emerges from
spin-
phonon angular-momentum coupling, producing an effective exchange interaction between local ionic angular momenta. We show that the interaction strength depends on
spin susceptibility, with a phonomagnetic phase predicted near a
ferromagnetic critical point. Our theory also reveals phononic analogues of established
spin models, including
phonon Heisenberg,
phonon $\Gamma$-model, and
phonon Dzyaloshinskii-Moriya interactions. Combining first-principles
phonon calculations with recent data from Raman spectroscopy, we identify VI$_3$ as a candidate phonomagnet, providing a microscopic framework for interpreting the weak
magnetic anomaly reported above its bulk
ferromagnetic transition. These findings open avenues for new platforms for information storage and manipulation on picosecond timescales.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Time-domain analysis of scalar perturbations of Kerr–Newman black holes with Chern–Simons and Maxwell couplings
Yan-Ming Chen, Hyat Huang, Meng-Yun Lai et al. (+3 more)
To study the onset of scalarization, we investigate linear scalar perturbations around Kerr–Newman black holes in the Einstein-Chern-Simons-Maxwell-scalar theory with quadratic Chern–Simons (CS) coupling $\gamma$ ($\hat\gamma=\gamma/M^2$) and Maxwell coupling $\eta$. For this purpose, we employ hyperboloidal Rácz–Tóth
evolution and a stationary axisymmetric zero-mode computation. The resulting thresholds are compared with the time-domain response at representative points. For $\hat\gamma=0$, we find two asymmetric threshold branches in $\eta$, while for $\hat\gamma=\eta$, the two branches have opposite signs and unequal magnitudes. For unequal CS and Maxwell couplings, the two real threshold branches merge as the
spin or CS coupling increases.
Read the full abstract ▾
All authors Yan-Ming Chen, Hyat Huang, Meng-Yun Lai, De-Cheng Zou, Yun Soo Myung, Ming Zhang
Chemical Physics
Spinorial Weyl Operator Reduction of Dirac (SWORD): Exact Relativistic Quantum Chemistry with Half the Spinor
Jacopo Masotti, Quentin Pitteloud and Luca Frediani
We present an exact self-consistent two-component reformulation of the Dirac equation in the Weyl representation. By exploiting the diagonal structure of the kinetic operator and the purely scalar mass coupling in the Weyl basis, the four-component Dirac problem is reduced to an exact two-component form without introducing inverse-potential operators that arise in conventional energy-decoupling approaches. The resulting second-order differential equations are cast into an integral formulation and solved iteratively via convolution with the Helmholtz Green's function. We implement this formalism within an adaptive multiwavelet basis framework, providing rigorous, user-defined error control. Proof-of-concept calculations for simple atomic systems demonstrate the numerical stability, accuracy, and efficiency of the proposed
algorithm.
Read the full abstract ▾
Optics
DOMINIK SCHOCK, ANNA INVERNICI, MICHAEL JAIDL et al. (+5 more)
Optical frequency combs with fast tunability are essential for integrated spectroscopy and sensing. However, achieving such functionality in the terahertz regime presents a significant challenge. This work introduces a novel approach that exploits supermode
symmetry control in terahertz
lasers. By electrically manipulating the gain ratio between coupled concentric ring
lasers, we selectively excite symmetric and antisymmetric supermodes, allowing frequency tuning and spectral modulation across different frequency regimes and operation modes. Moreover, simultaneous lasing of both supermodes results in a reduced total integrated dispersion, widening the comb locking range. Supported by
matrix formalism and numerical simulations, this work demonstrates the potential of
symmetry control for enhanced electro-optic modulation, opening new avenues for on-chip spectroscopy and sensing applications.
Read the full abstract ▾
All authors DOMINIK SCHOCK, ANNA INVERNICI, MICHAEL JAIDL, MIRIAM GIPARAKIS, SASCHA PREU, AARON M. ANDREWS, JURAJ DARMO, KARL UNTERRAINER
High Energy Physics (Theory)
Nonlocal Dirac theory in curved spacetime and the Bunch–Davies vacuum
Paulo José Porfírio and Ramires Nascimento da Silva
We formulate a nonlocal
spin-$1/2$ field theory in curved spacetime in which the form factor is a nonpolynomial entire function of the covariant Dirac operator. We derive the corresponding nonlocal Dirac equation and analyze its coupling to
gravity and to a $\rm U(1)$ gauge field. As an application, we study the theory in the open chart of de Sitter spacetime and construct the associated nonlocal Bunch–Davies modes. The nonlocal dynamics can be mapped, branch by branch, onto the local Dirac equation with an effective mass $M_n$. For the exponential form factors considered here, the effective masses are expressed in terms of branches of the Lambert-$W$ function. We show that the Euclidean analyticity structure of the Bunch–Davies construction is preserved. On the physical positive-residue branch, the Bogoliubov coefficients, squeezing parameter, occupation number, and
entanglement entropy acquire explicit nonlocal corrections, while the absence of physical fermionic supercurvature modes is preserved. The local theory is smoothly recovered in the limit $\Lambda\to\infty$.
Read the full abstract ▾
Quantum Physics
Value of spatially multiplexed SNSPDs with photon-number-resolving capabilities
Fabio Auriemma and Mikkel Ejrnaes
We develop a combinatorial and
Bayesian framework to quantify the information gained by increasing the local
photon-number resolution of multiplexed detection systems based on superconducting nanowire single-
photon detectors (SNSPDs). Motivated by recent studies that attribute
photon-number resolving capabilities to a single SNSPD overcoming the typical on/off detection mechanism, we generalize the existing formulation for the binary devices by deriving the probability response tensor of multiplexed systems based on SNSPDs with an arbitrary number of resolvable states. We include finite efficiency through binomial loss convolution and, separately, assess the impact of dark counts. From this response tensor we derive a generalized N-
photon detector fidelity, a
Bayesian photon-number reconstruction, and the corresponding reconstruction fidelity. We particularize this formulation to study 2-, 3- and 4-state multiplexed systems with different numbers of detectors and show that increasing local
photon-number resolution systematically improves both detector fidelity and
Bayesian photon-number reconstruction. This substantially relaxes the quadratic scaling between detector number and resolvable
photon-number required by purely binary multiplexed arrays. These results provide a quantitative value-of-information assessment for multi-state
photon-number-resolving detector arrays.
Read the full abstract ▾
High Energy Physics (Experiment)
FPGA-based muon shower identification and graph neural network tracking algorithms for HL-LHC triggers
Daniel Estrada, Elena Aller, Andrea Cardini et al. (+3 more)
This work presents two hardware-accelerated strategies for the upgrade of the CMS Level-1 Trigger (L1T) to target efficiency losses due to highly energetic radiating
muons and unconventional physics signatures, such as Long-Lived Particles (LLPs). Operating directly on low-level detector hits, the first strategy implements a dedicated
muon shower identification
algorithm in the CMS barrel region that monitors hit multiplicities in the Drift Tube chambers to generate Shower Primitives. Executing with sub-bunch-crossing latency and ultra-low resource consumption, this
algorithm successfully tags showered
muons and provides essential context for downstream track finders. The second approach targets the barrel-endcap transition (overlap) region by evaluating Graph Neural Networks to reconstruct displaced
muon tracks. Following a divided methodology that first isolates hardware feasibility from evolving physics refinements, an initial proxy model based on a GraphSAGE architecture is evaluated to validate its viability on FPGAs within strict latency limits. This implementation utilizes an INT8-PO2 quantization technique coupled with a data-driven bit-width optimization. By replacing DSP-heavy fixed-point multiplications with fast compile-time arithmetic bit-shifts and allocating the minimum required bits per signal, this hardware-software co-design reduces DSP utilization to $20\%$ and achieves a deterministic inference latency of just $19$ clock cycles. Together, these developments pave the way for triggering on non-standard
muon signatures, such as those from LLP decays, at L1T.
Read the full abstract ▾
All authors Daniel Estrada, Elena Aller, Andrea Cardini, Santiago Folgueras, Pelayo Leguina, Javier Prado
Disordered Systems and Neural Networks
Disorder-driven loss of crystalline coherence in two-dimensional electron solids: Quantum Hartree-Fock and classical molecular dynamics
Sankar Das Sarma and Haining Pan
We investigate the effects of quenched disorder on two-dimensional electron solids using Hartree-Fock theory and classical molecular dynamics. Increasing disorder weakens crystalline correlations, broadens the structure factor, and reduces the measured coherence length toward the pristine
lattice spacing. This
evolution is consistent with the Imry-Ma and Larkin picture: random pinning disrupts translational order on sufficiently long scales, and stronger disorder reduces the distance over which crystalline organization survives. Classical simulations further show that stronger pinning raises the temperature for particle rearrangement even after crystalline order has disappeared. Disorder thus suppresses structural coherence while stabilizing an amorphous solid against thermal rearrangement.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Scalaron Quasinormal and Quasi-Bound Modes of Schwarzschild Black Holes in the Bondi-Sachs Formulation of Metric $f(R)$ Gravity
Bishop Mongwane, Didam G. A. Duniya, Seturumane Tema et al. (+2 more)
We study scalaron quasinormal modes and quasi-bound states of Schwarzschild black holes directly within the Bondi-Sachs formulation of metric $f(R)$
gravity, combining frequency-domain analyses with characteristic time
evolution. Starting from the linearised characteristic equations, we obtain the massive scalar master equation and show that the tensor master equation takes the same form as in general relativity. For the analytic models considered here, the linear scalar spectra depend on the $f(R)$ theory only through the dimensionless combination $\mu M$. We compute both quasinormal and quasi-bound spectral branches using Leaver's continued-fraction method and compare them with independent literature
benchmarks. To complement the frequency domain analysis, we evolve the scalaron perturbation equations using a fourth order convergent characteristic scheme. Applying
matrix-pencil stability scans to the resulting waveforms, we independently recover fundamental quasinormal frequencies consistent with the continued-fraction results within the measured extraction-stability scales. Finally, for a selected finite-mass case, we demonstrate the extraction of both oscillation frequencies and damping rates of the fundamental quasinormal mode and quasi-bound state from separate time windows of the same waveform at one extraction radius, without imposing either spectral branch at the finite outer boundary.
Read the full abstract ▾
All authors Bishop Mongwane, Didam G. A. Duniya, Seturumane Tema, Sanele Ziqubu, David F. Mota
Mathematical Physics
Quantum Fluctuations in Bose–Einstein Condensates:Microscopic Correlations and Moment Bounds
Mauris Chueng, Keheng Zhu and Hexiang Wang
We study higher moments of
quantum fluctuations and microscopic correlation energy in the three-dimensional Gross–Pitaevskii regime. For a smooth, compactly supported, nonnegative radial interaction and an $N$-independent normalized initial condensate wave function in $H^6$, we propagate the third spectral moment of a positive correlated energy along the exact many-body
evolution. A uniform initial bound controls the third moment of the depletion number and sixth moments of collective one-particle fluctuations on every compact time interval, independently of $N$. For a nonzero interaction and a smooth, compactly supported initial condensate, we also identify the excitation-energy measure at scale $N^2$, weighted by the first energy. This limit holds for norm-convergent pure-state families with a uniform bound on the initial third correlated-energy moment. Its positive-energy part is a spectral measure of the relative scattering operator $-2\Delta+v$, multiplied by a time-dependent dressed contact. We compute the radial density and prove strict positivity of the contact for nonzero references with finite kinetic energy and finite mean excitation number. The same evolving states have bounded physical fluctuation moments and excitation-energy moments of order $p>1$ bounded below by a positive multiple of $N^{2p-2}$, in the extended spectral sense. Inverse powers of the positive initial energy construct admissible pure and mixed families. For the norm-convergent pure-state class, we determine the scaled interaction-energy moments for $1\le p<2$ and bound the second moment by $O(N^2)$. A finite cubic approximation has norm error $O(N^{-3/16})$ on the energy form domain and $O(N^{-5/4})$ on a stronger initial domain of its generator.
Read the full abstract ▾
Quantum Physics
Adaptive complete quantum search with unknown number of solutions
Raj Alexandru Guţoiu, Bogdan-Călin Ciobanu and Pantelimon George Popescu
Unstructured database search is a fundamental problem that requires finding one or more elements satisfying a specific property within a set of candidates. While Grover's
algorithm provides a quadratic speedup for finding a marked element when the number of solutions is known, finding all solutions when their number is unknown presents additional challenges. In this paper, we thoroughly analyze this problem by considering all the different regimes of combinations of classical, Grover and generalized fixed-point
quantum search instances. We unify these into an adaptive
Bayesian approach that maximizes the expected success probability per unit execution time at each searching instance. For a problem with a known number of solutions, much lower than the database size, we prove that our proposed approach is asymptotically optimal within the considered search model. Furthermore, we prove that for any probability distribution characterizing the likely number of solutions, in regimes where the classical verification time is at most 25% of the
quantum amplitude amplification time, hybrid classical and Grover approaches are preferred to generalized fixed-point. Outside of this regime, we derive an upper bound on the maximal improvement achievable by fixed-point search compared to the best Grover-based score. Additionally, we determine the optimal transition point between classical sampling and
quantum searching using an integral approximation of the probability distribution of the number of solutions. The analytical results are also supported by numerical simulations of the proposed
algorithm and by comparisons between the generalized fixed-point and Grover-based search policies.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Direct Observation of Nanoscale Polarization Switching in HZO Ferroelectrics Using STEM-EBIC
Prasanna Venkatesan, Yueyun Chen, Tristan P. O'Neill et al. (+16 more)
We report the experimental observation of discrete ferroelectric switching down to 0.475 nm x 0.475 nm in HfO2-based ferroelectrics using correlated STEM electron beam induced current (EBIC) imaging and nanoscale voltage pulsing. These high-resolution measurements reveal single-domain switching events characterized by abrupt, bi-state transitions with no intermediate polarization states. By mapping polarization-voltage behavior and switching kinetics across thousands of domains, we extract spatially resolved switching thresholds (Emin), switching speeds (tsw), and remanent polarization (2Pr), uncovering robust scaling trends. Larger domains exhibit nearly twice the polarization and faster switching despite higher Emin, while smaller domains switch more slowly at the same field. Sub-domain imaging enables quantification of variation scaling: polarization variation increases linearly logarithmically with area, with inter-domain variation dominating intra-domain variation. Importantly, we show that multi-bit operation arises from the statistical distribution of domain-level switching, rather than partial polarization, enabling distinct and reliable states in devices as small as 0.01 um2. These findings provide a foundational experimental framework for designing scalable, multi-bit ferroelectric
memory based on grain- and domain-level heterogeneity.
Read the full abstract ▾
All authors Prasanna Venkatesan, Yueyun Chen, Tristan P. O'Neill, Ho Leung Chan, Hari Jayasankar, Priyankka Ravikumar, Zekai Wang, Shelby S. Fields, Megan K. Lenox, William A. Hubbard, Andrea Padovani, Luca Larcher, Gaurav Thareja, Shimeng Yu, Jon F. Ihlefeld, Wanki Kim, Daewon Ha, Brian C. Regan, Asif Khan
Quantum Physics
Quantum Leakage from Shamir Sharing with Correlated Resources
Isaac Barouch Essayag and Aryeh Lev Zabokritskiy
We study leakage from Shamir secret sharing when each device uses its share to produce one
qubit from an initial
quantum resource independent of the secret and sharing randomness. We prove exponentially small trace distance between the leakage states of any two secrets, when reconstruction requires a sufficiently large fraction of the shares, for fixed stationary chains satisfying an upper operator mixing condition and for resources generated by fixed finite
quantum memories with primitive transfer channels. These guarantees permit arbitrary extensions of the device marginal as adversary side information and hold uniformly over
prime fields larger than the number of shares. For independent device–reference pairs, which provide the quantitative input to the argument, we determine the optimal exponential base when reconstruction requires all shares: $2\sqrt2/\pi$ for a
qubit and $2/\pi$ for a classical bit, in both cases allowing arbitrary finite references. A comparison of selected marginals with product states converts the bounds for independent device–reference pairs into security guarantees for the correlated resources.
Read the full abstract ▾
Astrophysics of Galaxies
Tentative Detection of FeS toward Orion SrcI
Aitana Tasa-Chaveli, Holger S. P. Müller, Álvaro Sánchez-Monge et al. (+3 more)
Iron sulfide (FeS) is a key refractory compound in astrophysical environments. It is commonly found in meteorites and evidence of FeS has only been reported in solid form in a protoplanetary environment. Furthermore, FeS is of astrobiological interest since it acts as a precursor to the formation of pyrite (FeS$_2$), which plays a key role in anaerobic metabolism. We present millimeter-wave spectroscopic calculations for gaseous FeS and report its tentative detection toward the massive disk Orion SrcI. If confirmed, this would constitute the first ever detection of gaseous FeS in the interstellar medium. Our data are consistent with a FeS column density of $\sim1.7 \times 10^{15}$ cm$^{-2}$. Comparing to other sulfur reservoirs, the amount of sulfur locked in FeS is more than three orders of magnitude lower than that contained in SO$_2$ and SiS. However, FeS emission may arise from a different region as it is the case for the metallic salt NaCl. Our results support the presence of FeS in interstellar grains and are consistent with grain destruction playing an important role in the origin of the FeS emission. The observations, however, are still insufficient to discern whether FeS is a main sulfur reservoir in molecular clouds or a primary carrier of refractory iron-bearing material.
Read the full abstract ▾
All authors Aitana Tasa-Chaveli, Holger S. P. Müller, Álvaro Sánchez-Monge, Asunción Fuente, Adam Ginsburg, Thomas Möller
Instrumentation and Methods for Astrophysics
Sub 35-ps Single-Photon Stellar Intensity Interferometry of Vega
Verena G. Leopold, Sebastian Karl, Stefan Richter et al. (+7 more)
SII enables measurements of
stellar photospheres by correlating intensity fluctuations, offering a robust alternative to amplitude-based techniques. With the advent of modern single-
photon counting detectors, this method has re-emerged as a powerful technique in
stellar interferometry exploiting their ultra-high timing resolution. We determine the
stellar diameter of Vega at 405 nm using spatial intensity correlations measured at the C2PU facility, part of the Observatoire de la Cote d'Azur. We employed a setup identical to Leopold et al. (2025). The two campaigns in April and August 2024 used hybrid photodetectors (HPDs; 22.7 ps resolution) and new PhotonPix detectors (34.8 ps resolution). A Photonscore TDC integrated
photon arrival times and IRIG-B timestamps for synchronization. Our analysis consisted of calculating auto- and cross-correlation histograms from the recorded data, which were then normalized and corrected for optical path differences. The temporal auto-correlations yield a consistent coherence time of 0.21 ps. This confirms the effectiveness of the PhotonPix detectors despite a slight degradation in timing resolution relative to the HPDs. Combining the data from the two measurement campaigns yields a uniform disk diameter of Vega of 2.97 +/- 0.23 mas. This agrees with the 3.047 mas diameter predicted by the
stellar atmosphere model at our observation wavelength, validating our technique and the new PhotonPix detectors for precision SII at sub-35 ps resolution. The integration of advanced single-
photon detectors like the PhotonPix into existing IACT SII instruments promises substantial enhancements in signal-to-noise ratio and observational capabilities, particularly with CTA LSTs. Although challenges such as night sky background saturation and precise positioning and guiding remain, SII observations at apparent magnitudes up to 7.8 are within reach.
Read the full abstract ▾
All authors Verena G. Leopold, Sebastian Karl, Stefan Richter, Jean-Pierre Rivet, Yury Prokazov, Evgeny Turbin, Gennady Sintotskiy, Iurii Datii, Jason Aufdenberg, Joachim von Zanthier
Earth and Planetary Astrophysics
Shadows cast by precessing annuli as evidence for an inclined planet in HD 139614
Katie L. Milsom, Tim J. Harries, Evan A. Rich et al. (+3 more)
We analyse scattered-light images at multiple epochs of the protoplanetary disc HD139614 taken with GPI and SPHERE instruments. We show that the azimuthal distribution of the surface brightness of the inner bright ring ($13-21$au) varies with time (likely caused by a structure in the inner-disc at $\sim1$au) and constrain the timescale of this variation to be $<11$months. We show that inner arc ($31-44$au) is likely a spiral and tightly wound, measuring a pitch angle of $6.1\pm1.2^\circ$. Additionally, we construct a physical model to explain the broad shadow across $\sim2/3$ of the outer disc and the azimuthally asymmetric bright ring (which has a shadow not aligned with the broad shadow). We model the disc using 1D warp equations with a fast radiative transfer code to produce scattered-light images. We setup the disc as three annuli separated by gaps with an inclined perturbing
planet between the inner two annuli. The
planet causes the inner annuli to tilt and precess independently casting broad shadows across the outer (un-tilted) annulus. These shadows combine to produce a shadow across $\sim2/3$ of the outer disc and an asymmetric bright ring which matches the observations of HD139614. The precession of the annuli is periodic (so the model matches the observations multiple times) with long precession time-scales ($8.4\times10^3$ and $7.2\times10^4$years for the inner and middle annulus respectively) so the shadows are effectively static over accessible observational time-scales.
Read the full abstract ▾
All authors Katie L. Milsom, Tim J. Harries, Evan A. Rich, John D. Monnier, Anna S. E. Laws, Benjamin R. Setterholm
Materials Science · Cross-listed from cs.CL
Agentic schema-guided extraction of materials process knowledge from scientific literature
Sameer Sadruddin and Jennifer D'Souza
Materials literature contains detailed experimental knowledge, but procedures, chemical entities and measurements remain difficult to aggregate because they are reported in heterogeneous forms and depend on process-specific context. We present SciKGExtract, a schema-guided framework that combines large-
language-model extraction with chemical normalization and
agent-based evaluation and refinement before knowledge-graph integration. We evaluate the framework on 176 atomic-layer-deposition papers describing zinc
oxide (ZnO) and indium–gallium–zinc
oxide (IGZO), together with an expert-annotated full-schema subset. PubChem normalization improves exact-match extraction F1 for every tested model. For ZnO, the best F1 increases from 0.591 for direct normalized extraction to 0.805 with agentic refinement, whereas the best IGZO result is 0.344, revealing the greater difficulty of multicomponent supercycle processes. Evaluation against a deeply nested schema containing 65 experimental properties and 155 quantitative measurement nodes further exposes errors in process
segmentation and numerical assignment. These results show that chemical canonicalization and targeted agentic verification provide complementary controls for converting complex materials literature into reusable, machine-actionable experimental knowledge.
Read the full abstract ▾
Strongly Correlated Electrons
Pairing order and condensate fraction across the BCS-BEC crossover in the two-dimensional attractive Hubbard model
Hao Du, Qian Sun, Zhuotao Xie et al. (+1 more)
We report a systematic study of the superconducting ground state in the two-dimensional attractive Hubbard model, employing the numerically exact auxiliary-field
quantum Monte Carlo method. We focus primarily on the pairing order and condensate fraction across the BCS-BEC crossover. Our numerical calculations cover a broad and physically relevant parameter regime, with the interaction strength $U/t=2\sim 12$ (where $t$ is the nearest-neighbor hopping amplitude) and
fermion density $n=0.25\sim 1.0$. We systematically characterize the dependence of the pairing order and condensate fraction on both the interaction strength and
fermion density, and perform finite-size extrapolations to obtain their thermodynamic-limit values. As complementary quantities, we also provide high-precision numerical results for the double occupancy and total energy. Furthermore, we investigate the effects of next-nearest-neighbor hopping on the superconducting properties of the model. Our results offer a comprehensive set of unbiased numerical data for the attractive Hubbard model, establishing quantitative
benchmarks for understanding superconductivity across the BCS-BEC crossover and for validating future theoretical and numerical approaches.
Read the full abstract ▾
All authors Hao Du, Qian Sun, Zhuotao Xie, Yuan-Yao He
Physics Education
Damping by design in a bilateral electromechanical transducer
Angelo Maria Sabatini
In a bilateral electromechanical transducer, energy exchange across the electromechanical interface allows the electrical termination to modify the mechanical response through electromagnetic feedback. The paper develops this idea from a simple
magnetic pendulum, describing the electromechanical coupling through the flux linkage as a function of rotation angle. Torque and back electromotive force then follow from the same coupling function, making the bilateral nature of the energy conversion explicit. A radial-field moving-coil system provides a particularly simple realization in which the coupling becomes independent of angular position and the resulting electromagnetic damping is controlled by the electrical termination. A two-port representation then identifies this damping as an impedance-reflection effect and provides a quantitative criterion for separating the electrical and mechanical time scales. A numerical example compares ideal current drive with critical electrical termination and confirms the reduced second-order description against the full third-order dynamics. The resulting treatment provides a systematic and physically transparent route from familiar undergraduate electromagnetism and oscillator dynamics to electromechanical feedback, bilateral transduction, and the effect of loading in coupled physical systems.
Read the full abstract ▾
Optics
Extraordinary Optical Spin Hall Effect in 2D Exciton Emission in Open Cavities
Kunal Banerjee, Ben Johns, Nitin Yadav et al. (+2 more)
Open cavities are emerging as a promising platform for studying light-matter interactions. A lossy open cavity couples to an atomic monolayer, resulting in
parabolic dispersive emission at room temperature. Here, light-matter interaction is weak, and the dispersion arises from a phenomenon known as dark strong coupling. The bright 2D
exciton rapidly decays through the cavity mode, leaving behind
spin-dark
excitons of the 2D
lattice, thereby undergoing
symmetry breaking. Further, mapping the polarisation dependence in the k-space reveals
spin-orbit interaction in the coupled system. A synthetic
spin-orbit
Hamiltonian is constructed to extract the effective contributions of Rashba- and Dresselhaus-type interactions in the open cavity. The system shows a clear
evolution of the
spin-orbit effect at room temperature. Here, emission is polarisation-sensitive, yielding high degrees of linear and circular polarisation. This is one of the simplest configurations for studying photonic
spin-orbit coupling, in which an atomic monolayer provides Rashba and Dresselhaus coupling constants of 24 eV Å, and ~10^5 eV Å^2, respectively. Therefore, an open cavity platform is promising for polarisation-sensitive measurements and device applications.
Read the full abstract ▾
All authors Kunal Banerjee, Ben Johns, Nitin Yadav, Anil Shaji, Jino George
Quantum Physics
Robust subspace designs and the power of a unique small quantum witness
Simon Apers, Roman Edenhofer, Benjamin Mathieu-Bloise et al. (+1 more)
The concept of subspace designs was introduced by Guruswami and Xing (STOC'13), and explicit constructions were given by Guruswami and Kopparty (FOCS'13). These are families of subspaces that have small intersection with any given subspace of a fixed dimension. We introduce robust subspace designs. Informally, these are a quantitative extension in which we demand that not too many subspaces of the family contain directions that lie close to any given subspace of a fixed dimension. We give a probabilistic construction of such a robust subspace design of
polynomial size, as well as a non-trivial explicit construction of superpolynomial size. Our main application of this new concept is a
quantum space-bounded variant of the Valiant-Vazirani
theorem (Theor.Comput.Sci.'86), which shows that restricting $\mathsf{NP}$-complete problems to instances with at most one accepting witness preserves hardness under randomized reductions. For
quantum witnesses, the analogous quantity is the dimension of an accepting witness subspace. We use our probabilistic construction of robust subspace designs to isolate a unique witness for space-bounded
quantum Merlin-Arthur protocols with perfect completeness and an acceptance gap outside their perfectly accepting subspace. As further applications, we give a randomized reduction of well-conditioned nullity testing to space-bounded
quantum Merlin-Arthur protocols with perfect completeness. Using a similar idea, we find that ordinary subspace designs allow us to recover the classical $\mathsf{C_= L}$ containment of Allender, Beals, and Ogihara (STOC'96) for general nullity testing through a simpler proof.
Read the full abstract ▾
All authors Simon Apers, Roman Edenhofer, Benjamin Mathieu-Bloise, Partha Mukhopadhyay
High Energy Astrophysical Phenomena
Continuous Gravitational Waves from Thermo-Elastic Mountains in Ultraluminous X-ray Pulsars
Hong-Bo Li, Ziming Wang, Lijing Shao et al. (+1 more)
Fast-spinning, nonaxisymmetrically deformed
neutron stars (NSs) are promising targets for continuous gravitational-wave (CGW) searches with current and next-generation ground-based detectors. Ultraluminous X-ray
pulsars (ULXPs), characterized by super-Eddington
accretion and strong
magnetic fields, provide extreme environments in which substantial nonaxisymmetric deformations may develop. In this Letter, we investigate thermo-elastic mountains generated by magnetically induced temperature asymmetries in the accreted crusts of ULXPs. We connect the crustal thermal structure to an
accretion-column model and solve the full anisotropic heat-transport equation, extending previous perturbative treatments into the nonlinear, strongly magnetized regime. We find that the weak-field approximation begins to break down near $B_{\rm ref}\sim10^{13}\,{\rm G}$, beyond which nonlinear anisotropic heat transport significantly modifies the quadrupolar thermal response. The resulting thermal asymmetries generate substantial thermo-elastic mass quadrupoles at higher field strengths. Although the currently known ULXPs are unfavorable CGW targets because of their relatively slow
spins and, in most cases, large distances, our illustrative
spin-
evolution calculations show that a NS can enter the super-Eddington accretor phase with a
spin period of order $20\,{\rm ms}$. Such rapidly rotating
Galactic ULXPs could lie within the projected sensitivities of next-generation detectors such as the Einstein
Telescope and
Cosmic Explorer. These results extend thermal-mountain physics into the strongly magnetized regime relevant to ULXPs and connect super-Eddington
accretion with prospective CGW observations.
Read the full abstract ▾
All authors Hong-Bo Li, Ziming Wang, Lijing Shao, Ren-Xin Xu
Materials Science
First-Principles Investigation of Multimodal Toxic Gas Sensing in Carbon-Tuned hBN-Graphene Alloys: Chemiresistive, Work-Function, and Optical Responses
Tanjuma Shikder Jhumu and Ahmed Zubair
Compact, reliable, and cost-effective gas sensors have become a highly demanding subject for safety management in the medical sector, chemical manufacturing, food quality monitoring, agriculture, and industrial safety. Hazardous gas emissions need to be controlled and monitored with fast-responsive and highly sensitive sensing devices. A first-principles study employing density functional theory (DFT) was used to investigate the adsorption behavior of Cl2, CO, CO2, NO, NO2, and HCN gas molecules with our proposed
alloys, which consisted of hexagonal boron nitride (hBN) and
graphene (Gr). The
alloy consisting of 22% carbon (BNGr-2) was found to be most competent for sensing Cl2, CO, CO2, and HCN with sufficient adsorption energy, charge transfer, and bandgap alteration. However, NO and NO2 gas molecules showed more engagement with 33% carbon-proportioned
alloy (BNGr-3) in terms of adequate gas sensing properties. NOx gases exhibited the most chemiresistive sensitivity towards the adsorbents. Other gases also showed significant chemiresistive sensitivity and distinct selectivity ratios, which would facilitate these
alloys as chemiresistive sensors. Besides, noticeable work function variation (~20%) of these systems manifested potential as work function based sensors. Cl2 and NO2 showed strong physical adsorption, while the rest of the gases were weakly to moderately physisorbed, resulting in very short recovery times (10-1 ~ 10-6 seconds). Additionally, the distinctive absorption spectra observed for the gas analyte systems highlighted the potential of the proposed
alloys as optical gas sensors. Temperature variation revealed that all gas molecules can be freed from the adsorbent BNGr-2 at 425 K. These findings imply hBN-Gr
alloys as promising gas sensors for pollution
auditing.
Read the full abstract ▾
Optics
Electro-Optical Metalens for Near-Surface Cooling of a Levitated Particle
Pedro Rosso Gomez, Bruno Melo, Adeel Afridi et al. (+3 more)
Advanced levitation optomechanics in the
quantum regime requires sophisticated quantumengineered protocols operating at shorter length and time scales, demanding an increasing control over both optical and electrical potentials. Integrated chip-scale platforms offer a natural route toward such control. Here, we demonstrate optical levitation in
vacuum using a miniaturized hybrid electro-optical metalens. Motion control is achieved using a high numerical aperture metalens combined with electrical active feedback using planar electrodes, enabling cooling to low
phonon occupations. Reheating measurements enable us to rule out any significant influence from electric field noise; an encouraging result for the future development of on-chip levitation platforms operating close to surfaces. This compact integrated platform facilitates the precise manipulation and control of levitated nanoparticles while laying the ground toward exploiting the full capacity of metaoptics to engineer complex optical potentials, marking a significant step forward in technologies for
quantum levitation optomechanics.
Read the full abstract ▾
All authors Pedro Rosso Gomez, Bruno Melo, Adeel Afridi, Mohamed Sabry Mohamed, Nadine Meyer, Romain Quidant
Instrumentation and Methods for Astrophysics
Design and development of the PRIMAger instrument for PRIMA
Anne Costille, Fabrice Madec, Johan Floriot et al. (+11 more)
PRIMA (PRobe far-Infrared Mission for Astrophysics) is an infrared space observatory designed to operate over the next decade. Equipped with a 1.8 m
telescope actively cooled to 4.5 K, the project is currently in the concept study phase as part of the NASA Probe Explorers program. PRIMA will carry two instruments: FIRESS and PRIMAger. PRIMAger will offer two observation modes: hyperspectral imaging and polarimetric imaging. Both channels will use ultra-sensitive kinetic inductance detector (KID) arrays, covering wavelengths from mid-infrared to far-infrared. A European consortium will develop the cold unit of the PRIMAger instrument while the Readout Electronics and Continuous Adiabatic Demagnetization Refrigerator (CADR) will be provided by Goddard Space Flight Center (GSFC) and shared between the 2 instruments. The hyperspectral mode will cover the 24-84 $\mu$m range with a spectral resolution of R $\ge$ 8, ensured by a linear variable filter placed in front of the detector. The polarimetric mode will provide polarimetric imaging in four broad bands from 92 to 235 $\mu$m, using KIDs with three polarization orientations. The main structure of the instrument is the optomechanical assembly, cooled at 1K. It supports at first the two focal plane array assemblies incorporating 0.125K detector stages. In addition, the main structure is providing the interfaces for the 0.125K thermal link, the readout cables and the filters. This paper presents the technical requirements and expected performance of the instrument, as well as the associated design of the sub-systems ensuring compliance. A major challenge will be in-flight performance verification. We will also detail the development strategy, including the planned verification and test program.
Read the full abstract ▾
All authors Anne Costille, Fabrice Madec, Johan Floriot, Tony Pamplona, Thomas Prouvé, Laure Ciesla, Marc Sauvage, Willem Jellema, Lorenza Ferrari, Jochem Baselmans, Florent Canourgues, Renaud Goullioud, Carole Tucker, C. Darren Dowell
Astrophysics of Galaxies
Water Abundance and Ortho-Para Ratio in the S140 Photon Dominated Region
Dariusz C. Lis, Sofia Lawsky, Emeric Bron et al. (+2 more)
We analyzed archival far-infrared to submillimeter Herschel PACS, SPIRE, and HIFI spectroscopic observations of the S140
photon dominated region (PDR) to constrain the water vapor abundance and ortho-para ratio in this region. Toward the high-mass protostar IRS1, 52 spectral lines, including 15 water lines, are detected with the PACS and SPIRE instruments. PDR modeling suggests a UV radiation field G0 ~ 1 x 10^3 Habing units, and a thermal gas pressure of 5 x 10^8 K cm^-3 in this region. The models strongly underestimate intensities of high-J CO lines, which may indicate the presence of hot shocked gas associated with
outflows along the line of sight, in addition to the UV irradiated gas. The spectral resolution of the PACS and SPIRE spectrometers is insufficient to separate the PDR and shock contributions. The PDR models further suggest that optically thick ground-state water lines trace primarily surface layers of the PDR. The gas temperature in this region is predicted to be ~ 800 K and the water abundance with respect to hydrogen
nuclei reaches ~ 10^-5. However, the bulk of gas-phase water is located in a more shielded region, deeper inside the PDR, with a gas temperature ~ 24 K, and a gas-phase H_2O abundance of ~ 10^-7. A comparison of the observed water line fluxes toward IRS1 with PDR model predictions shows no evidence for departures from the LTE ortho-para ratio at the local gas temperature, which is assumed in the models. The sensitivity of the Herschel instruments was insufficient to measure the water ortho-para ratio toward the externally illuminated edge-on PDR at the surface of the S140 molecular cloud. Such observations will be possible with the next generation far-infrared spectroscopic space missions currently in development.
Read the full abstract ▾
All authors Dariusz C. Lis, Sofia Lawsky, Emeric Bron, Franck Le Petit, Javier R. Goicoechea
Mathematical Physics · Cross-listed from math.PR
Strong freezing in the binary perceptron model
Shuyang Gong and Shuangping Li
The binary perceptron model studies the set of solutions obtained by intersecting random Gaussian half-spaces with the discrete hypercube {-1,+1}^n. Pioneered in the work by Krauth and Mézard in the 1980s [KM89], one of the most striking physics predictions for this model is strong freezing, which says that typical solutions are isolated. Moreover, the
conjecture was sharpened later to assert that typical solutions are at Hamming distance of order $n$ from every other solution [HWK13],[HK14]. This phenomenon has attracted a lot of
attention over the years, partly due to its intricate connections to statistical physics and computational complexity. We prove that the binary perceptron model exhibits strong freezing with high probability at every fixed positive constraint density and every fixed margin. Our proof is based on the planted model and a restricted partition function that counts solutions having nonnegative overlap with the planted solution. Unlike the full partition function, this restricted one is monotone in the planted direction, so the FKG inequality decouples it from isolation, while the restriction costs only a factor of n+1. Together, these allow us to transfer the isolation of the planted solution to typical solutions, which completes the proof of strong freezing.
Read the full abstract ▾
Quantum Physics
Two-Sided Bounds on Ground State Properties in Lattice Gauge Theories
Eloïc Vallée, Ariel Kelman, Julius Mildenberger et al. (+2 more)
Gauge theories describe fundamental interactions in the standard model of particle physics and build effective theories in condensed matter physics. Being notoriously hard to simulate, these theories are commonly regularized as
lattice gauge theories which can be evaluated with high precision through Monte Carlo
algorithms or variational methods. However, Monte Carlo
algorithms are not applicable in all regimes due to the sign problem; while variational methods,
quantum and classical alike, only give upper-bounds on the ground-state energy. Their precision crucially depends on the chosen ansatz. Here, we present a framework based on a hierarchy of semidefinite programs to yield increasingly good lower-bounds on the ground-state energy and propagate these bounds to extended observables like Wilson loops and mesonic strings. We demonstrate the numerical capabilities by applying the
algorithm to a (1+1)-dimensional $\mathbb{Z}_2$ theory with dynamic fermionic matter and its pure-gauge version in (2+1)-dimensions. In both cases, we obtain certified intervals for the ground-state energy. For a one-dimensional system with 129 sites, the certified interval has a relative spread of $0.04\%$. For a two-dimensional system with 97 sites (corresponding to a $7 \times 8$
lattice), the relative spread is $2.08\%$. Beyond energy estimates, the proposed method provides rigorous bounds on both short- and long-range observables such as Wilson loops over multiple plaquettes and the magnitude of the mesonic string. The method can be both used as a computational microscope into many-body physics and a way to certify results of
quantum simulators.
Read the full abstract ▾
All authors Eloïc Vallée, Ariel Kelman, Julius Mildenberger, Jordi Tura, Patrick Emonts
Quantum Physics
Adiabatic tracking and optimal schedules for classical and quantum Gibbs-state preparation
Pedro C. S. Costa, Mauro E. S. Morales, Dong An et al. (+1 more)
We develop a discrete adiabatic framework for Gibbs-state preparation in classical and
quantum optimisation
algorithms. For finite time-inhomogeneous reversible Markov chains, we derive a tracking
theorem that bounds the distance from the evolving distribution to the instantaneous stationary state by combining two effects: contraction of previously accumulated error by the Markov dynamics and the new error generated as the stationary distribution changes from one step to the next. For Gibbs paths, this leads to explicit step-complexity bounds and to gap- and fluctuation-adapted schedules controlled by the Markov-chain spectral gap and the energy-fluctuation scale $V(\beta)=\sqrt{\operatorname{Var}_{\pi_\beta}(E)}$. In the weak-damping regime, the resulting schedule takes the form $\dot{\beta}\propto\delta(\beta)/V(\beta)$. We then apply the discrete
quantum adiabatic
theorem to temperature-dependent Szegedy
quantum walks. The
quantum-walk eigenphase gap satisfies $\Delta_w=\Theta(\sqrt{\delta})$, where $\delta$ is the spectral gap of the underlying Markov chain. By analysing the finite-difference terms entering the
theorem, we show that this square-root spectral amplification translates into a quadratic improvement in the gap dependence only for suitably gap-adapted schedules. Under the corresponding regularity conditions, the
quantum adiabatic cost scales as $O(\delta_{\min}^{-1/2})$, compared with the classical $O(\delta_{\min}^{-1})$ relaxation scale.
Read the full abstract ▾
All authors Pedro C. S. Costa, Mauro E. S. Morales, Dong An, Kaur Kristjuhan