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Physics

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Thursday 2 July

Statistical Mechanics

Non-equilibrium phase transition in the Brownian Ising Model: field theory, renormalization group, and exact results

Mattia Scandolo and Luca Di Carlo

We present a complete field-theoretical renormalization-group (RG) analysis of the Brownian Ising Model (BIM), in which a $\mathbb{Z}_2$ order parameter is coupled to a passive conserved density, breaking detailed balance. Using the Martin-Siggia-Rose formalism and an $\epsilon=4-d$ expansion, we show that this density-order parameter coupling is RG-relevant below four dimensions and drives the system to a new non-equilibrium fixed point, distinct from the Ising universality class. Critical exponents are computed at lowest nontrivial order, some of which require a dedicated two-loop analysis. At large scales, the density acts as an effective noise that is white in time but long-range in space, enhancing order-parameter fluctuations and producing a negative anomalous dimension $\eta$. A defining feature of the new class is that the correlation and response functions acquire different anomalous dimensions, $\eta \neq 2 - \gamma / \nu$ - a direct, observable signature of fluctuation-dissipation-theorem violation at large scales that cannot occur in equilibrium. We also find a small correction-to-scaling exponent, implying large preasymptotic corrections that must be accounted for in numerical and experimental tests. We further derive a set of relations among renormalization factors that hold to all orders in perturbation theory, following from the linearity of the density dynamics and an emergent shift symmetry. These yield an exact scaling relation $\nu = 2/(d+z-2)$ at the BIM fixed point and establish that the Ising universality class, as well as that of quenched diluted-Ising, is unstable in $d=3$. This establishes the BIM fixed point as the unique infrared attractor for any nonzero diffusion constant.
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Astrophysics of Galaxies

The MIRI Early Obscured-AGN Wide Survey (MEOW): A Population of Hidden AGN at $z \gtrsim 5$ Revealed by JWST/MIRI Imaging

Gene C. K. Leung, Anna-Christina Eilers, Ryan Endsley et al. (+25 more)

We present the MIRI Early Obscured-AGN Wide Survey (MEOW), a JWST/MIRI imaging survey designed to detect dust-obscured active galactic nuclei (AGN) across cosmic time, with a particular focus on the high-redshift universe at $z \gtrsim 5$. MEOW observes the GOODS-N and GOODS-S fields with 43 pointings covering 95 arcmin$^2$ with the F1000W and F2100W filters, reaching depths of 0.5 and 3.6 $\mu$Jy ($5\sigma$), respectively. Using spectral energy distribution (SED) modeling combining MEOW photometry with archival HST, JWST/NIRCam, and SCUBA-2 data, we identify a sample of 16 MIRI-selected AGN at $z = 4.5$–$7.2$ (12 spectroscopically confirmed), spanning bolometric luminosities of $L_{\rm bol} = 10^{44.6}$–$10^{46.4}$~erg~s$^{-1}$. Twelve of the 16 AGN are newly identified in this work, including at least five narrow-line AGN representing the obscured population to which broad-line spectroscopic searches are insensitive. Two broad-line AGN exhibit markedly different mid-infrared emission properties, consistent with one being a little red dot (LRD) and the other either a typical AGN or an LRD with unusually strong hot-dust emission. The MIRI-selected AGN bolometric luminosity function at $z = 4.5$–$6$ yields number densities comparable to those of broad-line AGN and LRDs, suggesting that obscured AGN contribute significantly to the total AGN census at these epochs. The narrow-line AGN reside in diverse host environments, with evidence for both circumnuclear and host-galaxy-scale obscuration, pointing to multiple physical mechanisms at work. These results establish JWST/MIRI imaging as an indispensable component of a multi-faceted approach to a complete census of early supermassive black hole growth.
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All authors Gene C. K. Leung, Anna-Christina Eilers, Ryan Endsley, Steven L. Finkelstein, Micaela B. Bagley, Guillermo Barro, Anton M. Koekemoer, Pablo G. Pérez-González, Nor Pirzkal, Bren E. Backhaus, Teodora-Elena Bulichi, Jaclyn B. Champagne, Katherine Chworowsky, Nikko J. Cleri, Mark Dickinson, Xiaohui Fan, Seiji Fujimoto, Norman A. Grogin, Allison Kirkpatrick, Dale D. Kocevski, Vasily Kokorev, Rebecca L. Larson, Ray A. Lucas, Fabio Pacucci, Casey Papovich, Anthony J. Taylor, Natalia C. Villanueva, Guang Yang

Astrophysics of Galaxies

Helical radio jets as probes of magnetised cluster environments: Periodic Faraday Rotation Revealed in the Corkscrew Galaxy by POSSUM

Sarah N. Bradbury, C. S. Anderson, N. M. McClure-Griffiths et al. (+14 more)

Jets from active galactic nuclei (AGN) that exhibit regular plane-of-sky oscillations may provide a probe of magnetised plasma within the jets and their local intracluster medium (ICM). If such morphologies trace three-dimensional helices, path length differences between near and far sides of the flow might imprint quasi-periodic signatures in Faraday rotation. We present ASKAP Band 2 (1296-1440 MHz) polarimetric observations of a helical-tailed radio galaxy (the "Corkscrew Galaxy") from early science data from the POlarisation Sky Survey of the Universe's Magnetism (POSSUM), and test whether its quasi-periodic morphology produces signatures in Faraday rotation. We detect significant RM oscillations with a spatial period of (342 +/- 101) arcsec, consistent within the Rayleigh resolution limit with the jet's lateral deviations ((290 +/- 72) arcsec). Cross-correlation analysis reveals systematic variation along the jet: the eastern section shows alignment between jet deviation and RM, consistent with a jet-associated or sheath-like Faraday screen, while the western section exhibits a phase shift, indicating a transition in the dominant Faraday-rotating medium and possible contribution from the local ICM. These results demonstrate that quasi-periodic RM signatures can disentangle the dominant Faraday-rotating medium in AGN jets, and show that in some embedded radio galaxies the dominant RM contribution arises near the source rather than the cluster foreground. We also outline reliability criteria required to avoid false positive detections and inadequate sampling. Helical jet structures therefore show strong promise as probes of magnetised cluster environments, a capability that will expand in the SKA era.
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All authors Sarah N. Bradbury, C. S. Anderson, N. M. McClure-Griffiths, Y. K. Ma, A. J. M. Thomson, L. Rudnick, S. P. O'Sullivan, B. M. Gaensler, B. S. Koribalski, E. L. Alexander, Takuya Akahori, L. Baidoo, E. Carretti, G. Heald, H. Sakemi, T. Vernstrom, J. West

Cosmology and Nongalactic Astrophysics

Limits on global cosmic birefringence using radio sources

Richard A. Battye, Neal Jackson and Ian Browne

We have made measurements of the difference between the position angle (PA) on the sky and the polarization position angle (PPA) of radio sources using data from a combination of the Radio Fundamental Catalogue (RFC) across a range of frequencies between 2.7 and 15~GHz and Cosmic Lens All Sky Survey (CLASS) which observes polarization at 8.4~GHz (X-band). For the 2111 sources with jet PAs measured in the X-band and a known redshift, the distribution is peaked at $\approx 0^{\circ}$ as expected for no birefringence and it can be modelled by two populations: one which is a Gaussian with mean $\mu_{\beta}=(0.2\pm 1.0)^{\circ}$ and standard deviation $\sigma_{\beta}=(14.7\pm 1.1)^{\circ}$ and the other a uniform distribution of sources which are a fraction $f_\beta=0.72\pm 0.02$ of the total. Uncertainties in $\mu_\beta$ can be reduced to $\approx 0.6^{\circ}$ by stacking measurements of the PA from other wavebands. We find that limits of $\approx 0.1^{\circ}$ might be possible with a sample of $\sim 10^5$ similarly selected sources and that this could provide a confirmation of recent claims of global birefringence made using the Cosmic Microwave Background observations from the Planck satellite.
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Astrophysics of Galaxies

Polar coordinate transformations for machine learning based dark matter subhalo detection in strong gravitational lenses

Jacob M Campbell, Simon Dye, Emma Chapman et al. (+1 more)

Strong gravitational lensing provides a powerful probe of dark matter, particularly on small scales where the gravitational effects of dark matter subhalos within galaxies can manifest as perturbations within the extended arcs of gravitationally lensed sources. We investigate whether transforming lensed images into polar coordinates improves the ability of convolutional neural networks to infer subhalo mass. We introduce a machine learning architecture that outputs a prediction uncertainty alongside a mass prediction to enable assessment of network reliability. Using simulated Hubble Space Telescope observations, we compare our models trained on Cartesian and polar representations under different initialisation schemes, noise levels, and subhalo concentrations ($c=60$, $c=30$). We find that polar-transformed inputs consistently yield higher subhalo detection fractions than standard Cartesian images across all tested masses. For subhalos with mass $10^9M_\odot \leq M \leq 10^{9.5}M_\odot$, the fraction of subhalos the network is able to detect increases by $\sim 15$ per cent. Pretrained networks outperform randomly initialized networks, and the polar transform consistently improves network performance in both low signal-to-noise data and for lower-concentration subhalos. The relative improvement is highest in regimes where subhalo perturbations are most difficult to detect, such as low signal-to-noise data or systems containing low concentration subhalos. These results demonstrate that presenting strong lensing images in a polar representaion provides a computationally inexpensive way of improving CNN-based subhalo detection.
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All authors Jacob M Campbell, Simon Dye, Emma Chapman, Adam Moss

Instrumentation and Methods for Astrophysics

Astrometric Calibration of the 4-m International Liquid Mirror Telescope Observations

Vibhore Negi, Naveen Dukiya, Gokul Singh Mehra et al. (+12 more)

The 4-m International Liquid Mirror Telescope (ILMT) is a dedicated time domain survey telescope that continuously scans the zenithal sky over the Indian Himalayas in the g', r' and i' optical bands. Its unique capability to repeatedly image the same strip of sky every night makes it a highly useful instrument for the photometric and astrometric studies of Solar System, Galactic and extragalactic objects. We present a robust astrometric calibration pipeline developed for the ILMT data obtained in the time delay integration (TDI) mode. The pipeline uses a linear transformation model from pixel to world coordinates, with a second order correction for the asymmetric optical distortions introduced by the telescope's optical corrector, and ties the astrometric solution to the Gaia DR3 reference frame. The pipeline is integrated to the routine ILMT data processing workflow. Using data from the first four observing cycles (2022-2025), we present the first assessment of the astrometric performance of the pipeline based on positional residuals of sources cross-matched with Gaia DR3. The pipeline achieves a typical astrometric precision of ~100 milliarcseconds (mas), reaching ~70-80 mas for moderately bright sources (G~16.5-18.5). These results, based on 347 nights of data, demonstrate the stability and reliability of ILMT astrometry over multi-year timescales. The astrometrically calibrated data from these four observing cycles have been made publicly available to the astronomical community. This work establishes a validated framework for precision astrometry with zenith-pointing TDI surveys and provides a foundation for future time-domain studies with ILMT, including variability characterization, transient localization, and long-term positional monitoring.
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All authors Vibhore Negi, Naveen Dukiya, Gokul Singh Mehra, Bhavya Ailawadhi, Monalisa Dubey, Sara Filali, Paul Hickson, Brajesh Kumar, Priyanshi Kumari, Sapna Mishra, Kuntal Misra, Bikram Pradhan, Kumar Pranshu, Jean Surdej, Sarvesh Kumar Yadav

Statistical Mechanics

Non-equilibrium coupling to a diffusing density breaks Ising universality

Mattia Scandolo, Johannes Pausch, Michael E. Cates et al. (+1 more)

The Ising universality class is remarkably robust to non-equilibrium perturbations, which generically flow to zero under renormalization. We show that this robustness fails when an order parameter is coupled nonreciprocally to a conserved diffusive density. Below $d_c=4$, the renormalization group flows to a fast-diffusion fixed point at which the density acts as a long-range multiplicative noise, producing a novel universality class. The non-equilibrium nature of the fixed point is manifest in the large-scale violation of the fluctuation-dissipation relations, reflected in a splitting of the scaling exponents of the two-point correlation and response functions–a measurable hallmark of non-equilibrium critical fluctuations. A two-loop calculation establishes the stability of this fixed point but yields a small correction-to-scaling exponent $\omega\approx0.020$ in $d=3$, implying strong finite-size corrections. An all-orders modified Harris criterion $\nu>2/(d+z-2)$ confirms that the BIM fixed point governs criticality in $d=3$, with Ising universality recovered only at $d=2$.
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All authors Mattia Scandolo, Johannes Pausch, Michael E. Cates, Luca Di Carlo

Earth and Planetary Astrophysics

Azimuthal brightness modulation reveals hidden rings in CI Tau

C. E. Scardoni, G. P. Rosotti, F. Zagaria et al. (+4 more)

Protoplanetary disks often host substructures such as rings and gaps, which trace key processes in planet formation and dust evolution. However, narrow rings may remain unresolved due to limited observational resolution, hiding critical information about early planetesimal formation and the amount of dust present. We apply the azimuthal brightness modulation method, based on the modulation produced by multiple unresolved optically thick rings embedded in an optically thin background Scardoni+2024, to multi-wavelength ALMA observations of CI Tau to identify unresolved rings and constrain their geometry and optical depth. We analysed CI Tau archival ALMA continuum observations in bands 3, 6, and 7, extracting azimuthal brightness profiles along narrow annuli and comparing them with forward modeled synthetic observations of inclined disks containing unresolved rings. We detect the azimuthal signature at $\sim22$ au in all three bands, consistent with unresolved, optically thick rings embedded in a lower optical depth background. Multi wavelength modelling constrains the rings' geometry and optical depth, consistent with conditions expected for streaming instability and early planetesimal formation. Our results demonstrate the applicability of this azimuthal signature technique to real disks, reveal fine scale dust substructures in CI Tau, and illustrate a new method to study the early stages of planet formation below the nominal resolution limit.
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All authors C. E. Scardoni, G. P. Rosotti, F. Zagaria, A. Ribas, M. Villenave, C. J. Clarke, R. A. Booth

High Energy Physics (Phenomenology)

Dark Matter in the General 2HDM with Extra Top Yukawa Couplings

Leon M.G. de la Vega and Mohamed Krab

We extend the general two Higgs doublet model (G2HDM), which introduces extra Yukawa couplings, by an additional real scalar singlet (G2HDM+S), providing a viable scalar dark matter (DM) candidate. This setup provide a viable UV completion of top-window dark matter scenarios, in which DM communicates with the standard model predominantly through the top quark. We analyze the constraints on the visible scalar sector from Higgs signal strength measurements and direct searches for additional Higgs bosons at the LHC, and those on the dark sector from cosmological observables, including the observed DM relic density and spin-independent direct-detection as well as indirect detection. Within the surviving parameter space, we identify a rich and diverse LHC phenomenology governed by the interplay between the singlet portal, the extended Yukawa sector, and the heavy scalar mass hierarchy. To facilitate experimental investigation, we propose six benchmark scenarios spanning the singlet-portal, bosonic-cascade, fermiophilic, and flavor-violating regimes. In the latter, the nondiagonal top-charm coupling $\rho_{tc}$ induces the production channel $cg \to tH$, allowing the top quark to serve as a trigger for an otherwise invisible $H\to SS$ signal. This flavor-violating DM production is a distinct feature of the G2HDM+S.
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High Energy Physics (Theory)

The giant graviton expansion in AdS$_5\times$SE$_5$

Alfredo González Lezcano, Leopoldo A. Pando Zayas and Augniva Ray

We study giant graviton-like D3-branes as probe configurations in type IIB supergravity backgrounds AdS$_5\times$SE$_5$, with emphasis on the structure of the five-dimensional Sasaki-Einstein manifolds SE$_5$. These configurations wrap supersymmetric three-cycles in SE$_5$ and rotate at the speed of light along the Reeb direction. We formulate the general problem in terms of the transverse Kähler potential and show that configurations carrying maximal angular momentum can be described by loci where the transverse Kähler potential diverges in suitably chosen coordinates. We quantize a particular set of excitations, similar to those considered in the AdS$_5\times S^5$ case, and show that they are governed by a Fock-Darwin problem with a conical deficit, which generalizes the Landau problem obtained for $S^5$. Succinctly, the information about the geometry of SE$_5$ is encoded in the form of the external potential and the conical deficit. We compute a protected contribution to the superconformal index arising from quantized fluctuations of supersymmetric giant graviton configurations. For the explicit case of AdS$_5\times T^{1,1}$, we recover the finite-$N$ protected index of the dual quiver ${\cal N}=1$ superconformal field theory in the sector captured by a non-Abelian generalization of the quantized degrees of freedom.
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High Energy Physics (Phenomenology)

Muon lifetime and Fermi constant: an update

Alexander Eberhart, Matteo Fael, Alexander Keshavarzi et al. (+5 more)

We present an updated prediction for the lifetime of the muon including a detailed analysis of all relevant uncertainties. Our prediction includes QED corrections up to order $\alpha^3$ and state-of-the-art hadronic contributions based on dispersive methods. Radiative corrections and finite-electron-mass effects are parametrized by the correction factor $\Delta q$ in $\tau_\mu^{-1}=G_F^2m_\mu^5(1+\Delta q)/(192\pi^3)$, for which we obtain $\Delta q=(-4\, 384\, 678 \pm 34)\times 10^{-9}$. This reduces the uncertainty associated with $\Delta q$ by an order of magnitude compared to the previous prediction at order $\alpha^2$. We use our results to provide an updated value of the Fermi coupling constant, $G_F=1.166\,378\, 59 \, (59) \times 10^{-5} \, \mathrm{GeV}^{-2}$. Further improvements will require better measurements of the muon lifetime and mass.
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All authors Alexander Eberhart, Matteo Fael, Alexander Keshavarzi, Daisuke Nomura, Kay Schönwald, Matthias Steinhauser, Thomas Teubner, Aidan Wright

High Energy Astrophysical Phenomena

Non-thermal emission in jets and winds: Expected emission and spectral index distributions

M. Meenakshi, D. Mukherjee, G. Bodo et al. (+5 more)

The origin of synchrotron emission in compact radio sources associated with active galactic nuclei (AGN) remains poorly understood. In a series of papers, we have examined diagnostic tools to disentangle the dominant underlying processes. In this study, we investigate the in situ evolution of cosmic-ray electrons (CREs) in compact AGN jets and winds, and examine how their evolution shapes the resulting observable radio properties. In jets, CREs experience multiple shock interactions as they propagate along the spine toward the hotspot and flow into the cocoon via backflows. In winds, CREs are predominantly accelerated at the Mach disc, with occasional re-acceleration within turbulent cocoon backflows. The continuous mixing of different CRE populations within the cocoon produces observational signatures that cannot be inferred from instantaneous conditions alone. In all jet simulations, spectral indices are flattest near the hotspot and steepen progressively away from the hotspots. In winds, spectra steepen with increasing distance from the Mach disc, with this trend becoming more pronounced at high radio frequencies due to radiative losses. We find the Mach disc to be a significantly more efficient CRE acceleration site than the forward shock in winds, which weakens as the wind expands to large scales. Since morphology, especially at low resolution, can be ambiguous for compact sources, spatially resolved spectral indices, particularly when combined with emission and polarization signatures, can provide a powerful diagnostic.
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All authors M. Meenakshi, D. Mukherjee, G. Bodo, P. Rossi, C. M. Harrison, L. K. Morabito, P. Kharb, S. Silpa

Astrophysics of Galaxies

The largest sample of AGN outflows in dwarf galaxies using DESI DR1

V. Rodríguez Morales, M. Mezcua, Ragadeepika Pucha et al. (+40 more)

In the last decade, the presence of active galactic nuclei (AGN) outflows and feedback in dwarf galaxies ($\mathrm{M_\ast}$<$10^{10}\mathrm{M}_\odot$) has gained ground over supernova (SN) feedback as the main mechanism regulating star formation. In this work, we perform the first systematic search for AGN outflows in dwarf galaxies using the Dark Energy Spectroscopic Instrument Data Release 1 (DESI DR1). From $\sim$ 7 million galaxies at z$<$0.45, we identify ionized outflows through the detection of broad components in the [OIII]$\lambda5007$Åemission line. Galaxies are divided into dwarf and massive systems. Then, using emission-line diagnostic diagrams, we classify as star forming or AGN. We identify 1,502 AGN dwarf galaxies with outflow signatures. Comparing the distributions of star forming and AGN galaxies with outflows, we find that, among the 1,502 AGN dwarf galaxies with outflow signatures, AGN are the most likely drivers of the observed outflows in $\sim$83$\%$ of those with W$_{80}$ velocity $>250$ km s$^{-1}$. This constitutes the largest statistical sample of AGN outflows in dwarf galaxies to date. In massive galaxies, AGN dominance occurs above W$_{80}>350$ km s$^{-1}$. Therefore, two new velocity thresholds are proposed for identifying AGN-driven outflows in dwarf and massive galaxies. Besides, we find that outflows in dwarf galaxies are more likely to escape the dark matter halo than those in massive galaxies, allowing gas to be redistributed from the inner to the outer regions. This suggests that AGN outflows may have a major impact on dwarf galaxies.
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All authors V. Rodríguez Morales, M. Mezcua, Ragadeepika Pucha, C. Circosta, S. Juneau, M. Siudek, S. Panda, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, B. Dey, P. Doel, J.E. Forero-Romero, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, C. Hahn, R. Joyce, A. Kremin, A. Lambert, M. Landriau, L. Le Guillou, M. Manera, P. Martini, A. Meisner, R. Miquel, J. Moustakas, W.J. Percival, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, D. Sprayberry, G. Tarlé, B.A. Weaver, H. Zoo

Cosmology and Nongalactic Astrophysics

The youth of the intracluster medium. I. A non-parametric characterisation of the gas and electron number density profiles of $z \simeq 2$ protoclusters

David Vallés-Pérez, Annalisa Bonafede, Klaus Dolag et al. (+3 more)

Context. Protoclusters of galaxies are the earliest phase in the assembly of galaxy clusters and can provide invaluable information about plasma physics, cosmic magnetism, and cosmology. However, due to small angular sizes and cosmological dimming, observing the proto-intracluster medium (proto-ICM) associated with protocluster cores is far from trivial. Aims. We aim to provide a non-parametric description of the gas mass and electron number density profiles of the proto-ICM at $z = 2$, and to study their dependence on mass, dynamical state and central activity. Methods. We extract and analyse over $3800$ regions around protocluster cores with spherical-overdensity masses above $M_\mathrm{500c} > 10^{13} \, M_\odot$ out of a large simulated volume within the Magneticum suite. We study their density profiles, temperature structure, ionisation degree and electron number density as a function of mass and other secondary properties characterising dynamical state and central activity, extending from the central halo to the surrounding protocluster environment. Results. Protoclusters present moderate deviations from self-similarity in their density profiles and temperature structure, with a strong double-$\beta$ structure especially relevant at high masses and intense AGN accretion. Hot, ionised gas is only dominant at intermediate radii ($r \gtrsim [0.1-0.5] R_\mathrm{500c}$), where its density also correlates with mass and dynamical disturbance. Conclusions. These results constitute the basis for a forthcoming parametric calibration of proto-ICM density profiles, which could be useful for interpreting observables sensitive to the density and ionisation of the diffuse gas.
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All authors David Vallés-Pérez, Annalisa Bonafede, Klaus Dolag, Marco Balboni, Paolo Tozzi, Marika Lepore

Earth and Planetary Astrophysics

Contribution of White Dwarf Formation Kicks to the Free-Floating Planet Population

Alexander P. Stephan and Keivan G. Stassun

Free-Floating Planets (FFPs) are a distinct class of exoplanets that do not orbit stars but are nevertheless found to be very common. A variety of formation mechanisms have been proposed as their origin, such as "star-like" direct collapse from gas and dust clouds or ejection from young planetary systems via dynamical instabilities. Here, another possible formation scenario is explored that would instead apply for old planetary systems, in the form of White Dwarf (WD) formation kicks. Observations over recent years have shown that WDs experience a mild recoil kick during their formation from Asymptotic Giant Branch (AGB) stars. Here we show that, while WD formation kicks directly unbind only $\sim1\%$ of the known planet and exoplanet population, they drive dynamical instabilities in $\gtrsim40\%$ of known long-period multi-planet systems, likely leading to planet ejection and FFP generation by most WDs. We also show that FFPs generated via WD kicks will have undergone potentially significant and long-lasting heating via their host stars' enhanced AGB luminosities. Given the low ejection velocities due to the weakness of the WD kicks, such warmed FFPs can thus be associated with their former host stars for several Myr after formation. Therefore, WD formation kicks contribute a distinct, observationally identifiable FFP sub-population comprising a few percent of the Galaxy's FFPs, relevant for the design of future FFP surveys.
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Quantum Physics

Minimally invasive measurement of work in coherent quantum systems

Cyril Elouard, Karen Hovhannisyan and Giulia Rubino

A central challenge in quantum thermodynamics is to access work fluctuations in coherent processes without distorting the energetics of the unmeasured evolution. In standard two-point schemes, the initial energy measurement dephases coherent inputs, causing the measured average work to differ from that of the unmeasured evolution. Here, we develop an operational scheme for accessing work statistics for closed quantum systems based on the abstract notion of variation in the Heisenberg picture Hamiltonian. This scheme preserves energetically relevant coherences, thereby faithfully reproducing unmeasured work, while still producing positive probabilities. We derive modified Jarzynski and Crooks relations, as well as a thermodynamic uncertainty relation, identifying coherence-induced correction terms. Furthermore, we show that this scheme can reliably quantify the performance of a coherent engine in situations where the two-point energy measurement would suppress work output. In addition, the scheme requires only a single measurement and can predict the work associated with a subsequent unitary transformation. We exploit this feature to construct a Maxwell-demon protocol that can outperform energy-based feedback engines for coherent work extraction. Our results establish this scheme as a framework for accessing coherent work fluctuations without erasing the coherence that drives quantum thermodynamic performance.
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Cosmology and Nongalactic Astrophysics

First Search for Kaluza-Klein Gravitons and Radion Using Planck Data

Alexander P. Cassem and Soubhik Kumar

Heavy moduli and Kaluza-Klein (KK) gravitons from extra dimensions may evade terrestrial probes but can be produced during inflation, generating primordial non-Gaussianity (NG) through unavoidable couplings to density perturbations. In a warped five-dimensional (5D) model, we compute the full radion- and KK-graviton-mediated bispectra and perform the first search for these signals using Planck 2018 temperature and polarization data. We find no significant evidence for NG, with the maximum significance being $1.8\sigma$ for $m_{\rm KK}\approx 1.6H$. We also identify a 5D setup which naturally generates NG with $f_{\rm NL}\sim 1-50$, within the reach of future surveys.
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Astrophysics of Galaxies

Investigating the star formation histories of galaxies from Cosmic Dawn to the Epoch of Reionization with the Santa Cruz SAM

L. Y. Aaron Yung, Rachel S. Somerville, Steven L. Finkelstein et al. (+1 more)

The James Webb Space Telescope (JWST) has opened a new window onto galaxy evolution in the very early Universe. In this work, we leverage halo merger trees extracted from the GUREFT dark-matter-only cosmological simulation suite together with the Santa Cruz semi-analytic model (SAM) for galaxy formation to investigate the predicted star formation histories (SFHs) of galaxies from cosmic dawn (z ~ 14) to the end of the Epoch of Reionization (EoR; z~6). While we find that on average, median SFHs of galaxies across all masses are uniformly and rapidly rising over time from 14 < z < 6 as expected, individual galaxy SFHs show a range of diverse SFHs, even for a fixed terminal mass or redshift, with bursts and mini-quenching episodes in agreement with SFHs inferred from observations. The median lookback time to form the youngest 50% (t_50) and 90% (t_90) of galaxies' stars decreases weakly with increasing stellar mass, and strongly with the redshift of observation. For galaxies at z>12, we find typical values of t_50 < 30 Myr and t_90 < 70 Myr, a factor of ~3 to 4 shorter than for comparable galaxies near the end of EoR (z ~ 6). The young-star dominated nature of stellar populations in ultra-high-z galaxies implies that careful modelling of young stellar populations is crucial for obtaining accurate synthetic photometry. In addition, our results have important implications for interpreting observational indicators of star formation histories and timescales.
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All authors L. Y. Aaron Yung, Rachel S. Somerville, Steven L. Finkelstein, Kartheik G. Iyer

High Energy Physics (Phenomenology)

EFT Validity and Truncation Uncertainty from few Nuisance Parameters

Benoît Assi, Adam Martin and William Shepherd

An observable in an Effective Field Theory (EFT) is an expansion in a set of small parameters, no different than any other perturbation series. Truncating such a series expansion leaves the leading dropped term as the dominant source of error, and that term itself contains a calculable portion. We explore the partial calculation of this next-order error, available at dim-6$^2$ in SMEFT with no additional tools needed to simulate it, and explore how to efficiently use that partial calculation to model the next-order uncertainty in full using a minimal number of nuisance parameters. This estimate of the uncertainty of the EFT signal rate naturally imposes EFT validity by ensuring that bounds are driven by kinematic regions where truncation uncertainties are parametrically smaller than the signal. We incorporate the calculable dim-6$^2$ piece into the signal and cover the remaining higher-dimension uncertainty with a small set of nuisance parameters derived from a scan over Wilson-coefficient values. Our algorithm to determine the relevant nuisance parameters and distributions is automation-friendly and applies to arbitrary truncation choices. We then provide multiple examples of its implementation in high-energy collider processes focused on SMEFT truncated at $\mathcal{O}(\Lambda^{-2})$, where the dim-6$^2$ piece is used to estimate the full $\mathcal O(\Lambda^{-4})$ dependence. In the examples considered here the reduction of nuisance parameters is appreciable, generically reducing the nuisance parameter count by an order of magnitude compared to naive estimates.
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High Energy Physics (Theory)

Time-Dependent Integrability from Gauge Theory, I

Shota Komatsu, Jun-ichi Sakamoto, Anders Wallberg et al. (+1 more)

Solvable time-dependent systems provide important settings for studying non-equilibrium physics, where exact results are rare. They are also useful for benchmarking quantum simulations, which can directly probe real-time dynamics beyond the reach of conventional numerical approaches. In this paper, we show that the four-dimensional Chern-Simons theory offers a natural and unifying framework for constructing such systems. Focusing on classically integrable field theories, we consider a generalization of the four-dimensional Chern-Simons theory in which the usual holomorphic one-form is replaced by a more general, spacetime-dependent one-form. This yields a systematic procedure for generating time-dependent integrable field theories and establishes a universal relation: for every theory obtained in this way, the allowed time dependence coincides with the one-loop renormalization group flow. Despite the explicit time dependence, these theories retain Lax integrability and remain solvable by inverse scattering methods. Our construction applies to both ultralocal and non-ultralocal theories and extends previously known time-dependent sigma models to a much broader class of integrable systems. It also admits rewriting as dilaton gravity coupled to matter, producing a large family of classically integrable dilaton gravity theories in two dimensions. We also comment on connections to time-dependent integrable models studied recently in condensed matter physics and non-autonomous integrable systems arising from dimensionally-reduced Einstein gravity.
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All authors Shota Komatsu, Jun-ichi Sakamoto, Anders Wallberg, Masahito Yamazaki

High Energy Physics (Phenomenology)

Interpreting Parton Distributions with Shapley Values

Raphaël Bonnet-Guerrini, Stefano Carrazza, Stefano Forte et al. (+3 more)

We show that Shapley values can be used to trace how individual parton distributions (PDFs) shape the theory predictions for high-energy observables computed from them. This provides a tool for assessing the impact of data on PDFs when determining them, and the impact of PDF uncertainties when using the PDFs to compute collider observables. The Shapley value is computed by treating the regression of PDFs from data as a cooperative game. The PDFs are the players, and the reward is the likelihood ($\chi^2$) that characterizes the agreement between data and the predictions obtained from a given PDF, with theory and methodology held fixed. The method is agnostic to the way PDFs have been determined in the first place: for PDFs determined with a black-box AI model it may be used in order to explain the behavior of the model, and for PDFs determined using a fixed parametrization it may be used in order to expose the features and potential limitations of the parametrization. We find that the method recovers known expectations about which data constrain which PDFs in a global fit, while placing them on a more quantitative footing. We demonstrate its effectiveness in two ways. We uncover an unexpected loss of sensitivity of the gluon PDF at intermediate $x$, with potential implications for BSM searches and the gluon fusion Higgs cross section. We also show that the method can be used to improve the hyperparameter optimization procedure currently used by the NNPDF collaboration.
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All authors Raphaël Bonnet-Guerrini, Stefano Carrazza, Stefano Forte, Eva Groenendijk, Vincenzo Piuri, Ramon Winterhalder

High Energy Astrophysical Phenomena

High-Energy Neutrino Tomography of the Earth's Interior with IceCube

The IceCube Collaboration, R. Abbasi, M. Ackermann et al. (+417 more)

The Earth's interior reflects its geological evolution, from accretion to present-day dynamics. Its structure drives the geodynamo in the outer core, generating the magnetic field that shields the surface from charged cosmic radiation. The primary observables of the Earth's interior are its radial density distribution and derived quantities such as its mass and moment of inertia. These have traditionally been inferred from gravity and seismic wave propagation, which probe the macroscopic response of matter to gravitational and elastic forces. Here we instead constrain the Earth's density profile using high-energy neutrinos observed by the IceCube Neutrino Observatory at the South Pole. We analyze 10.7 years of predominantly muon-neutrino data spanning 500 GeV–100 TeV, including atmospheric neutrinos produced by cosmic-ray interactions in the Earth's atmosphere and the diffuse astrophysical neutrino flux. Neutrino attenuation depends on both the traversed column density and neutrino energy. By measuring the zenith- and energy-dependent flux suppression, we infer the Earth's radial density profile by fitting a concentric uniform-density shell model that incorporates neutrino fluxes, interaction cross sections, detector response, and glacial-ice systematic uncertainties. From the resulting density posteriors, we derive the Earth's mass and polar moment of inertia as measured by neutrinos. These are the most precise weak-interaction measurements of these quantities to date and are consistent with the Preliminary Reference Earth Model and independent gravitational determinations. Our results demonstrate that neutrinos provide a novel probe of planetary interiors via a distinct physical interaction, complementing gravity and seismology. With improved detectors and precision, neutrinos will further contribute to a multifaceted understanding of the Earth's structure.
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All authors The IceCube Collaboration, R. Abbasi, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, J.M. Alameddine, S. Ali, N. M. Amin, K. Andeen, C. Argüelles, S. Athanasiadou, S. N. Axani, R. Babu, X. Bai, A. Balagopal V., S. W. Barwick, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, P. Behrens, J. Beise, C. Bellenghi, S. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, B. Brinson, Z. Brisson-Tsavoussis, L. Brusa, R. T. Burley, D. Butterfield, K. Carloni, J. Carpio, N. Chau, Y. C. Chen, Z. Chen, D. Chirkin, S. Choi, A. Chubarov, B. A. Clark, G. H. Collin, D. A. Coloma Borja, A. Connolly, J. M. Conrad, D. F. Cowen, C. De Clercq, J. J. DeLaunay, D. Delgado, T. Delmeulle, S. Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. Díaz-Vélez, S. DiKerby, T. Ding, M. Dittmer, A. Domi, L. Draper, L. Dueser, D. Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, C. Eldridge, P. Eller, E. Ellinger, D. Elsässer, R. Engel, H. Erpenbeck, W. Esmail, S. Eulig, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. Fattorini, A. R. Fazely, A. Fedynitch, N. Feigl, C. Finley, D. Fox, A. Franckowiak, S. Fukami, P. Fürst, J. Gallagher, E. Ganster, A. Garcia, M. Garcia, E. Genton, L. Gerhardt, A. Ghadimi, C. Glaser, T. Glüsenkamp, J. G. Gonzalez, S. Goswami, A. Granados, D. Grant, S. J. Gray, S. Griffin, S. Griswold, K. M. Groth, D. Guevel, C. Günther, P. Gutjahr, C. Ha, A. Hallgren, L. Halve, F. Halzen, L. Hamacher, M. Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, J. Häußler, K. Helbing, J. Hellrung, B. Henke, L. Hennig, F. Henningsen, L. Heuermann, R. Hewett, N. Heyer, S. Hickford, A. Hidvegi, C. Hill, G. C. Hill, R. Hmaid, K. D. Hoffman, A. Hollnagel, D. Hooper, S. Hori, K. Hoshina, M. Hostert, W. Hou, M. Hrywniak, T. Huber, K. Hultqvist, K. Hymon, A. Ishihara, W. Iwakiri, M. Jacquart, S. Jain, O. Janik, M. Jansson, M. Jin, N. Kamp, D. Kang, W. Kang, A. Kappes, L. Kardum, T. Karg, A. Karle, A. Katil, M. Kauer, J. L. Kelley, M. Khanal, A. Khatee Zathul, A. Kheirandish, T. Kim, H. Kimku, F. Kirchner, J. Kiryluk, C. Klein, S. R. Klein, Y. Kobayashi, S. Koch, A. Kochocki, R. Koirala, H. Kolanoski, T. Kontrimas, L. Köpke, C. Kopper, D. J. Koskinen, P. Koundal, M. Kowalski, T. Kozynets, A. Kravka, N. Krieger, T. Krishnan, K. Kruiswijk, E. Krupczak, E. Kun, N. Kurahashi, C. Lagunas Gualda, L. Lallement Arnaud, M. J. Larson, F. Lauber, J. P. Lazar, K. Leonard DeHolton, A. Leszczyńska, C. Li, J. Liao, C. Lin, Q. R. Liu, Y. T. Liu, M. Liubarska, C. Love, L. Lu, F. Lucarelli, W. Luszczak, Y. Lyu, M. Macdonald, E. Magnus, Y. Makino, E. Manao, S. Mancina, A. Mand, I. C. Mariş, S. Marka, Z. Marka, L. Marten, I. Martinez-Soler, R. Maruyama, J. Mauro, F. Mayhew, F. McNally, K. Meagher, A. Medina, M. Meier, Y. Merckx, L. Merten, S. Minji, J. Mitchell, L. Molchany, S. Mondal, T. Montaruli, R. W. Moore, Y. Morii, A. Mosbrugger, D. Mousadi, E. Moyaux, T. Mukherjee, M. Nakos, U. Naumann, R. Neshat, L. Neste, M. Neumann, H. Niederhausen, M. U. Nisa, K. Noda, A. Noell, A. Novikov, A. Obertacke, V. O'Dell, A. Olivas, R. Orsoe, J. Osborn, E. O'Sullivan, B. Owens, V. Palusova, H. Pandya, A. Parenti, C. Parisel, N. Park, V. Parrish, E. N. Paudel, L. Paul, C. Pérez de los Heros, T. Pernice, T. C. Petersen, J. Peterson, S. Pick, M. Plum, A. Pontén, V. Poojyam, B. Pries, R. Procter-Murphy, G. T. Przybylski, L. Pyras, C. Raab, J. Rack-Helleis, N. Rad, M. Ravn, K. Rawlins, Z. Rechav, A. Rehman, I. Reistroffer, E. Resconi, C. D. Rho, W. Rhode, L. Ricca, B. Riedel, A. Rifaie, E. J. Roberts, S. Rodan, M. Rongen, A. Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, J. Saffer, D. Salazar-Gallegos, P. Sampathkumar, A. Sandrock, G. Sanger-Johnson, M. Santander, S. Sarkar, M. Scarnera, M. Schaufel, H. Schieler, S. Schindler, L. Schlickmann, B. Schlüter, F. Schlüter, N. Schmeisser, T. Schmidt, A. Scholz, F. G. Schröder, S. Schwirn, S. Sclafani, D. Seckel, L. Seen, M. Seikh, S. Seunarine, P. A. Sevle Myhr, R. Shah, S. Shah, S. Shefali, N. Shimizu, B. Skrzypek, R. Snihur, J. Soedingrekso, D. Soldin, P. Soldin, G. Sommani, D. Song, C. Spannfellner, G. M. Spiczak, C. Spiering, J. Stachurska, M. Stamatikos, T. Stanev, T. Stezelberger, T. Stürwald, T. Stuttard, G. W. Sullivan, I. Taboada, S. Ter-Antonyan, A. Terliuk, A. Thakuri, M. Thiesmeyer, W. G. Thompson, J. Thwaites, S. Tilav, K. Tollefson, J. A. Torres, S. Toscano, D. Tosi, K. Upshaw, A. Vaidyanathan, N. Valtonen-Mattila, J. Valverde, J. Vandenbroucke, T. Van Eeden, N. van Eijndhoven, L. Van Rootselaar, J. van Santen, J. Vara, F. Varsi, M. Velazquez, M. Venugopal, M. Vereecken, S. Vergara Carrasco, S. Verpoest, D. Veske, A. Vijai, J. Villarreal, C. Walck, A. Wang, E. H. S. Warrick, C. Weaver, P. Weigel, A. Weindl, J. Weldert, A. Y. Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, L. Witthaus, G. Wrede, X. W. Xu, J. P. Yanez, Y. Yao, E. Yildizci, S. Yoshida, F. Yu, S. Yu, T. Yuan, S. Yun-Cárcamo, A. Zander Jurowitzki, A. Zegarelli, S. Zhang, Z. Zhang, P. Zhelnin, P. Zilberman, C. Zilleruelo Cañas

High Energy Astrophysical Phenomena

A Shock-based Interpretation of Radio and X-ray Emission in Active Galactic Nuclei

Fan Wu and Benzhong Dai

We propose a shock-based framework to interpret the radio and X-ray emission in active galactic nuclei (AGNs), whose origin remains an open problem. In this framework, the radio emission is produced by synchrotron radiation in the accretion flow or a jet/weak outflow, while the dominant X-ray component depends on the accretion state, the location of the non-thermal emission region, and the available seed photon field. The model provides a self-consistent interpretation of radio and X-ray emission in typical non-jetted AGNs, including low-luminosity AGNs, Seyfert galaxies, and radio-quiet quasars. In jetted AGNs, our results disfavor scenarios in which the non-thermal electrons responsible for X-ray emission are accelerated in the disk or the corona. We use two widely discussed empirical diagnostics, radio loudness and the fundamental plane (FP) of black hole (BH) activity, to assess the applicability and limitations of the model. It can naturally explain the observed trends that the radio loudness increases with BH mass and decreases with the Eddington ratio. The observed slope of the FP depends on how the key physical quantities scale with the accretion rate. As the accretion rate increases, the advection-dominated accretion flow region contracts while the thin disk region expands, reflecting a transition toward a more radiatively efficient accretion structure. The Eddington ratio therefore influences the accretion structure, and may in turn shape the observed AGN classes.
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Plasma Physics

RF Helicon Plasma Thruster for an Atmosphere-Breathing Electric Propulsion System (ABEP)

Francesco Romano

This dissertation focuses on Atmosphere-Breathing Electric Propulsion (ABEP) for propellant-less continuous orbiting in very low Earth orbits (VLEO) and very low Mars orbits (VLMO). ABEP utilizes an intake to collect atmospheric particles as propellant for an electric thruster, offsetting aerodynamic drag. An analytical system-level analysis assesses collectible mass flow, drag, and power requirements, using GOCE as a case study. Three intake designs are developed based on gas-surface interactions. Two diffuse-reflection designs yield collection efficiencies $\eta_c < 0.5$, while a specular-reflection design achieves $\eta_c < 0.95$. The specular intake demonstrates superior robustness against flow misalignment, maintaining high efficiency at large angles. The proposed ABEP thruster features a contactless, neutralizer-free design using a helicon plasma discharge, preventing erosion from aggressive species like atomic oxygen. Numerical simulations via the HELIC code determined key design parameters (frequency, magnetic field, plasma density), leading to the implementation of a resonant birdcage antenna with high electrical efficiency. The thruster was manufactured and experimentally validated using Ar, N_2, and O_2. Tests demonstrated successful ignition and operation across relevant mass flows with low power consumption ($P_f < 60$ W). Additionally, a B-dot probe was developed to detect helicon waves in the plasma plume. Ultimately, this work delivers verified intake designs and a novel contactless plasma thruster with high electrical efficiency (>99% in vacuum). Both components represent promising technologies for near-future ABEP applications. Future development outlooks, diagnostics, and spacecraft configurations are also discussed.
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General Relativity and Quantum Cosmology

Observational Constraints on Kazakov-Solodukhin Quantum-Deformed Black Holes from M87$^*$ and Sgr A$^*$ Shadows

A. Errehymy, Y. Khedif, M. Daoud et al. (+4 more)

We explore the Kazakov-Solodukhin quantum-deformed black hole spacetime, characterized by a single deformation parameter \( \eta \) that encodes quantum corrections to the classical Schwarzschild solution. The model preserves the correct general-relativistic limit as \( \eta \to 0 \), while introducing significant and physically meaningful deviations in the strong-field regime. A central and remarkable feature of the geometry is the regularization of the classical singularity: curvature invariants remain finite near the minimal radius \( r = \eta \), effectively replacing the divergent core with a smooth and well-behaved region. This behavior naturally introduces a minimal length scale into the spacetime structure, offering a geometrically motivated resolution of the singularity problem. The deformation modifies the horizon structure, shifts the event horizon location, and alters the mass-radius relation. It also reduces the surface gravity, leading to a lower Hawking temperature and a slower evaporation process, thereby enhancing the thermodynamic stability of the black hole. Photon dynamics are correspondingly affected, resulting in a displaced photon sphere and modified strong-lensing characteristics. While the shadow remains perfectly circular due to spherical symmetry, its size depends sensitively on \( \eta \). Observational constraints can be expressed through \( \left| R_{sh}(\eta) - R_{obs} \right| \leq \Delta R_{obs}, \) which places an upper bound on the deformation parameter. In the weak-field limit, the deflection angle acquires a quadratic correction proportional to \( \eta^2 \), ensuring consistency with precision tests while allowing potentially detectable deviations in strong-gravity observations. These features make the model both theoretically appealing and observationally testable.
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All authors A. Errehymy, Y. Khedif, M. Daoud, B. Turimov, S. Usanov, Z. Yasakov, Z. Avezmuratova

Materials Science

High-Entropy Nitride Photocatalysts for Visible-Light Antibiotic Degradation: Structural Stability, In Situ Interfacial Visualization, and Molecular-Level Mechanistic Insights

Zahoor Manzoor, Shamik Chowdhury, Raphael Benjamim de Oliveira et al. (+5 more)

High-entropy nitrides (HENs) have emerged as a promising class of advanced materials with tunable electronic structures, high stability, and abundant active sites. The incorporation of nitrogen enhances visible-light absorption, promotes efficient charge separation, and improves structural robustness, making these materials highly suitable for photocatalytic applications. In this study, (MnFeCoNiCu)N-based HEN nanoparticles (NPs) were synthesized as visible-light-assisted photocatalysts for the degradation of antibiotics, including sulfamethoxazole (SME) and tetracycline (TCL). The catalyst exhibited excellent performance, achieving 96% degradation of SME and 94% removal of TCL within 2 h of visible-light irradiation. The photocatalytic activity was systematically evaluated under varying operational parameters, including solution pH, catalyst dosage, pollutant concentration, and the presence of coexisting ions. Notably, the catalyst maintained high efficiency in real water matrices, demonstrating its practical applicability. The entropy-stabilized nitride framework exhibited negligible metal leaching, excellent thermal and structural stability as confirmed by temperature-dependent synchrotron angle-dispersive X-ray diffraction, and stable performance over multiple reuse cycles. Furthermore, in situ liquid-cell transmission electron microscopy provided real-time insight into catalyst-pollutant interactions, while complementary molecular simulations revealed the structural stability of the HEN NPs during molecular adsorption and the distinct interaction modes of the two antibiotics. Phytotoxicity tests using Vigna radiata confirmed the effective detoxification of treated solutions. Overall, this work establishes (MnFeCoNiCu)N HENs as efficient and durable visible-light-driven photocatalysts for the removal of antibiotics from complex aqueous environments.
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All authors Zahoor Manzoor, Shamik Chowdhury, Raphael Benjamim de Oliveira, Marcelo Lopes Pereira Junior, Guilherme da Silva Lopes Fabris, Prikshat Dadhwal, Douglas S. Galvao, Chandra Sekhar Tiwary

Quantum Physics

Krylov-Lie Algebras for Variational Quantum Algorithms: Geometric, Depth-Aware Insights into Expressivity and Trainability

Anžej Margeta-Cacace

Variational quantum algorithms (VQAs) are a leading approach to near-term quantum computation, but their utility is limited by barren plateaus and other pathologies in their loss landscapes. Existing landscape theories based on dynamical Lie algebras, Jordan-algebraic Wishart systems, approximate t-designs, and Haar-random circuits are foundational, but they often neglect the finite-depth geometry of realistic ansätze and are therefore ill-suited to the shallow-depth regime, where VQAs are poor approximators of 2-designs and trainability is most feasible. This work introduces Krylov algebras, algebraic structures induced by the Krylov span of a finite generator set acting on one or more seed vectors, as a framework for VQA landscape theory. We show that VQA reachable manifolds can be approximated in a numerically robust, geometrically faithful fashion by Krylov-Lie algebras and groups, and that these structures induce canonical invariant measures for computing expectation values and variances under general sampling measures. In particular, we derive weighted non-Haar variance formulas that recover the usual Lie-algebraic Haar formulas as a special case while isolating non-Haar effects into explicit correction terms. We also show that the common heuristic that sufficiently deep circuit ensembles must converge to Haar fails in general without additional hypotheses, identify concrete obstructions to naive Haar convergence, and recover convergence under natural necessary and sufficient ergodic conditions. Lastly, our formulas further imply that non-Haar contributions to landscape statistics may mitigate barren plateaus by reweighting the visible sectors of the loss landscape, suggesting that VQAs may be more trainable than recent literature has posited.
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Physics Education

Viscosity of cooking oil: From kitchen to classroom

Endre Joachim Lerheim Mossige

This paper presents a fun and relatable classroom experiment to measure the viscosity of cooking oil using household tools and ingredients like kitchen scales, mugs, and dried peas. The experiment requires no formal training in math or physics, and helps to build intuition about friction, Newton's laws of motion, and Archimedes' buoyancy law.
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Quantum Physics

COMET: Combinatorial Optimization for Multiplex Editing Targets Via Constraint-Preserving QAOA

Priyansh Singhal, Sumit Maheshwari and Piyush Joshi

Multiplex CRISPR-Cas9 gene editing requires selecting one guide RNA per target gene subject to cross-gene interactions: a constrained combinatorial problem that can be formulated as a Quadratic Unconstrained Binary Optimization (QUBO) and solved via the Quantum Approximate Optimization Algorithm (QAOA). The one-hot per-gene constraint is conventionally enforced by adding quadratic penalty terms to the cost Hamiltonian, but penalty coefficient selection is heuristic and penalties amplify hardware noise. An alternative is to enforce the constraint structurally via the XY-mixer, which preserves feasibility by construction. We present COMET, a systematic comparison of penalty-based and XY-mixer QAOA on a three-gene, twelve-qubit multiplex editing instance targeting the immune-checkpoint genes PDCD1, LAG3, and HAVCR2. In simulation, the XY-mixer exceeds 95% probability of the optimum by QAOA depth p=3, while three penalty variants spanning an order of magnitude in penalty coefficient remain below 6% at every depth. On IBM's ibm_kingston (Heron r2) processor, the XY-mixer's simulator-hardware energy gap stays within |0.8| across all depths, while the worst-tuned penalty variant's gap reaches +53.9. We provide an honest account of where the structural guarantee partially breaks under gate-level noise. The twelve-qubit instance is classically trivial; our contribution is a methodological comparison of constraint-enforcement strategies in a biologically motivated domain, with real-hardware validation.
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Quantum Physics

Comparing the Performance of Leading VQE Algorithms for Computing Ground-State Energies of Amino Acids

Sanskriti Shindadkar, Clyde Villacrusis, Jasper Andrews et al. (+1 more)

Simulating molecules is a major application of quantum computing, with the potential to overcome exponential scaling constraints of classical computation. Researchers use different methods in order to evaluate the readiness of NISQ computers in order to test current simulation capabilities. We present an integrated repository with reproducible benchmarks of over 10 different ansatzes from published papers and two different truncation methods, applicable to any set of mapped hamiltonians, providing a single pipeline for comparing performance along multiple axes, including variance and computational time, among others. We apply them to simulate different amino acids, using hamiltonians taken from the QMProt Dataset. We then ran four separate experiments. First, we quantified noise resilience by optimizing the same hardware-efficient ansatzes under identical initialization while sweeping PennyLane noise channels and strengths, and measuring parameter drift, cosine similarity of optimal parameters, and energies evaluated on noiseless versus noisy backends. We then studied barren-plateau-related trainability via gradient-variance diagnostics and optimization trajectories across initialization strategies and ansatzes depth on small systems. We then compared adaptive versus fixed ansatzes at matched parameter budgets, reporting outer-loop iterations, wall time, and especially total cost-function evaluations to fairly contrast greedy adaptive growth with layered hardware-efficient circuits. Lastly, we mapped accuracy versus expressive capacity by sweeping the number of retained adaptive operators and recording ground-state energy error relative to classical references.
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All authors Sanskriti Shindadkar, Clyde Villacrusis, Jasper Andrews, Brandon Yan