Strongly Correlated Electrons
From Dirac Cones to Semions: An Exact Finite-Size Theory of Parity-Anomaly Transport in Chiral Spin Liquids
Kumar Ghosh
Chiral spin liquids realize a topological state whose universal response is a fractional
spin Hall conductance $\nu_s$. The three quantities that determine this response, the integer Chern number of the fractionalized spinons, the level of the emergent Chern–Simons gauge field, and the physically measured
spin pump, are related but distinct, and their relation is often stated only schematically. Here we derive it from a single object: the parity-odd determinant of a gapped Dirac cone on a spatial cylinder, resummed exactly to all orders in the compact holonomy. This determinant fixes the map from spinon
topology to measurable response, and proves that finite-size corrections to the topological pump are strictly exponential, with no universal $1/L$ term. We test the resulting predictions on the kagome
chiral spin liquid at three independent levels: the exact one-loop field theory, a parton band-structure calculation ($C=-1$, converging exponentially over cylinders four to twelve sites wide), and an interacting density-
matrix renormalization group flux pump on the explicitly
chiral $J$–$J_\chi$
Hamiltonian ($\nu_s=-0.500\pm0.011$). All three agree with the analytic prediction without adjustable parameters, providing a fully quantitative bridge between microscopic
topology and observable fractional response.
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High Energy Physics (Phenomenology)
Electron stability constrains neutrino time delays
Mauricio Bustamante, José Manuel Carmona, José Luis Cortés et al. (+2 more)
Superluminal
neutrino propagation, induced by Lorentz-invariance violation (LIV), is strongly constrained by
vacuum pair emission, $\nu \to \nu + e^- + e^+$, a process ordinarily forbidden, which rapidly degrades the energy of high-energy
neutrinos. Consequently, observable
neutrino time delays are often preferentially associated with subluminal propagation, prompting LIV interpretations of claimed time delays between high-energy
cosmic neutrinos and gamma rays. However, this expectation is at odds with the observed stability of high-energy electrons. The same Lorentz-violating correction associated with subluminal
neutrino propagation opens the overlooked complementary decay channel $e^- \to e^- + \nu + \bar{\nu}$, leading to electron instability. We derive constraints on LIV from recent observations of TeV–PeV astrophysical electrons. These electron stability limits rule out LIV invoked to explain delays of high-energy
cosmic neutrinos. Consequently,
neutrino time delays are constrained on both the superluminal and subluminal sides. Therefore, observable delays require either purely astrophysical origins, a realization of LIV that affects all particle species equally, or physics beyond the standard effective-field-theory framework.
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All authors Mauricio Bustamante, José Manuel Carmona, José Luis Cortés, Ardit Gkioni, Maykoll A. Reyes
Astrophysics of Galaxies
IRIS: Deciphering Spectral-Line Imagery of the Galactic Center by Machine-Learning on Simulations
B. L. DuBois, Cara Battersby, Jonah C. Baade et al. (+11 more)
In understanding the 3D structure of the Milky Way's Central Molecular Zone (CMZ), we are limited by our edge-on perspective. Towards addressing this problem, we introduce Imagery Reversion Informed by Simulation (IRIS). IRIS is a novel machine-learning code base featuring a deep convolutional neural network (CNN), which we have designed to translate edge-on observations of our Milky Way
Galaxy into top-down images by training on data generated from AREPO
galaxy simulations and synthetic observations of those simulations. We develop a large custom
dataset on which we train our bespoke model, and then test the trained model on synthetic data to probe the potential of this machine-learning method, which we call supervised reversion. We then apply our trained model to real observations from the SEDIGISM 13CO(2-1) survey, yielding new top-down views of our CMZ. Though our SEDIGISM reversions are not fully consistent across model training runs, we posit that this lack of convergence can be alleviated by expansion of the training
dataset. We argue that these results represent a strong proof-of-concept for the use of supervised reversion to decipher our CMZ's 3D structure. Crucial in generating our training
dataset's 100k synthetic observations, we introduce IRIS Synthetic Observation (IRIS-SO), a new GPU-accelerated and fully differentiable code implemented in PyTorch for the non-LTE synthetic observation of spectral lines and
dust. We find that IRIS-SO provides up to 10,000x speedups in comparison to the synthetic-observation code RADMC-3D. We release all the IRIS code open-source at https://github.com/bldubois/IRIS.
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All authors B. L. DuBois, Cara Battersby, Jonah C. Baade, Dani R. Lipman, H Perry Hatchfield, Jack Sullivan, Russell Bentley, Stefan Reissl, Ralf S. Klessen, Victor F. Ksoll, Mattia C. Sormani, Zi-Xuan Feng, Adam Ginsburg, Robin Tress
High Energy Astrophysical Phenomena
A possible high-redshift origin for the short GRB 061201: implications of a compact binary merger beyond cosmic noon
E. Troja, B. O'Connor, Y.-H. Yang et al. (+4 more)
Short gamma-ray bursts (GRBs) at
redshift z>2 remain exceptionally rare, yet they are crucial for tracing compact binary mergers in the early Universe and understanding their role in the production of r-process elements. GRB 061201 is an unusual and still debated event: although its optical afterglow was accurately localized, no secure coincident host
galaxy was identified, and the proposed associations with nearby
galaxies all require a large separation between the GRB and its birth site. In this work, we revisit GRB 061201 and argue that the observations are more naturally explained if the burst occurred within a faint F322W2~28.4 AB mag
galaxy at z>2. By combining constraints from the afterglow and deep near-infrared imaging from JWST, we show that a distant origin provides a coherent explanation of the burst phenomenology. If confirmed, GRB 061201 would represent one of the most distant short GRBs known, extending the observed compact merger population to an epoch when the Universe was only about two billion years old.
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All authors E. Troja, B. O'Connor, Y.-H. Yang, T. M. Gaudin, M. Yadav, N. Passaleva, S. Dichiara
Quantum Physics
Mechanistic Interpretability and Causal Feature Steering of Neural Quantum States via Sparse Autoencoders
Zihao Qi and Christopher Earls
Neural
Quantum States (NQS) are a remarkably expressive class of variational ansätze for
quantum many-body wavefunctions, yet little is understood about their internal mechanisms: trained on variational objectives alone, how do NQS accurately capture physical observables that they have never been explicitly optimized for? In this work, we present a systematic approach to analyze the internal activations of NQS using sparse autoencoders. We extract features from the residual stream and demonstrate that these features strongly correlate with physical observables such as order parameters, staggered magnetization, and half-chain correlators, across both ground state representation and real-time dynamics. Remarkably, the discovery of these features is entirely unsupervised, with no physical labels provided. We further establish that such features causally affect the corresponding observables predicted by NQS, by showing that targeted, post-training intervention on a single feature smoothly and monotonically steers the corresponding observable, while leaving the variational energy nearly unchanged. These results demonstrate that NQS are not merely functional approximators, but encode rich, interpretable internal representations of physical information. Our approach provides both a diagnostic and an intervention tool for NQS, and serves as a foundation for using mechanistic interpretability towards more reliable, transparent NQS.
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Quantum Physics
Mohammad Jafari and Fernando Iemini
We investigate the
entanglement dynamics along
quantum trajectories during the seeding of time-crystalline order in a boundary time
crystal (BTC). Specifically, how
entanglement spreads among different
spin ensembles when a BTC attempts to seed its time-crystalline behavior onto otherwise static
spin ensembles, through a collective dissipative channel. We analyse both the dynamical growth of
entanglement in time and the steady-state properties of the system. Our results reveal two fundamentally distinct regimes. In the seeded BTC phase, the steady-state
entanglement entropy between the ensembles grows with system size $N$, accompanied by macroscopic fluctuations along the trajectories. In contrast, in the non-seeded static phase, both the steady-state
entanglement and its fluctuations decay exponentially with $N$. The model thus features a measurement-induced phase transition (MIPT) driven by the seeding mechanism. Furthermore, these findings establish dissipative seeding as a powerful mechanism for controlling
quantum correlations in open many-body systems, with direct experimental relevance to this class of model without a postselection barrier.
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Quantum Physics
Decoupling band topology from criticality in bosonic systems
Mariam Ughrelidze, Lorenza Viola and Emilio Cobanera
A new understanding of criticality in systems described by quadratic bosonic
Hamiltonians (QBHs) ties the emergence of long-range correlations to boundaries of dynamical, not thermodynamical, stability in parameter space. This separation occurs because the solution of the Heisenberg equations of motion is determined by an auxiliary pseudo-Hermitian dynamical system. The boundary points of a region of dynamical stability can be either exceptional points, generically associated with long-range correlations, or Krein collisions, where correlations can be either long- or short-range. We investigate the interplay of this landscape of possibilities with band
topology and boundary physics, by relying on both specific examples and general arguments. The examples stem from a two-parameter, thermodynamically unstable family of QBHs obtained from the bosonic Su-Schrieffer-Heeger model by breaking particle conservation while preserving a
chiral pseudo-
symmetry. As a function of an interpolation parameter, distinct regions emerge within a fixed dynamical-stability phase, which prove to be topologically trivial and nontrivial, respectively. The topological phase transition is a line of Krein collisions, which coincides with the closing of a band gap at zero and causes the localization length of the topologically mandated boundary zero modes to diverge before disappearing. We show that the
chiral pseudo-
symmetry induces, despite the broken particle-number
symmetry, enough structure on its associated dynamical
matrices to support a topological classification and a bulk-boundary correspondence, independently of dynamical stability. This strongly suggests that, for non-interacting
bosons, topological physics extracted from basic index theory is insensitive to dynamical stability and, a posteriori, criticality.
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High Energy Physics (Phenomenology)
Axion Misalignment Across First-Order Phase Transitions
Galymzhan Baltabay, Francesco D'Eramo and Ville Vaskonen
When the
axion mass is generated during a first-order phase transition and becomes non-vanishing only inside expanding true-
vacuum bubbles, the standard picture of misalignment production is qualitatively modified. Using
lattice simulations in an expanding universe, we study dark matter production within such a framework and identify two distinct regimes. For rapid transitions, the onset of oscillations is delayed until bubble percolation, enhancing the relic abundance. For slower transitions, spatial gradients generated by expanding bubbles suppress the effective misalignment angle through the bubble misalignment mechanism. We derive a semi-analytical expression for the relic density that provides a unified description of both regimes and accurately reproduces the simulation results. Finally, we show how this mechanism also modifies isocurvature perturbations and the small-scale matter power spectrum, with important implications for
axion minicluster formation.
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Quantum Physics
Controlling Waiting Time Statistics in Monitored Collective Spins: Mitigating Detector's Resolution Barrier in Measurement-Induced Phase Transitions
Tanbir Islam and Fernando Iemini
In collective dissipative
spin systems, the postselection barrier can be partially mitigated; however, a further obstacle may be posed by the finite temporal resolution of detectors. In this work, we investigate how initial-state inhomogeneities can control waiting-time statistics between
quantum jumps, thereby mitigating the detector-resolution problem. We consider a collectively monitored
spin model with a boundary time-crystalline phase, introducing inhomogeneity by partitioning the ensemble into two subsystems rotated by an angle $\theta$. We find that the measurement-induced phase transition survives under inhomogeneities, with different
entanglement scaling regimes. The waiting time increases with $\theta$, scaling as $1/N$ but with a prefactor strongly enhanced by orders of magnitude, and in the anti-aligned limit $\theta = \pi$ it remains finite, fully resolving the resolution barrier. This mitigation, however, comes at a cost: the
entanglement saturation time becomes significantly longer, partially reintroducing the postselection barrier. Our results highlight a trade-off between detector resolution and postselection overhead, with direct implications for the experimental observation of measurement-induced phenomena.
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Astrophysics of Galaxies
The fingerprint of primordial mass segregation on the tidal tails of star clusters
S. Mojtaba Ghasemi, Hosein Haghi, Mohammad Mansoury et al. (+3 more)
We investigate the effect of
primordial mass segregation (PMS) in shaping the
tidal tail structures of
star clusters, searching for any trace of PMS on the tails at both early and late evolutionary stages. Through N-body simulations, we analyze clusters with two different degrees of PMS at various Galactocentric distances (R_G), considering two black hole retention scenarios. Our findings reveal that PMS influences early cluster expansion and the formation of
tidal tails with a bottom-heavy
stellar mass function, this being more pronounced at smaller R_G but diminishes over time. Primordially segregated clusters exhibit denser, unified, and longer tail structures compared to non-segregated clusters. The mean
stellar mass distribution along the tails shows distinct patterns for primordially segregated and non-segregated clusters, converging at later evolutionary stages. The retention of
stellar remnants has a weak impact on the mean mass distribution along the tails and on its morphology. We find that although mean mass differences persist along the
tidal tails, the rate of change in primordially mass-segregated clusters eventually converges with that of non-segregated clusters, suggesting that the influence of
primordial mass segregation on the
tidal tails gradually diminishes over the course of cluster
evolution.
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All authors S. Mojtaba Ghasemi, Hosein Haghi, Mohammad Mansoury, Akram Hasani Zonoozi, Pouriya Miri, Pavel Kroupa
Astrophysics of Galaxies
Extreme outflow velocities and weak UV emission lines indicate quasars shedding their dust cocoons
Guozhen Ma, Stefan J. Geier, Johan P. U. Fynbo et al. (+11 more)
The recently discovered low-ionisation broad absorption line (LoBAL)
quasar GQ 1309$+$2904 is unusual due to its very broad, highly blueshifted absorption troughs and an absence of broad emission lines except for ${\mathrm{H} \alpha}$. In this paper, we present observations of six
quasars that appear very similar to GQ 1309$+$2904 in the rest-frame ultraviolet (UV). We measure the systemic
redshifts of these
quasars to be $z\approx$ 2.07–3.28 from detected ${\mathrm{H} \alpha}$ emission lines. We confirm that all targets are
quasars with highly blueshifted BALs possessing high-speed
outflows with velocities up to $\sim 0.16\,c$, and five of them are confidently identified as LoBAL
quasars. Based on ${\mathrm{H} \alpha}$ emission, black hole masses and Eddington ratios of these
quasars are $M_{\mathrm{BH}} \approx 10^{8.7}$–$10^{9.4}\,M_{\odot}$ and $L_{\mathrm{bol}} / L_{\mathrm{Edd}} \approx$ 0.14–0.34, indicating that their central black holes are very massive and active. Every
quasar in our sample exhibits a very flat or reddened continuum. The spectral shapes of three objects are well-fitted by a normal
quasar composite reddened by a Small-Magellanic-Cloud-like (SMC-like) extinction curve, while the other three require a steeper extinction law. Broad-band ($BVR$) polarimetry for two of the latter group (plus GQ 1309$+$2904) reveals their low polarisations, consistent with low inclination (more face-on) angles. We propose that these objects are weak emission-line
quasars (WLQs) observed through the disc wind, caught emerging from their
dust cocoons. As
quasars shed their cocoons,
dust grains in the disc wind are shattered into smaller particles, producing the UV-steeper extinction curve observed along the
outflow. We present a schematic illustration of this shedding process that can account for the peculiar spectral features observed in our sample.
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All authors Guozhen Ma, Stefan J. Geier, Johan P. U. Fynbo, Lise Christensen, Andrei Berdyugin, Rasmus Frederiksen, Kasper E. Heintz, Phillip D. Henriksen, Jens-Kristian Krogager, Cédric Ledoux, Vilppu Piirola, Palle Møller, Simone Vejlgaard, Hyunseop Choi
Quantum Physics
Ravines in quantum cost landscapes: opportunities for improved VQA predictions
Felix J. Beckmann and João F. Bravo
The
geometric and topological structure of
quantum cost landscapes (QCLs) governs the optimization and thus the predictive power of variational
quantum algorithms (VQAs). We systematically analyze ravines - low-cost paths connecting local minima - using an adapted version of the nudged elastic band (NEB)
algorithm, a method originating from theoretical chemistry. By training
quantum neural networks (QNNs) to classify the concentratable
entanglement of
quantum states, we apply the NEB
algorithm and numerically identify ravine structures in QCLs of hardware-efficient ansatzes. Beyond visualizing these ravines, we construct an ensemble prediction framework by averaging predictions from QNNs parameterized along the low-cost NEB path. We introduce a resource-light pre-training metric which quantifies local-prediction variability and serves as a strong performance indicator for VQAs, even beyond the scope of this study. When base classifiers are drawn from
circuit and weight initializations exhibiting high local-prediction variability, the
quantum-based NEB ensembles outperform both classical and naive
quantum alternatives. Moreover, a complexity analysis shows that leveraging the ravine-like structure of QCLs with the QNN NEB approach substantially reduces computational costs compared to naive QNN ensembling. A depth and
qubit scaling analysis indicates that ravines persist across both scalings, and that, despite the expected growth in resource requirements with the
qubit scaling, the NEB approach also accelerates convergence over the naive alternative.
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High Energy Physics (Theory)
Quark Anti-Quark Fusion and Walking RG Flows
Filipp Chernikov, Nikolay Gromov and Amit Sever
We study the fusion of two conjugate conformal line defects on the sphere. At small separation, their spectrum is governed by a universal Fusion Master Equation. Below a critical coupling, the fused defect has two conformal fixed points; at criticality, they collide and move into the complex plane, producing walking RG behaviour. Although individual energy levels then drift with the UV scale and are scheme dependent, the $SL(2,\mathbb{R})$ Casimir continues to commute with the
Hamiltonian below that scale. This organises the spectrum into conformal families and fixes a universal, scheme-independent density of states. We derive this structure in the planar ladder model and obtain an exact finite-coupling description of conjugate $1/2$-BPS Wilson-line fusion in planar ${\cal N}=4$ SYM using the
Quantum Spectral Curve. We test our results against perturbation theory and semiclassical string theory.
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High Energy Physics (Theory)
Algorithmic Dualization of Unitary Circular Quivers
Riccardo Comi, Chiung Hwang and Fabio Marino
We introduce a field-theoretic
algorithm to find the $SL(2,\mathbb{Z})$ duality web of 3d $\mathcal{N}=4$ circular quiver theories with
unitary gauge groups, extending the
algorithm for linear quivers. Although circular and linear quivers share the same local structure, the circular
topology requires additional ingredients, which we formulate in terms of topological and baryonic QFT blocks, together with new $SL(2,\mathbb{Z})$ duality moves acting on them. For good circular quivers, this provides a field-theoretic derivation of mirror
symmetry and extends it to the full $SL(2,\mathbb{Z})$ duality web. We then study bad circular quivers, distinguishing between local badness, associated with under-balanced gauge nodes, and global badness, arising from the circular
topology itself. In particular, we analyze the
magnetic and electric dual frames of globally bad circular quivers and provide additional evidence for the proposed duality by matching the
Higgs branch index with the dual Coulomb branch index. The latter exhibits a structure reminiscent of permutation-group gauging and reveals a refined relation to the ADHM quiver, flowing to the $\mathcal{N}=8$ infrared fixed point.
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Quantum Physics
One-Body Purity, Non-Gaussianity, and Entanglement in Interacting Integrable Models
Rafał Świętek, Maksymilian Kliczkowski, Lev Vidmar et al. (+1 more)
When describing
entanglement in typical midspectrum eigenstates of many-body
lattice Hamiltonians, two paradigms have emerged that capture the behavior observed in integrable and nonintegrable systems, Haar-random fermionic Gaussian states and Haar-random pure states, respectively. Remarkably, the former capture the behavior of interacting integrable systems, whose eigenstates are non-Gaussian. We argue that the paradigm that captures both the
entanglement properties and the lack of Gaussianity in integrable systems is that of random superpositions of polynomially many Gaussian states. In contrast, eigenstates of nonintegrable systems are consistent with being described by random superpositions of exponentially many Gaussian states. We gain this understanding by comparing analytical and numerical results for the one-body purity, the non-Gaussianity, and the
entanglement entropy of the random superpositions and the
Hamiltonian eigenstates.
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All authors Rafał Świętek, Maksymilian Kliczkowski, Lev Vidmar, Marcos Rigol
Instrumentation and Methods for Astrophysics
TEQUILA: Mechanism-free polarimetry for astronomy
Alan M. Watson and Noémie Globus
TEQUILA (Transient Event $Q$, $U$, and $I$ Light Analyzer) is an optical imaging polarimeter developed for the second Nasmyth port of the 1.3-m COLIBRÍ altitude-azimuth
telescope at Observatorio Astronómico Nacional in San Pedro Mártir, México (OAN-SPM). TEQUILA uses a CMOS sensor with an on-chip wire-grid micro-polarizer array to obtain simultaneous, single-exposure measurements of the Stokes parameters $I$, $Q$, and $U$ without moving optical components. This mechanism-free instrument, built entirely from commercial components, delivers seeing-limited imaging in a fixed optical band and is optimized for early-time follow-up of transient sources, including gamma-ray burst afterglows, blazars, and variable young
stellar objects. In this paper, we describe the scientific motivation, the instrument design and implementation, the calibration, and initial science results. Sensor characterization reveals a polarimetric structure in the flat field and a low
quantum efficiency, which we estimate to be approximately 17%, including losses introduced by the micro-polarizer array. For point sources, TEQUILA achieves absolute polarimetry with RMS uncertainties of 0.15% in pupil-tracking observations and 0.20% in field-tracking observations. In pupil-tracking mode, the observed RMS is fully explained by the measurement and standard-
star uncertainties, with no evidence for an additional calibration term. In contrast, field-tracking observations require an additional calibration uncertainty of approximately 0.10%. Calibration for resolved-source polarimetry remains in progress.
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Quantum Physics
Integrated Dual-Resonator Architecture for Telecom Photon-Memory Entanglement
Alexander Kolar, Ian Chin, Conner Fong et al. (+5 more)
Scalable
quantum networks require the efficient generation and storage of
entanglement between photonic
qubits and
quantum memories.
Quantum repeaters based on absorptive rare-earth-ion photonic
memories offer a promising route toward highly multiplexed
quantum networking, but unifying spectrally matched
photon sources and
quantum memories within a common architecture remains a major challenge. Here we demonstrate an integrated photonic architecture for telecom
photon-
memory entanglement generation based on dual self-similar silicon carbide microring resonators. Connected by a fiber link, one resonator operates as an entangled
photon-pair source, while the other functions as a cavity-enhanced atomic-frequency-comb
quantum memory. The
memory resonator reaches an ensemble cooperativity of 1.9 after hyperfine initialization and is spectrally matched to the source, enabling storage of entangled telecom
photons without spectral modification. We generate and characterize
photon-
memory entanglement from a
quantum interference visibility preserved before and after storage. Harnessing the strong source correlations and the high multimode capacity of the
memory, we access high-dimensional
entanglement spanning 63 temporal modes, reaching a maximum
photon information efficiency of 5.1 Ebits per detected
photon and a peak on-chip
photon-
memory entanglement rate of 5.6 kEbits per second. These results establish a route toward chip-scale
quantum networking hardware operating over telecommunications infrastructure.
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All authors Alexander Kolar, Ian Chin, Conner Fong, Daniil M. Lukin, Melissa A. Guidry, Milan Palei, Jelena Vučković, Tian Zhong
Quantum Physics
Noisy quantum circuit simulation with the tensor jump method
Maximilian Fröhlich, Aaron Sander, Martin Eigel et al. (+2 more)
Classical simulation of noisy
quantum circuits is essential for validating
algorithms, benchmarking hardware, and assessing error-mitigation strategies, but remains limited by the exponential cost of density-
matrix methods and the high variance of standard trajectory sampling. We introduce a variance-aware tensor network framework that combines the tensor jump method with local TDVP gate
evolution on
matrix product states and sparse Pauli-Lindblad hardware noise models. Gates are applied as short variational evolutions on the MPS
manifold, while noise is sampled per
circuit window from Pauli-Lindblad jump sets with state-independent hazards and dissipative contractions that reduce to irrelevant global factors after renormalization. The method supports correlated multi-
qubit Lindblad noise consistent with hardware connectivity, including long-range operators on non-adjacent
qubits, enabling direct simulation of crosstalk and other connectivity-induced errors beyond local noise models. We develop two unbiased variance-aware unravelings. An analog
unitary-mixture unraveling matches the Lindblad generator exactly under symmetric Gaussian or two-point angle laws, while a projector-jump unraveling yields state-independent hazards and closed-form variance laws. Both retain the standard 1/sqrt(N) Monte Carlo convergence but with reduced prefactors. Empirically, projector sampling strongly reduces trajectory variance and bond-dimension growth across many
circuit architectures, whereas analog sampling is most effective at weak noise. We demonstrate accurate, scalable noisy-
circuit simulation on a 25-
qubit noisy XY quench and IBM's 127-
qubit kicked-Ising
benchmark with long-range depolarizing noise, achieving reduced Monte Carlo variance and favorable MPS bond-dimension growth compared with standard Kraus-insertion baselines.
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All authors Maximilian Fröhlich, Aaron Sander, Martin Eigel, Robert Wille, Michael Hintermüller
High Energy Physics (Theory)
Wormholes as red herrings: reflection positivity and the reconstruction of unitary quantum field theories
Jacob McNamara and Zhencheng Wang
As Coleman famously argued, the apparent breakdown of partition-function factorization in
quantum gravity associated with Euclidean wormholes is a red herring, arising from a hidden average over an ensemble of theories. We present a direct analog of Coleman's argument for the apparent breakdown of
Hilbert-space factorization associated with spatial wormholes, i.e., Einstein–Rosen bridges. Our main result is the following reconstruction
theorem for
quantum field theories:
unitary QFTs are determined, up to
unitary isomorphism, by their closed-
manifold partition functions; every reflection-positive partition function arises from a
unitary quantum field theory; and the states prepared by
manifolds span the space of invariant states under the reconstructed theory's
symmetry group. Interpreting the result gravitationally, we conclude that any apparent breakdown of
Hilbert-space factorization is a red herring, arising from restricting to an incomplete spectrum of charged states.
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High Energy Physics (Theory)
The Art of Networking: Networks of Trivalent 10d Heterotic Junctions
Chiara Altavista, Edoardo Anastasi, Roberta Angius et al. (+2 more)
We initiate the study of networks of 10d string theories connected by junctions implied by the cobordism
conjecture. Focusing on the recently constructed junction of the three 10d non-tachyonic heterotic theories, we generalize its $(0, 1)$ heterotic worldsheet description to construct arbitrary networks. For one-dimensional networks, we formulate their
topology in terms of graph theory and provide a simple worldsheet realization for general graphs. We then extend our analysis to higher-dimensional networks, describing e.g. nucleation in a theory of bubbles of pairs of other theories. We also discuss compact configurations, which define a novel class of compactifications in which different sectors propagate on different compact spaces, in a way reminiscent of compactifications on
quantum geometries like $S^1 \vee S^1$.
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All authors Chiara Altavista, Edoardo Anastasi, Roberta Angius, Angel M. Uranga, Chuying Wang
Quantum Physics
Logarithmic negativity typically equals exact entanglement cost
Bowen Ouyang and Jonah Kudler-Flam
Quantum entanglement plays a leading role in modern understanding of physical systems, from
quantum phases of matter to
quantum gravity. In
quantum information theory, one seeks operationally meaningful quantifiers of
entanglement, which for large
quantum systems are notoriously difficult to evaluate due to the lack of computationally efficient
algorithms. In this Letter, we show that for large random induced mixed states the logarithmic negativity, an efficiently computable
entanglement measure, generically coincides with the exact
entanglement cost under positive-partial-transpose-preserving operations, thereby acquiring a precise operational interpretation. Our results establish logarithmic negativity as an exact characterization of
entanglement in generic many-body states and provide a tractable route for quantifying
entanglement in complex
quantum systems.
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High Energy Physics (Theory)
What's the Matter with 3D Gravity?
Robert Bourne, Jackson R. Fliss and Bob Knighton
We revisit the problem of minimally coupling matter to Einstein
gravity in three dimensions with negative cosmological constant. By working in the worldline formalism, we construct a classical phase space on an initial time surface $\Sigma$, which we quantize using
geometric quantization. States in the
Hilbert space correspond to Virasoro conformal blocks with operators of conformal weight $h<c/24$. As an application of our formalism, we compute the partition function on thermal $\text{AdS}_3$ through equivariant localization. Our answer reproduces the AdS$_3$ Wilson spool and agrees with the known one-loop result. It further serves as a
conjecture for the value of the path integral of
gravity minimally coupled to a massive scalar field in thermal $\text{AdS}_3$ to all orders in $G_N$.
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General Relativity and Quantum Cosmology
Impact of Spacecraft Orbit Uncertainties and Velocity Mismodeling on the LISA Gravitational-Wave Response
Lorenzo Speri, Olaf Hartwig, Waldemar Martens et al. (+5 more)
The
Laser Interferometer Space
Antenna (LISA) is a space-based gravitational wave observatory that consists of three spacecraft in a near-equilateral triangular formation. The spacecraft orbits are typically assumed to be perfectly known in LISA data analysis studies, but in reality, the orbit determination process introduces uncertainties in the spacecraft positions and velocities. In this work, we investigate how these uncertainties propagate into the LISA detector output and the impact of neglecting the spacecraft velocities. We quantify these errors in the knowledge of the LISA response using mismatches and discuss the implications for gravitational wave data analysis. We find that spacecraft orbit uncertainties impact the LISA response knowledge at high frequencies with worst mismatch below $10^{-7}$. The effect of neglecting the spacecraft velocities is largest at frequencies around $10^{-4}$ Hz with mismatches of order $10^{-4}$. For a
galactic binary with frequency $10^{-4}$ Hz and SNR=200 observed for one year, we find that neglecting the spacecraft velocities in the response leads to less than 1-$\sigma$ biases in the parameter estimates. This work provides the first characterization of how errors in the LISA gravitational wave response propagate from gravitational wave strain through detector output to estimated parameters.
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All authors Lorenzo Speri, Olaf Hartwig, Waldemar Martens, Oliver Jennrich, Eric Joffre, Michele Armano, Martin Hewitson, Nora Lützgendorf
High Energy Physics (Phenomenology)
No Evidence for Superradiant Axions in LIGO-Virgo-KAGRA GWTC-5 Binary Black Hole Spins
Orion Ning, Benjamin R. Safdi and Catherine Welch
The
quantum chromodynamics (QCD)
axion and
axion-like particles may form bound clouds around spinning black holes (BHs) when their Compton wavelength is comparable to the BH gravitational radius, depleting the BH
spin through what is known as a $\textit{superradiance}$ instability. Using binary BH (BBH)
spin measurements obtained from the LIGO-Virgo-KAGRA GWTC-5 catalog, the most extensive public BBH catalog to date containing $N=257$ mergers with BH masses spanning roughly $5$-$135$ $M_\odot$, we perform a hierarchical
Bayesian analysis in the context of a BH
spin population model to constrain ultralight
axions. The presence of
axions at a given mass would imprint a unique signature in the observed mass-
spin relation relative to the formation distribution. We find no evidence for
axions across more than two decades in mass, excluding
axion masses $1.7 \times 10^{-14} \, {\rm eV} \lesssim m_a \lesssim 3.3 \times 10^{-12} \, {\rm eV}$ at 95% confidence. Because prior superradiance bounds in this range derive from X-ray
spin measurements with substantial modeling systematics, this result represents one of the strongest robust lower bounds on the QCD
axion mass.
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Earth and Planetary Astrophysics
Aerosols and hydrocarbons in the atmosphere of a white dwarf planet
Ryan J. MacDonald, Christopher E. O'Connor, Victoria A. Boehm et al. (+15 more)
Most
stars, including our Sun, will one day evolve into red
giants and, subsequently, white
dwarfs. Several
planet candidates have recently been identified orbiting white
dwarfs, demonstrating that
planets can survive the
stellar post-main-sequence stage intact. Little is known about the atmospheric composition of post-main-sequence
planets, with the most evolved transiting
planets with atmospheric detections to date orbiting subgiants. Here we report an atmospheric detection for the white
dwarf planet WD 1856 b, achieved through transmission spectroscopy with the JWST NIRSpec PRISM. Our 0.5-5.0 $\mu$m spectrum reveals the presence of hydrocarbons (odds ratio of $167:1$ to $5377:1$, with $\mathrm{CH}_4$ preferred at $17:1$ to $30:1$), aerosols ($2 \times 10^5:1$ to $2 \times 10^6:1$), and thermal emission from the planetary nightside ($2 \times 10^{63}:1$ to $2 \times 10^{73}:1$). Our spectral analysis constrains WD 1856 b's mass to $4.3$ to $10.9 \mathrm{M}_J$, finds a carbon-enriched atmosphere (with a $\mathrm{CH}_4$ abundance of $\approx 7\%$), and an effective temperature exceeding the expected planetary
equilibrium temperature ($390$ to $412 \, \mathrm{K}$ vs. $160 \, \mathrm{K}$). Based on cooling models, these results suggest that WD 1856 b underwent a migration-related reheating event $3.0$ to $5.5 \, \mathrm{Gyr}$ into the white
dwarf phase, consistent with post-main-sequence
tidal evolution to the present-day $0.02 \, \mathrm{au}$ circular orbit. Our results provide a window into the ultimate fate of
giant planets orbiting
stars with masses similar to our Sun.
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All authors Ryan J. MacDonald, Christopher E. O'Connor, Victoria A. Boehm, E. M. May, David K. Sing, Elijah Mullens, L. C. Mayorga, Trevor O. Foote, Simon Blouin, Logan A. Pearce, Nikole K. Lewis, Jeff Valenti, Natasha E. Batalha, Maura Lally, Joshua D. Lothringer, Mark S. Marley, Ishan Mishra, Susan E. Mullally
Earth and Planetary Astrophysics
Discovery of an Inflated Hot Neptune and Its Formation from Jovian Mass Loss
Grant C. Weldon, Samuel W. Yee, Bradley M. S. Hansen et al. (+17 more)
The production of Neptune-like
planets with orbital periods of 3–6 days is challenging for conventional models of high-eccentricity migration. We present the discovery and characterization of TOI-2195~A~b, an inflated hot Neptune ($P = 4.16$ days, $m_p= 1.46M_{\rm Nep},\,R_p = 0.79R_{\rm J}$) orbiting an early K-type
star with a wide binary companion at $\sim 600$~au. Detection of the Rossiter-McLaughlin effect at $\sim2.6\sigma$ confidence with Magellan/PFS reveals the
planet is likely on a near-polar orbit with a sky-projected
stellar obliquity $\lambda = {109^{+35}_{-53}} ^{\circ}$. We perform coupled dynamical and structural modeling that reproduces the observed characteristics of the system. We show that the
planet may have originated as a cold, Jovian
planet that was excited to high eccentricities via the
stellar Eccentric Kozai-Lidov (EKL) mechanism, where it lost up to $\sim90\%$ of its mass via Roche lobe overflow during close periastron passages, enabling rapid
tidal migration and radius inflation due to
tidal heating. TOI-2195 A b provides a test for planetary migration theories, and our simulations suggest that puffy hot Neptunes originated as more massive Jovians that underwent mass loss during high-eccentricity migration.
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All authors Grant C. Weldon, Samuel W. Yee, Bradley M. S. Hansen, Smadar Naoz, Joel D. Hartman, Joshua N. Winn, R. Paul Butler, Jeffrey D. Crane, Phil Evans, Tianjun Gan, Steve B. Howell, Michelle Kunimoto, David Osip, David Rapetti, Stephen A. Shectman, Keivan G. Stassun, Johanna K. Teske, Roberto Zambelli, George Zhou, Carl Ziegler
Cosmology and Nongalactic Astrophysics
How I stop worrying about non-universality and $b_\phi$: Constraining local $f_{\rm NL}$ with $b_\phi$ priors from HOD posteriors
Jiaxi Yu and Nhat-Minh Nguyen
Local
primordial non-Gaussianity (local PNG) induces a scale-dependent contribution to
galaxy clustering proportional to $f_{\rm NL}\,b_\phi$, where $f_{\rm NL}$ is the local PNG amplitude and $b_\phi$ encodes the
galaxy response to a long-wavelength
primordial potential perturbation. Uncertainty in $b_\phi$ is the dominant obstacle to precise, robust constraints on $f_{\rm NL}$ from
galaxy surveys. We translate small-scale clustering constraints on the
galaxy–
halo connection into priors on $b_\phi$: sampling the posterior of a
halo occupation distribution (HOD) model fit to the DESI EDR, we generate mocks from which we measure $b_\phi$ and construct its prior. Validating against additional mocks with different local PNG amplitudes, we show that the method recovers unbiased $f_{\rm NL}$, even in the presence of assembly bias.
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Statistical Mechanics
A Fuzzy Sphere Journey in Critical Phenomena
Yin-Chen He and W. Zhu
This review discusses the recently proposed fuzzy sphere regularization for studying $2+1$D critical phenomena, particularly three-dimensional (3D) conformal field theory (CFT). The fuzzy sphere scheme not only offers remarkable efficiency in extracting extensive CFT data at low computational cost but also reveals unexpected connections among 3D CFT (critical phenomena), noncommutative geometry, and the
quantum Hall effect. We introduce the fundamental ideas of fuzzy sphere regularization, emphasizing its role in demonstrating the state-operator correspondence of 3D CFTs on the $S^2 \times \mathbb{R}$ geometry. Additionally, we review key developments in this approach across various directions and outline potential future applications.
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Nuclear Theory
Determining the dynamic deformation of $^{140}$Ce by constraining coupled-channels parameters for fusion
Chandra Kumar, Rohan Biswas, J. Gehlot et al. (+6 more)
We present a systematic study of the dynamic deformation of 140Ce using 16O and 36S projectiles in heavy-ion fusion reactions, combining experimental data, a Gaussian analytic-barrier framework and coupled-channels calculations. Fusion cross sections for 16O+140Ce are measured from ~17% above to ~12.4% below the Bass barrier. Fusion data for 36S+140Ce are obtained from the literature. Deformation parameters of 140Ce are extracted via chi-square minimization and
Bayesian analysis, with independent
Bayesian Model Averaging yielding beta_2 = 0.09 +/- 0.03 and beta_3 = 0.18 +/- 0.02, consistent across both systems. The extracted parameters are tested in the 28Si+140Ce system, where coupled-channels calculations including transfer of a pair of
neutrons (2n) reproduce both the fusion excitation function and the barrier distribution. The positive Q-value 2n-pickup channel enhances fusion in this reaction, while the projectile's vibrational or rotational nature results in similar structure of the barrier distribution. This study demonstrates that the Gaussian analytic recipe is quite effective in deriving the fusion barrier distribution which proves to be a sensitive probe of intrinsic
nuclear deformation. Further, coupled-channels analysis across multiple systems ensures robustness of the extracted deformation parameters.
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All authors Chandra Kumar, Rohan Biswas, J. Gehlot, Gonika, A. Parihari, N. Madhavan, A. Vinayak, Amritraj Mahato, S. Nath
Superconductivity
Ising superconductivity and anomalous metallic states in a bulk crystal with artificial unidirectional stacking layers
Xiangqi Liu, Chen Xu, Haonan Wang et al. (+17 more)
The two-dimensional (2D) limit in macroscopic bulk
crystals provides a powerful platform for exploring exotic
quantum phases. Here, we report the synthesis of a Sr0.75ClNbS2
superconductor that achieves unidirectional, parallel AA stacking-a configuration never before realized in a bulk
crystal. Unlike conventional intercalation, which merely expands the interlayer spacing, our approach employs a planar Sr-Cl network to enforce a complete stacking reorganization, driving all NbS2 layers from the native antiparallel AB stacking into a unidirectional, parallel AA arrangement. This stacking switch globally breaks inversion
symmetry, transforming centrosymmetric 2H-NbS2 into a noncentrosymmetric bulk
crystal with D3h point group
symmetry. Crucially, this structural design reproduces, in three dimensions, the electronic environment of an isolated monolayer, thereby preventing cancellation of the local Ising fields. As a result, strong Ising
spin-orbit coupling and
spin-split bands persist throughout the bulk. Transport measurements reveal extreme superconducting anisotropy ({\gamma} ~ 77), an in-plane upper critical field (~ 10.65 T) that far exceeds the Pauli paramagnetic limit, and clean-limit superconductivity indicative of high crystalline quality. Moreover, magnetotransport uncovers a novel
magnetic-field-induced anomalous metallic state characterized by finite dissipation yet a vanishing
Hall response. Direct band-structure measurements corroborate the layer-decoupled, quasi-2D electronic nature of the system. This work establishes stacking-geometry engineering as a powerful strategy to artificially enforce a globally noncentrosymmetric, quasi-2D superconducting state in bulk
crystals, paving the way for designing
quantum materials with tunable crystalline
symmetry and electronic band
topology.
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All authors Xiangqi Liu, Chen Xu, Haonan Wang, Runfeng Zhang, Ziyi Zhu, Zhengyang Li, Lianbing Wen, Ze Yan, Fanbo Shen, Jiawei Luo, Zhengtai Liu, Xia Wang, Leiming Chen, Ke Qu, Jianping Sun, Jinguang Cheng, Shiwei Wu, Zhenzhong Yang, Dawei Shen, Yanfeng Guo