High Energy Physics (Theory)
On conformal symmetry in large-$N$ quiver mechanics
Andrea De Marco, Mustafa Mullahasanoglu, Joris Raeymaekers et al. (+2 more)
The microscopic description of extremal supersymmetric black holes in AdS$_2$/CFT$_1$ holography has remained elusive despite recent progress in the statistical description of near-extremal black hole physics. In this work we revisit Denef's quiver mechanics description of D-brane bound states in the Coulomb branch, which displays an emergent conformal
symmetry in the AdS$_2$ scaling limit. This conformal
symmetry is however broken by superpotential corrections near the locus where the Coulomb and
Higgs branches meet, and its significance has so far remained unclear. In order to to clarify this issue, we derive and interpret a fixed-point formula for the superconformal quiver index using localization techniques. Focusing on cyclic abelian quivers, we show that, in a certain large-$N$ limit (with the rank $N$ of the quiver gauge group), the fixed points are located in the regime where the conformal description is reliable. In this limit, our expression for the superconformal index precisely captures a contribution to the microscopic scaling BPS index derived by Beaujard, Mondal and Pioline, which was hitherto not visible on the Coulomb branch. Our results are hoped to provide a step towards a stringy realization of AdS$_2$/CFT$_1$ duality.
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All authors Andrea De Marco, Mustafa Mullahasanoglu, Joris Raeymaekers, Paolo Rossi, Gizem Sengör
Solar and Stellar Astrophysics
Polarization geometry of magnetohydrodynamic turbulence
Raphael Skalidis
We introduce a
geometric framework that organizes the second-order statistics of the Elasser fields into polarization states on generalized Poincaré spheres. In this representation, energy, cross-helicity, residual energy, and the phase lag between counter-propagating wave packets emerge as complementary polarization parameters. We derive a Bloch-analogue equation governing the
evolution of polarization states and show that distinct polarization geometries are associated with different cascade dynamics. The framework predicts that transitions in the turbulent spectral scaling coincide with changes in the polarization state of the interacting modes.
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Strongly Correlated Electrons
Field-induced first order transitions and phase coexistence in the Kitaev quantum spin liquid candidate BaCo2(AsO4)2
Tanner J. Legvold, Bin Gao, Rong-Zhu Lin et al. (+9 more)
BaCo2(AsO4)2 (BCAO) is an insulating Kitaev
quantum spin liquid candidate with a rich low-temperature phase diagram. Below 5 K, it exhibits double-zigzag
magnetic order. Upon application of an in-plane
magnetic field, the
magnetic structure first transforms into an up-up-down (UUD) state near 0.12 T and then enters a fully
spin-polarized
ferromagnetic (FM) state near 0.5 T. In the narrow field regime close to the polarized phase, a finite residual thermal conductivity has been reported, suggesting a possible field-induced
quantum spin liquid phase. Using
neutron scattering, we show that the field-induced double-zigzag-to-UUD transition near 0.15 T is accompanied by the emergence of a cluster of localized UUD
spin excitations that coexist with conventional
spin waves. Upon further increasing field, BCAO undergoes a first-order UUD-to-FM transition with coexistence of UUD and FM phases, accompanied by a sharp response in the
spin Seebeck coefficient. These results do not support a
quantum spin liquid scenario near the UUD-to-FM critical field. Instead, modeling indicates that the broad excitations arise from bound
spin-flip pairs, while a low-lying dispersive branch near the FM phase boundary carries the same sign of magnetization as the FM order. These excitations naturally account for the observed sign of the
spin Seebeck response and are likely relevant to the thermal conductivity near the critical field.
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All authors Tanner J. Legvold, Bin Gao, Rong-Zhu Lin, Violet Williams, Tong Chen, Dehong Yu, Chien-Lung Huang, Gage Eichman, Renjie Lui, Benedetta Flebus, Pengcheng Dai, Douglas Natelson
Quantum Physics
Causality from the spectrum: Emergence of causal order from process-matrix mereology
Varun Kushwaha, Nicolas Loizeau, Alexei Grinbaum et al. (+1 more)
In
Hamiltonian systems, the only basis-independent quantity is the spectrum. Given a spectrum,
quantum mereology seeks preferred tensor-product decompositions into local subsystems, leading to the emergence of locality. Causal order, however, remains fixed by the
Hamiltonian time
evolution. In contrast, higher-order
quantum theory permits more general processes that need not possess a definite global causal order. In the process-
matrix framework, specifying a process requires a choice of subsystems corresponding to the input and output
Hilbert spaces of each
agent. A change of basis redefines both the
agents and the corresponding decompositions into subsystems, while leaving the spectrum of the process
matrix invariant. Here, we study how causality arises from this spectrum. First, we derive spectral constraints on processes compatible with definite causal order. Second, we show that, in the thermodynamic limit, generic
quantum processes admit a preferred decomposition with a definite causal order. This suggests a mechanism for the emergence of classical causality only from algebraic ingredients.
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All authors Varun Kushwaha, Nicolas Loizeau, Alexei Grinbaum, Oliver Friedrich
Astrophysics of Galaxies
The Azahar Project: Non-Thermal Physics Drives Star Formation Burstiness and the Evolution of the UV Luminosity Density at Cosmic Dawn
Sergio Martin-Alvarez, Risa H. Wechsler and Debora Sijacki
JWST observations, which have pushed the discovery and characterization of
galaxies to
cosmic dawn, have revealed significant deficiencies in state-of-the-art
galaxy formation simulations, motivating the need for novel, physically grounded models. We present the first results from the Azahar suite of ten high-resolution ($\sim$20 pc), large-volume zoom-in cosmological simulations, which follow the formation of thousands of
galaxies and progressively incorporate radiative transfer (RT),
cosmic rays (CRs), and magnetohydrodynamics in addition to the 'standard' baryonic physics. Our Non-Thermal model, which simultaneously includes RT and CRs on the fly, reproduces the observed UV luminosity function from high
redshifts ($z \sim 14$) to
cosmic noon ($z \sim 3$), as well as the
evolution of the
stellar mass function, the
galaxy main sequence, and observed gas
metallicities. It does so through a combination of burstier
star formation, with enhanced variability on both long ($\gtrsim 50$ Myr) and short ($\lesssim 10$ Myr) timescales, and a transition from high to low
outflow mass-loading factors over
cosmic time as CR pressure builds up in the ISM. We find that simple (boosted) thermal SN feedback models fail to capture the
cosmic evolution of the very first
galaxies because they lack realistic feedback channels that operate on different timescales and have distinct thermodynamical properties, thereby either overproducing
stellar mass or driving overly explosive
outflows. Our results indicate that non-thermal
galaxy formation physics is crucial for providing a robust theoretical framework with which to interpret the high-
redshift galaxy populations now being uncovered by JWST.
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Quantum Physics
Zi-Bo Jin and Yi Zhang
Non-Hermitian systems offer new opportunities for
quantum optimization and computation. Here, we show that non-Hermitian
quantum adiabatic
algorithms require not only a real, gapped spectrum, but also a stable pseudospectrum. We propose a novel framework by mapping non-
unitary quantum circuits to local
Hamiltonian paths, thereby preserving their optimization advantages and shallow depth. While a direct non-Hermitian extension of the Feynman-Kitaev construction suffers severe pseudospectral instability, our history-decoupled construction yields both a controlled pseudospectrum and a real, gapped spectrum. Using the CK
benchmark family of maximum independent set problems, we demonstrate
polynomial-
evolution-time non-Hermitian adiabatic computation that remains robust against perturbations. We further discuss a feasible optical implementation using coupled waveguides with an auxiliary lossy channel. Our work establishes pseudospectral stability, alongside real, gapped spectra, as key principles and a practical route for non-Hermitian
quantum adiabatic computation.
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High Energy Astrophysical Phenomena
Ultraviolet to Infrared Spectroscopy of the Type Ibn SN 2023tsz Suggests a Lower-mass Progenitor
Sergiy S. Vasylyev, Griffin Hosseinzadeh, Luc Dessart et al. (+42 more)
Type Ibn
supernovae are stripped-envelope explosions whose spectra indicate interaction with dense, helium-rich and hydrogen-poor circumstellar material (CSM), making them important probes of late-stage mass loss and progenitor stripping. We present extensive ultraviolet-to-near-infrared spectrophotometry of the Type Ibn SN 2023tsz, including two epochs of HST/STIS ultraviolet (UV) spectroscopy and ground-based optical and near-infrared follow-up observations. The spectra are dominated by intermediate-width emission lines at all phases after maximum light, suggesting that much of the luminosity originates in a cold dense shell (CDS) formed by interaction between the ejecta and CSM. We compare the observations to one-dimensional non-local-thermodynamic-
equilibrium radiative-transfer models of a helium-
star explosion with a mass of $4 M_{\odot}$ at the onset of helium burning. The models reproduce the strong optical and near-infrared He I lines and require an added X-ray irradiation field to match the highly ionized UV features. The spectra are best reproduced by models with an X-ray irradiation power of $L_X \approx 10^8 L_{\odot}$, with the preferred models favoring CDS radii of order $(1.5$–$2) \times 10^{15}$ cm, velocities of $\sim 5 \times 10^7$ cm s$^{-1}$, and interaction powers of a few times $10^{42}$ erg s$^{-1}$. In the optical, the preferred models shift from higher interaction power and smaller radii at early times to lower power and larger radii at later times. These results add to the growing evidence that at least some SNe Ibn arise from lower-mass helium
stars whose final
evolution is shaped by binary interaction.
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All authors Sergiy S. Vasylyev, Griffin Hosseinzadeh, Luc Dessart, Ori Fox, David J. Sand, Alexei V. Filippenko, Qinan Wang, D. Andrew Howell, Jennifer E. Andrews, Moira Andrews, Pallas Beddow, K. Azalee Bostroem, Thomas G. Brink, Peter J. Brown, Asia deGraw, Yize Dong, Joseph Farah, Thomas R. Geballe, Sebastian Gomez, Emily T. Hoang, Brian Hsu, Saurabh W. Jha, Patrick Kelly, Curtis McCully, Darshana Mehta, Megan Newsome, Yuan Q. Ni, Seong Hyun Park, Jeniveve Pearson, Neil Pichay, Justin Pierel, Aravind P. Ravi, Nicolas E. Meza Retamal, Melissa Shahbandeh, Manisha Shrestha, Nathan Smith, Bhagya M. Subrayan, Tamás Szalai, Stefano Valenti, Schuyler D. Van Dyk, Jeonghee Rho, Kathryn Wynn, Yi Yang, Yossef Zenati, WeiKang Zheng
Cosmology and Nongalactic Astrophysics
Forest without Trees is still Fruitful: Constraints on the thermal state of the neutral IGM at $z\approx5.6$ with the 21-cm forest power spectrum
Tomáš Šoltinský, Arnab Chakraborty, Girish Kulkarni et al. (+10 more)
Neutral regions of the intergalactic medium (IGM) during the Epoch of Reionization (EoR) remain largely unexplored due to the limitations of existing probes. Owing to discoveries of numerous high-
redshift radio-bright sources, the 21-cm forest, a series of absorption features imprinted by the neutral IGM in the spectra of such sources, now offers an attractive probe of the thermal and ionization state of the predominantly neutral IGM at $z\gtrsim5.5$. We analyse archival upgraded
Giant Metrewave
Radio Telescope (uGMRT) observations of J352-15, the brightest known
radio-loud
quasar in the EoR ($z=5.82$), to measure the one-dimensional (1D) power spectrum of the 21-cm forest. By comparing the observed power spectrum with forward-modelled synthetic spectra generated from cosmological simulations spanning a wide range of ionization and X-ray pre-heating scenarios, we perform
Bayesian inference even in the absence of a statistical detection. We also present an independent Murchison Widefield Array measurement, although its lower sensitivity prevents competitive constraints. Using uGMRT, we achieve a sensitivity of $3.62\,\rm mJy\,beam^{-1}$ per $6.1\,\rm kHz$ channel. While we do not detect the 21-cm forest statistically, the null detection jointly constrains the mean neutral hydrogen fraction, $\langle x_{\rm HI}\rangle$, and the mean temperature of the neutral IGM, $\langle T_{\rm HI}\rangle$. At the $68\%$ credible level, our analysis disfavours cold and substantially neutral IGM models at $z\approx5.6$, including models with $\langle T_{\rm HI}\rangle \lesssim 27\,\rm K$ for $\langle x_{\rm HI}\rangle=0.1$. These limits probe parameter space allowed by existing Ly$\alpha$ and 21-cm observations, indicating substantial pre-heating of the neutral IGM above the adiabatic cooling floor. This demonstrates that the 21-cm forest has entered the regime of observationally informative statistics.
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All authors Tomáš Šoltinský, Arnab Chakraborty, Girish Kulkarni, Matteo Viel, Cathryn M. Trott, Rashmi Sagar, Nithyanandan Thyagarajan, James S. Bolton, Benedetta Ciardi, Emma V. Ryan-Weber, Soumak Maitra, Abhirup Datta, Nirupam Roy
Astrophysics of Galaxies
How large can galaxies be? Ultra-deep imaging of IC 1101, the most extended known galaxy
Carlos Marrero-de la Rosa, Ignacio Trujillo, Ignacio Ruiz Cejudo et al. (+12 more)
The maximum physical extent that
galaxies can reach is poorly understood. In this regard, IC 1101, one of the most extended and massive
galaxies known, provides a valuable opportunity to constrain the upper limit of
galaxy sizes at the present epoch. Previous deep imaging of the system confirmed its enormous extension, but did not indicate whether it has an edge. We explore this issue using the deepest images ever taken of this
galaxy; ultra-deep g- and r- band imaging from the INT/WFC, reaching {\mu} = 30 mag arcsec^-2 (3{\sigma} in an area equivalent to 10 x 10 arcsec^2). We model and subtract the scattered light from both
stars and the
galaxy itself using an extended PSF characterization and a hybrid wavelet-based deconvolution. Using a combination of surface brightness, colour, and
stellar mass density profiles oriented at different position angles, we find that the main body of IC 1101 extends to Redge = 260 kpc along the semi-major axis (assuming the
redshift of Abell 2029, z = 0.077), enclosing 3.4 x 10^12 M_sun in
stars. This Redge is among the largest edge radii measured for any
galaxy to date, placing IC 1101 at the extreme upper end of the mass-size relation. In addition, we report a large number of asymmetrical, very low surface brightness features around the
galaxy that are spatially consistent with the large-scale disturbances observed in the intracluster medium through X-ray studies of the Abell 2029 cluster, in which IC 1101 is embedded. With a confirmed diameter of around 520 kpc, IC 1101 stands as the largest
galaxy known to date; yet, its outskirts show clear signatures of ongoing mass assembly, indicating that its spatial extent is still growing.
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All authors Carlos Marrero-de la Rosa, Ignacio Trujillo, Ignacio Ruiz Cejudo, Mireia Montes, Fernando Buitrago, Giulia Golini, Sergio Guerra Arencibia, Andrés Asensio Ramos, Raúl Infante-Sainz, Adriana de Lorenzo-Cáceres, Jairo Méndez-Abreu, Samane Raji, Javier Román, Manuel Sánchez-Benavente, Zahra Sharbaf
Astrophysics of Galaxies
Tighter Dark Matter Constraints from the Projected Mass Method: A Neural Network Enhanced Method for Galaxy Groups and Clusters
Yinbo Huang and David Benisty
Measuring the total mass of the Milky Way and nearby
galaxy groups is difficult because classical dynamical
estimators rely on assumptions about satellite orbital geometry that are rarely satisfied in practice, and because only a handful of satellite
galaxies are typically available as kinematic tracers. We present a new framework that corrects the well-known Projected Mass
Estimator (PME) using a residual neural network trained on thousands of simulated
galaxy groups from the IllustrisTNG cosmological simulation. Separate networks are trained for each satellite sample size, from as few as 5 satellites up to 50, so that the correction automatically accounts for the statistical noise that dominates when only a small number of tracers is available. In tests on simulated
halos, the classical PME systematically overestimates
halo masses by factors of $M_{\rm proj}/M_{\rm true} = 1.30^{+0.72}_{-0.62}$ (using the 2D distance) and $1.46^{+0.97}_{-0.72}$ (using the 3D distance), with RMSE of 0.29 and 0.32 dex respectively. The neural-network correction reduces this to $M_{\rm proj}/M_{\rm true} = 1.02^{+0.30}_{-0.26}$ with an RMSE of 0.13 dex. Applied to the Milky Way, the method yields a total mass of $M_{\rm MW} = 1.144^{+0.399}_{-0.296}\times10^{12}\,M_\odot$, with estimates based on the brightest 5-10 satellites favoring a somewhat lower range of $(0.8-0.95)\times10^{12}\,M_\odot$. The modified PME gives a tighter constraint on the virial masses and the inferred dark matter content of
galaxy groups and clusters.
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High Energy Physics (Phenomenology)
1D Luttinger Modes in Carbon Nanotubes as keV Dark Matter Detector
Xiuyuan Zhang and Hao Chen
We propose metallic carbon nanotubes (CNTs) as a one-dimensional plasmon target for light dark matter (DM) direct detection. Unlike conventional gapless electronic targets, where DM primarily excites electron-hole pairs, the low-energy charge response of a metallic CNT is carried by a collective Luttinger-
liquid mode. We compute the projected sensitivity for DM-electron scattering through heavy and light mediators, using
benchmark thresholds motivated by
quantum-capacitance-detector-like and superconducting-quasiparticle-amplifying-transmon-like readout. For an accumulated nanotube length $L_{\text{CNT}}=10^8{\rm m}$, corresponding to milligram-scale single-wall CNT targets, we find competitive reach in the keV–MeV mass range. In the light-mediator case, the projected sensitivity can probe the cosmologically motivated freeze-in
benchmark at keV masses. We also show that the one-dimensional geometry of aligned CNTs induces sidereal-day modulation, providing a handle for distinguishing a DM signal from approximately time-independent sensor backgrounds. These results establish one-dimensional collective modes as a new target class for sub-MeV DM detection. Existing progress in scalable CNT synthesis and superconducting quasiparticle sensing provides a promising experimental foundation, while realizing the proposed detector will require dedicated development of CNT–
superconductor coupling and plasmon-to-quasiparticle conversion.
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Cosmology and Nongalactic Astrophysics
Searching for Folded Primordial Non-Gaussianity with Galaxy Surveys
Si-Xiang Yang and Oliver H. E. Philcox
Large-scale structure provides a powerful probe of inflationary physics through
primordial non-Gaussianity (PNG): the
galaxy power spectrum depends on local PNG through scale-dependent bias, while the
galaxy bispectrum depends sensitively on both equilateral and orthogonal PNG. In this paper, we study whether
galaxy surveys can also probe folded PNG, whose shape is enhanced near $k_1+k_2-k_3\rightarrow0$. We consider three inflationary models with folded PNG, including excited initial states, imaginary speeds of sound, and dissipative inflation. These models fall into two classes: cutoff-regulated cases in which the folded-enhanced region has a power-law width, and dissipation-regulated cases in which the enhanced region is exponentially narrow. We develop a numerical pipeline for computing the corresponding PNG contributions to the
redshift-space
galaxy power spectrum multipoles and bispectrum monopole within the EFTofLSS. Using Fisher forecasts, we show that most of the constraining power on folded PNG comes from the
galaxy bispectrum. For the cutoff-regulated models, nuisance parameter marginalization causes only a mild loss of information at large folded enhancement, but finite
Fourier-space binning degrades constraints once the folded region becomes narrower than the bin width. For the dissipation-regulated models, the exponentially narrow folded enhancement is hard to resolve and the observable signal instead comes from the broader support of the template, leading to weaker binning dependence but larger overlap with the equilateral template. Our results show that folded PNG is a distinctive and promising target for
galaxy bispectrum analyses, and the detectability depends on the width and morphology of the folded enhancement. The numerical pipeline developed in this work is general and can be used to study a wide class of non-separable
primordial bispectra.
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High Energy Physics (Theory)
The $\alpha$-states of a string worldsheet
Suzanne Bintanja and Elliott Gesteau
The worldsheet description of string amplitudes can be reinterpreted as a baby universe field theory. Under this reinterpretation, we determine the $\alpha$-states of a topological string theory: the Hurwitz worldsheet. We find that their relation to the Hartle–Hawking state encodes foundational results in the asymptotic representation theory of the symmetric group. In the
holographic dual, our results characterize the pseudorandom nature of an ensemble of cluster-decomposing correlators.
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Cosmology and Nongalactic Astrophysics
Shohei Saga and Shuichiro Yokoyama
We show that a regular solution for
primordial tensor fluctuations can arise from the higher-order multipoles of the collisionless
neutrino distribution after
neutrino decoupling. Focusing on the leading case with the
neutrino octupole mode (tensor-octupole mode), we derive the initial conditions for the Einstein-Boltzmann system and calculate angular power spectra for the
cosmic microwave background (CMB) anisotropies. Compared with the standard gravitational-wave mode, the tensor-octupole mode has a weaker large-scale metric response. It therefore gives a suppressed reionization bump and a different oscillation phase in the tensor CMB power spectra, providing a way to separate it from the standard tensor mode.
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Computational Physics
Loss of positive definiteness is a symptom, not the cause, of high-Weissenberg-number breakdown
Yuan Yu, Lanjin Lian and Feiyang Chu
Numerical breakdown at high Weissenberg number is often attributed to loss of symmetric positive definiteness (SPD) of the conformation tensor. That conclusion follows from Maxwell-type models without solvent viscosity. With solvent fraction $\beta>0$, the initial-value problem is locally well posed for arbitrary symmetric stress. We derive the missing quantitative theory for indefinite states and test its computational consequences. Frozen-coefficient analysis gives a growth rate uniformly bounded in wavenumber and the direction-resolved instability threshold $\lambda_{\min}(A)<-\beta/(1-\beta)$; stress
diffusion supplies a closed-form cutoff, while the classical $\sigma\propto k$ catastrophe is recovered as solvent viscosity vanishes. A determinant identity shows that violations self-heal on the timescale $\lambda/2$, so persistent violations measure the truncation error that recreates them. Spectral and
lattice Boltzmann tests reproduce the threshold, solvent-fraction reversal, and resolution independence. In four-roll-mill interventions, enforcing SPD delays blow-up by 15 convective times but reduces the stagnation-point Weissenberg number by 30%. Across five coupling schemes, a local second-moment stress source remains stable through the full budget at $\mathrm{Wi}=50$ while carrying $\det A\approx-8.5\times10^5$; the divergence-coupled variant fails at $t^*=47$. The surviving scheme matches published
benchmarks within 0.05% and 0.18% at $\mathrm{Wi}=10$ and 20. Thus loss of positive definiteness is neither necessary nor sufficient for breakdown: the discrete coupling route decides, and the violation is a resolution gauge for which we provide run-time monitors.
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Mesoscale and Nanoscale Physics
Nanoscale stray fields from micromagnets for optimal spin qubit architecture
Sandrine Lopes, Quentin Schaeverbeke, Matthieu M. Desjardins et al. (+3 more)
On-chip micromagnets generate local
magnetic-field asymmetries, enabling electrical control of
spin qubits via electric dipole
spin resonance and their integration into
circuit quantum electrodynamics (QED) architectures. Accurate prediction of
spin-
qubit performance requires modeling micromagnet stray fields beyond the saturated-magnet approximation, accounting for nonuniform magnetization. Here, we combine thin-film characterization of Co, Co/Ta multilayers, and CoFe films with nanoscale stray-field measurements using NV-center magnetometry in the unsaturated regime to establish a reliable micromagnetic simulation framework. We show that CoFe micromagnets generate antisymmetric fields in double
quantum-dot geometries exceeding +/- 100mT, owing to their high saturation magnetization and favorable magnetocrystalline anisotropy. For
spin qubits coupled to microwave resonators, the predicted
spin-
photon coupling reaches $\left| g_s/g_c \right| \approx 0.5$, where $g_c$ denotes the charge-
photon coupling strength of the underlying charge
qubit, highlighting the potential for high-fidelity operations in
circuit QED architectures.
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All authors Sandrine Lopes, Quentin Schaeverbeke, Matthieu M. Desjardins, Daniel Lacour, Michel Hehn, François Montaigne
Materials Science
Spontaneous Nanopatterning and Strain Relaxation in SiGe Layers Grown by Oxidative Solid Phase Epitaxy
Sophie E. Bierer, Trevor R. Smith, Arezoo Mafi et al. (+5 more)
The wafer-scale monolithic integration of III-V materials on Si would lead to revolutionary optoelectronic hardware for data, computing and other applications. However, heteroepitaxy of III-Vs on Si requires overcoming the large
lattice and thermal mismatches between the materials and reducing threading dislocations densities. In this work, we explore the oxidative solid phase epitaxy (SPE) of Ge+ implanted Si(111) to form ultra-thin strain-relieving SiGe metamorphic buffer layers for heteroepitaxy on Si. The SPE process is shown to result in a nanopatterning of the Ge concentration variation across the sample surface, visible by scanning and transmission electron microscopy (SEM and TEM). The concentration patterning is the result of a hexagonal network of Shockley partial dislocations at the SiGe/Si interface. Analyzing the pattern spacing observed by SEM is demonstrated as an easy, non-destructive method for obtaining the local strain state of SiGe layers. This work is important for engineering ultra-thin SiGe metamorphic buffer layers for III-V optoelectronics heteroepitaxy on the silicon platform.
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All authors Sophie E. Bierer, Trevor R. Smith, Arezoo Mafi, Sunzhuoran Wang, Chengqian Liao, Vatsalkumar Patel, Andrew P. Knights, Ryan B. Lewis
Quantum Physics
Quantum error-correcting codes from aperiodic monotiles: the Hat and the Spectre
Josep Batle and Adam Bednorz
Li and Boyle showed that the Penrose tiling defines a
quantum error-correcting code: superpositions of tilings over isometry orbits protect
quantum information against erasure of any bounded region. We extend the construction to the aperiodic monotiles discovered by Smith, Myers, Kaplan and Goodman-Strauss. For the Hat, we prove strong local indistinguishability for all Hat tilings, and we prove local recoverability unconditionally for all nonsingular Hat tilings via the
torus parametrization of the underlying cut-and-project scheme. The remaining singular case reduces to one sharply posed
geometric question – can a region that is a union of hats be retiled a second way? – which we verify computationally has no counterexample up to a substantial scale: a certified $2490$-tile patch admits precisely one tiling by hats, so all $2^{2490}$ of its tile-subregions retile uniquely. Unlike the Penrose, Ammann-Beenker and Fibonacci tilings, both monotiles form two local-indistinguishability classes, so their code spaces split into two erasure-correcting sectors carrying a superselected classical label. Whether the label survives depends on which isometries are gauged: the Spectre's classes are exchanged by a $30^{\circ}$ rotation and merge once all proper isometries are gauged, whereas the Hat's are exchanged only by reflections. Under the physically natural gauge group $SE(2)$, the Hat code therefore stores one robust classical bit – the handedness of its long-range order, readable in any bounded window with separation $\Delta = |K|\sqrt{5}/3$ – alongside its protected
quantum sectors. It is the reflexible monotile, not the
chiral one, that carries the chirality bit. We give the exact Perron-Frobenius data of both codes, including the per-class reflected-Hat frequencies $(3\mp\sqrt{5})/6$ and the Spectre orientation-class frequencies $(5\pm\sqrt{15})/10$.
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General Relativity and Quantum Cosmology
Quasinormal Modes of Self-Dual Loop Quantum Gravity Corrected Kerr Black Holes
Yu Wang, Meilin Liu and Haiguang Xu
We investigate scalar quasinormal modes and ringdown signals of a rotating loop
quantum gravity black hole constructed via the revised Newman–Janis
algorithm. The spacetime incorporates two
quantum parameters, the polymeric parameter $P$ and the minimal area parameter $a_0$, and reduces to the Kerr spacetime in the classical limit. Using the sixth-order WKB approximation and time-domain integration, we analyze the effective potential, quasinormal mode spectrum, and ringdown dynamics. The polymeric parameter $P$ systematically reduces the oscillation frequency $\mathrm{Re}(\omega)$, while the
spin parameter $a$ enhances it. The time-domain signals exhibit clear dependence on the multipole number $\ell$ and overtone index $n$. Our results provide a theoretical framework for understanding the effects of loop
quantum gravity corrections on black hole perturbations and gravitational-wave ringdown signals.
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Astrophysics of Galaxies
On the reconstruction of the Rotation Curve for Milky Way and its spacetime implications: a Machine Learning approach
Aritra Sanyal, Swapan Das, Farook Rahaman et al. (+1 more)
We propose a machine learning-assisted analytical reconstruction of the Milky Way rotation curve and discuss its implications in a relativistic spacetime context. The rotation curve is reconstructed using 73 observational data points over the range 0.1-95.56 kpc, and we compare the performances of Ridge regression, LASSO regression, and feed-forward neural networks using a physically motivated functional basis. Ridge regression yields the most stable prediction with R2 = 0.9824 +/- 0.0064 and RMSE = 3.75 km/s, while retaining analytical interpretability. We embed the reconstructed velocity profile into a static, spherically symmetric spacetime, enabling the determination of the
redshift function and the mass function through Einstein's equations. We verify that all energy conditions are satisfied, the sound speed remains subluminal, the circular orbits are stable, and the gravitational energy is negative, confirming the attractive nature of
gravity. This framework provides a statistically validated, data-driven alternative to conventional dark matter
halo models and establishes a direct connection between kinematical observables and relativistic spacetime geometry.
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All authors Aritra Sanyal, Swapan Das, Farook Rahaman, Saibal Ray
Quantum Physics
Collective Enhancement of Nuclear Excitation for a Nuclear Quantum Battery
Pravin Kumar Dahal, Kieran Hymas, Jack Muir et al. (+1 more)
Current implementations of
quantum batteries are constrained by limited energy density and short retention times associated with the electronic or molecular excitations. Here we propose a
nuclear quantum battery based on collective excitation of the $^{57}$Fe
nuclei of density $n$ embedded in a planar hard X-ray waveguide. Using a Green function waveguide-QED description, we study charging via excitation beyond linear response, where saturation and drive back-action reshape the incident pulse. We introduce a self-consistent waveform-engineering protocol that inhibits local radiative decay in the waveguide thus promoting absorption into high-lying collective
nuclear excitation
manifolds. We show an enhanced excitation cross section of the
nuclear ensemble which yields superlinear charging, with maximum studied energy density scaling approximately like $n \sqrt{n}$. Our results provide a route to high-energy-density
quantum charging at hard X-ray energies using contemporary X-ray sources and waveguide architectures by identifying nonlinear, collectively enhanced absorption as a key mechanism for
nuclear quantum battery operation.
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All authors Pravin Kumar Dahal, Kieran Hymas, Jack Muir, James Q. Quach
Quantum Physics
Structure-Agnostic Unitary Learning from Quantum Observable Dynamics with Application to Hamiltonian Identification
Mohamed Berkani
We present a variational
algorithm for learning an unknown
quantum unitary from time-series observable measurements, with no structural assumption about the target. The core separation: a hardware-efficient parametrised
circuit learns the
evolution operator U via observable matching;
Hamiltonian identification follows as classical post-processing via
matrix logarithm, when the target happens to be exp(-iH*tau). Three experiments establish the method's generality. First, a noiseless proof of correctness with exact gradients (L-BFGS-B) achieves MSE 1.61e-14 and recovers all
Hamiltonian coefficients to six decimal places. Second, a gate-learning experiment fits CNOT, iSWAP, and a Haar-random SU(4) element – none generated by any fixed
Hamiltonian – all to process fidelity 1.000000, confirming the method does not rely on Trotterisation structure. Third,
quantum deployment via SPSA-Adam under Qiskit Aer depolarising noise (p1=0.001, p2=0.01, Nshots=1024) recovers all three Ising
Hamiltonian terms with errors below 8%. The optimiser, SPSA-Adam, combines SPSA's hardware-efficient two-point gradient estimation with Adam's adaptive moment updates. A four-stage moment-warm curriculum progressively extends the training horizon, converting a global non-convex problem into a sequence of well-posed local ones.
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High Energy Physics (Phenomenology)
Particle production from bubble collisions
Anish Ghoshal, Pratyay Pal and Alessandro Strumia
Collisions of ultra-relativistic bubbles during cosmological phase transitions can produce particles much heavier than the transition scale. Previous analyses modelled this process as the off-shell decay of the scalar background. We show that its results parametrically overestimate hard particle production and depend on the gauge choice and the coordinate choice in field space. We propose an alternative formalism, analogous to the partonic description of high-energy collisions. In the ultra-relativistic limit, the colliding bubbles undergo nearly free passage and hard production arises from on-shell scatterings among the quanta constituting the Lorentz-contracted walls. We apply this approach to heavy scalar,
fermion, and vector particle production, and study the implications for dark matter, leptogenesis, graviton production and
primordial gravitational waves.
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Quantum Physics
Locality of deep thermalisation through the lens of entanglement teleportation
Saptarshi Mandal, Alan Sherry and Sthitadhi Roy
Deep thermalisation characterises the emergence of universal
quantum state ensembles on subsystems due to projective measurements on their complement. We study the notion of locality, or lack thereof, in this phenomenon by considering a subsystem partitioned into two disjoint subregions which remain causally disconnected at all times under
unitary dynamics. We show that the onset of deep thermalisation in this geometry is fundamentally bounded by measurement-induced
entanglement teleportation between the subregions. While measurements on the environment generate
entanglement across the disconnected partitions – suggesting an apparent non-locality – we demonstrate that generic locally interacting systems exhibit an emergent locality. Specifically, the timescales for both deep thermalisation and
entanglement teleportation scale logarithmically with the distance separating the subregions. Exceptions to this include special
circuits where the randomness of the measurement outcomes is perfectly transmitted to the ensemble of states of the subsystem, conditioned on the outcomes; in such cases the timescale for deep thermalisation is finite leading to genuine non-locality.
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Strongly Correlated Electrons
Single-component twisted $\mathbb{Z}_3$ orthogonal metal in an $e/3$-anyon fluid
Zhaoyu Han, Ashvin Vishwanath and Eslam Khalaf
We propose an unconventional metallic phase emerging upon doping the $1/3$ Laughlin Fractional Chern
insulator, which can serve as a parent state to anyon superconductivity with arbitrary
chiral central charge. It is a twisted $\mathbb{Z}_3$ orthogonal metal: a state with vanishing electron quasiparticle weight but a single well-defined
Fermi surface of emergent charge-$e/3$
fermions coupled to a Dijkgraaf-Witten twisted $\mathbb{Z}_3$ gauge field. It is manifestly symmetric under the projective action of translations on the three low-energy valleys and is fully gapped in the valley sector. Pairing this fractionalized
Fermi surface then removes the topological order and produces a family of
superconductors whose
chiral central charge is directly set by the BdG band
topology of the paired $e/3$
fermions, while the angular momentum of the physical order parameter is constrained to be a multiple of three. This scenario provides a route to superconducting states beyond anyon-superconductivity constructions based on $2e/3$ anyons. The metallic phase itself carries distinctive “fractional Fermiology” signatures: $e/3$ shot noise, anomalous
quantum oscillations, and a $6\pi$ ac Josephson effect when it mediates the Josephson coupling between
superconductors. We construct explicit wavefunction ansatz realizing the phase, and discuss energetics considerations that might favor this state over competing metallic states. We show that the construction extends to higher Laughlin states but not to Jain states.
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Soft Condensed Matter
Mass-induced Mpemba effect in a polymer-bead system
Hosung Kwak, Yongjoo Baek and Hawoong Jeong
We propose a physically motivated model in which the Mpemba effect is induced by the system's inertia. The model describes a
polymer undergoing a denaturation transition whose force-extension curve contains a weak-force plateau that slows relaxation. In the presence of inertia, a farther initial state can reach and cross the plateau sooner, producing the Mpemba effect. Increasing the bead mass broadens the range of initial conditions over which this mechanism operates. A similar mechanism also generates the inverse Mpemba effect.
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Quantum Physics
Dynamic Entanglement Distribution for Multi-User and Multi-Protocol Quantum Networking
Rui Wang, Marcus J. Clark, Obada Alia et al. (+8 more)
Dynamic
entanglement distribution is a key requirement for scalable, multi-user and multi-protocol
quantum networks. We demonstrate a metropolitan-scale
entanglement-based
quantum communication network enabled by a
quantum reconfigurable optical add-drop multiplexer (q-ROADM), which dynamically distributes polarisation-entangled
photon pairs from a broadband source to six users over deployed campus and metropolitan fibre. The network supports programmable full-mesh, partial-mesh and sliced sub-network configurations, enabling flexible allocation of
entanglement resources according to link condition and service requirement. We demonstrate stable six-user full-mesh operation over more than 150 hours, compare full-mesh and time-shared partial-mesh strategies under different source and detector conditions, and realise
quantum network slicing with optional/additional interconnection links. We also show that the same infrastructure can support different
quantum protocols by showcasing Secure Inaugural Authentication-Transfer (SIAT) combined with Network flooding over multiple paths to improve the security of onboarding a new user. These results demonstrate a q-ROADM-enabled
entanglement distribution architecture as a novel route towards reconfigurable, service-oriented
quantum networking over optical fibre infrastructure.
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All authors Rui Wang, Marcus J. Clark, Obada Alia, Sima Bahrani, Djeylan Aktas, Matej Peranić, Mario Stipčević, Martin Lončarić, John Rarity, Siddarth K. Joshi, Dimitra Simeonidou
High Energy Physics (Theory)
Relativistic time-commutative dynamics with $\kappa$-plane noncommutativity
Alessandro Moia, Stefano Stocchetti and Giovanni Amelino-Camelia
In the last decades, spacetime noncommutativity and the associated deformations of relativistic
symmetries have attracted a lot of interest, as several phenomenological windows into
quantum gravity are approaching genuine Planck-scale sensitivity. However, the physical significance of the mathematical structures introduced to deal with spacetime noncommutativity is still debated, and some crucial pieces are missing or poorly understood. From time to time it has been suggested that valuable insight into these conceptual challenges could come from the analysis of appropriately designed first-quantized toy models, in which major technical and interpretive issues can be effectively managed or sidestepped altogether. In this paper we take seriously this suggestion and develop the first fully consistent and fully relativistic first-quantized model of two particles propagating and interacting on a noncommutative spacetime. The specific spacetime noncommutativity implemented in our model, which we call 'time-commutative $\kappa$-plane', had already been proposed as a suitable arena for a first-quantized analysis, but previous studies were mostly heuristic and failed to provide a full description of the deformed relativistic
symmetries. We here go much beyond those pioneering attempts: we find a full characterization of the appropriate deformed Poincaré
symmetry algebra as well as its Galilean limit; we build a single-particle
quantum model carrying an irreducible representation of the deformed Galilei
algebra; we exhibit two consistent, Galilean-relativistic descriptions of a system of two
quantum particles interacting via a deformed harmonic potential, finding that the structure of the two-particle
symmetry generators is intimately connected with the deformation of the interaction law.
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Mesoscale and Nanoscale Physics
Long-range and steady-state entanglement of nitrogen vacancy centers using microwaves as a drive and synthetic antiferromagnet as a dissipator
Federico Garcia-Gaitan and Branislav K. Nikolic
The search for optimal schemes and dissipative environments that can mediate long-range
entanglement between two distant nitrogen-vacancy centers (NVCs) in diamond has been the subject of vigorous efforts over the past decade due to potential applications of such microscopic solid-state
qubits in
quantum sensing and
quantum computing. However, stabilizing
entanglement of NVCs into a steady state poses a significant challenge, typically requiring tuning the environment out of
equilibrium. Here we microscopically and rigorously derive a Lindblad
quantum master equation (QME) for a system of two driven-dissipative NVCs, where the drive is microwave radiation and dissipation is provided by a single
magnetic bath that is kept in
equilibrium. The jump operators within the Lindblad QME are expressed in terms of Keldysh Green's functions defined as correlators of dipolar field operators of the bath. This QME makes it possible to predict precise conditions for long-range and steady-state
entanglement of two NVCs, while suggesting that a synthetic antiferromagnet could be an optimal choice for a dissipative environment. By using realistic parameters from available experiments, we estimate steady-state concurrence reaching $\mathcal{C}\simeq 0.28$ for two NVCs separated by $\sim 100 \: \mathrm{nm}$.
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Quantum Physics
Coulomb blockade in microscopic material defects as a source of decoherence and noise in solid-state quantum circuits
R. Banerjee, L. P. Lindoy, M. Hegedus et al. (+9 more)
A critical limitation of solid-state
quantum devices arises from the materials from which they are fabricated: uncontrolled surfaces, interfaces, and structural imperfections introduce numerous sources of loss and decoherence. Despite extensive efforts, linking these decoherence mechanisms to their microscopic material origins – essential for developing effective mitigation strategies – remains an outstanding challenge that has slowed coherence improvements. Here, using scanning gate microscopy on live superconducting
circuits we identify a previously unrecognised decoherence mechanism originating from Coulomb blockade and microwave-driven charge tunnelling in metallic grains. Such grains are ubiquitous in thin-film devices fabricated by standard lithography processes. By characterising multiple defects across different devices, we find such defects to be as common and as debilitating to device performance as two-level system (TLS) defects, while originating from a fundamentally different physical mechanism. Importantly, conventional characterisation techniques would misattribute this loss to other, microwave power-independent processes. Our observations thus reveal a widespread source of decoherence in superconducting
circuits, challenging the prevailing paradigm that coherence lifetimes are primarily limited by TLS defects. Eliminating metallic grains during fabrication provides a clear and practical route to suppress this mechanism, offering a pathway towards improved coherence and reduced noise in microwave-based solid-state
quantum devices.
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All authors R. Banerjee, L. P. Lindoy, M. Hegedus, A. Hutcheson, T. Hawkins, E. Daghigh-Ahmadi, S. Samaddar, T. Barker, J. P. Goff, A. Ya. Tzalenchuk, I. Rungger, S. E. de Graaf