Quantum Physics
The Optimal Rate Function in Covariant Quantum State Tomography
Arick Grootveld, Alexander Maloney, Jason Pollack et al. (+1 more)
The problem of
quantum tomography is to estimate an unknown
quantum state $\rho$ from a measurement of $n$ copies of $\rho$. One can ask which
tomography protocol, i.e.\ which choice of multi-copy measurement, gives the best possible estimate of $\rho$. To do so, we characterize
tomography protocols by their rate function, which governs the exponential rate at which a protocol assigns probability to a particular estimate $\sigma$ of the true state $\rho$. This rate function is a
quantum mechanical generalization of the classical relative
entropy between the true state and its estimate, and depends on the choice of protocol. It is bounded by the
quantum relative
entropy, and we show that this bound is sharp: for any $\rho$ and $\sigma$ we construct a family of protocols whose rate functions converge to the
quantum relative
entropy $D(\sigma\|\rho)$. We consider the family of covariant
tomography protocols; these are the basis independent state estimation schemes that assume no prior information about $\rho$ and $\sigma$. Keyl described a specific
tomography protocol based on Schur sampling, and conjectured that among all covariant
tomography protocols it has the largest possible rate function for all $\sigma$ and $\rho$. We prove this
conjecture. The resulting rate function is an annealed version of
quantum relative
entropy, due to the cost of learning the eigenbasis in covariant
quantum state
tomography.
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All authors Arick Grootveld, Alexander Maloney, Jason Pollack, Peixue Wu
Mathematical Physics
Self-Adjointness of the Standard Model of Non-Relativistic QED
Valentin Kußmaul
For systems of non-relativistic charged particles minimally coupled to the soft modes of the quantized radiation field, we prove self-adjointness on the domain of the free
Hamiltonian. This result is not new, but the proof we give shortens previous arguments. It is based on a comparison of graph norms and Nelson's commutator
theorem.
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Quantum Physics
Counterdiabatic Raman Atom Optics for Compact High-Sensitivity Gravimetry
Asad Ali, Hamid Arian Zad, Saif Al-Kuwari et al. (+6 more)
Large-momentum-transfer (LMT) atom interferometry provides a route toward enhanced inertial sensitivity in compact
quantum sensors, but its scalability is limited by the accumulation of pulse-transfer errors across long Raman pulse sequences. We investigate theoretically the use of stimulated Raman shortcut-to-adiabatic passage (STIRSAP) for high-fidelity LMT atom optics in a Mach–Zehnder interferometer geometry. The counterdiabatic correction is encoded directly into the Raman pulse envelopes, eliminating the need for auxiliary microwave or
radio-frequency control fields. Numerical simulations based on an effective Raman model show that $1~\mu\mathrm{s}$ STIRSAP pulses achieve single-pulse transfer fidelities of $F_\pi = 0.99902$ while maintaining negligible pulse-time overhead even at high momentum order. We analyze the resulting tradeoff between interferometric phase enhancement and compound contrast decay and identify an unconstrained shot-noise optimum near $n\approx270$. The analysis further shows that practical operation at extreme LMT order is constrained by wave-packet separation, vibration noise, Doppler detuning, and accumulated systematic effects rather than by pulse duration itself. These results establish superadiabatic Raman control as a promising approach for scalable high-fidelity atom optics and clarify the physical limitations governing compact high-order atom interferometers.
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All authors Asad Ali, Hamid Arian Zad, Saif Al-Kuwari, Muhammad Irtiza Hussain, Muhammad Talha Rahim, Hashir Kuniyil, Tim Byrnes, James Q. Quach, Saeed Haddadi
Quantum Gases
Adiabatic realization of anomalous Floquet topological systems
Luca Asteria, Marcel N. Kosch, Henrik P. Zahn et al. (+4 more)
Topology has emerged as a central concept for classifying phases of matter. The situation is especially rich in periodically driven systems, where anomalous Floquet topological phases break the usual bulk-boundary correspondence between Chern number and edges modes of two-dimensional systems. These phases were so far realized by periodic modulation of the tunneling elements at frequencies near-resonant with respect to the system's bandwidth, a regime where Floquet heating plays a significant role in interacting systems. Here we show that such anomalous Floquet topological phases can also be realized by means of an adiabatic protocol, where the system is always in the instantaneous ground state of the cyclic path in parameter space, like in a Thouless charge pump. We experimentally realize such a state using ultracold atoms in a hexagonal
lattice where we adiabatically modulate the
lattice geometry, including the sublattice offset. To infer the
topology, we use the micromotion area in real-space, which was recently identified as a proxy for the winding number. This way of realizing anomalous phases avoids resonant Floquet heating and imperfect loading into the target state. We demonstrate the robustness of the adiabatic construction by observing the anomalous phase even in the presence of mean-field interactions of magnitude comparable to all other energy scales. These findings are promising for engineering novel topological states in a more robust way.
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All authors Luca Asteria, Marcel N. Kosch, Henrik P. Zahn, Jonathan Bracker, André Eckardt, Klaus Sengstock, Christof Weitenberg
Optics
Edge-enhanced diffractive neural networks based on spin-multiplexed nonlocal metasurfaces
Qianqian He, Kenan Guo, Jumin Qiu et al. (+3 more)
Single-layer diffractive neural networks often face classification accuracy bottlenecks due to limited wavefront modulation capabilities. Edge detection, as an optical image processing technique, extracts image contours and offers a promising way to simplify classification tasks. However, integrating edge detection and DNN-based classification on a single chip remains a challenge. Here, we propose an integrated nonlocal meta-platform that sequentially achieves all-optical edge detection and classification via
spin-multiplexing. By exploiting the dispersion properties of the nonlocal Huygens' metasurface, the co-polarized component in the output light performs momentum-space filtering for real-time edge detection. Subsequently, the cross-polarized component undergoes
geometric phase modulation to execute image classification within the DNN. We couple quasi-bound states in the continuum and
magnetic dipole resonances in crescent-shaped nanopillars, achieving a high polarization conversion efficiency of approximately $55\%$. This edge-enhanced DNN architecture significantly reduces data redundancy, elevating the classification accuracy of the single-layer network on the MNIST
dataset from $64.2\%$ to $80.7\%$. Our work provides a compact, high-efficiency solution for integrated all-optical machine
vision and intelligent photonic computing.
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All authors Qianqian He, Kenan Guo, Jumin Qiu, Huifu Qiu, Shuyuan Xiao, Tingting Liu
Other Condensed Matter
Time-of-flight photon spectroscopy for scanning tunneling microscopy luminescence
Lebin Yu, Jiří Doležal, Maximilian Rödel et al. (+4 more)
We build and commission a time-of-flight
photon spectrometer (TOFS) for scanning tunneling microscopy luminescence (STML). We obtain the spectrum by exploiting the wavelength dependent refractive index of a long dispersive optical fiber that converts
photon arrival times into wavelength information; blue
photons are delayed more than red
photons. The setup uses a pulsed excitation source, either
laser flashes or voltage pulses, to launch the
photons from the junction into a single
photon detector. The TOFS calibration can be performed and transferred to the STML setup from a separate benchtop experiment using pulsed light sources with known wavelength. We verify the TOFS during STML operation by simultaneously recording luminescence from the Ag-Ag(111) plasmon using a conventional grating spectrometer. Our experiments show that the TOFS is a straightforward and cost-effective addition to existing STML setups with good performance in the near-infrared range. The TOFS is compatible with a drop-in replacement of the single
photon detector such as a superconducting nanowire single
photon detector or even bolometers that may expand the useful spectral range beyond the abilities of current STML setups.
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All authors Lebin Yu, Jiří Doležal, Maximilian Rödel, Amandeep Sagwal, Benjamin Frölich, Martin Švec, Fabian Donat Natterer
Quantum Physics
Experimental quantum state learning with pairs of photons
C. Pria Dobney, Johan Henaff, Allen Kasum et al. (+5 more)
Tomography allows one to estimate the density
matrix describing the state an ensemble of
quantum systems are prepared in (for example, polarization
tomography determines the polarization state of a beam of identically prepared
photons). In general, it is not possible to uniquely decompose the density
matrix into its pure state components. Agarwal et al. proposed a protocol which, for a mixture composed of any two pure states of a
qubit (with arbitrary probabilities), allows an observer to infer not only the density
matrix but the identity of those specific pure states and their weights - the additional requirement being that the
qubits arrive in pairs, where both
qubits in each pair are in the same state. We experimentally demonstrate this learning-from-pairs concept using
photons in the polarization degree of freedom. We use
tomography to measure a sequence of single
photons and make use of their time-of-arrival information to 'pair up' the
photons after the measurement. From here we are able to infer the
photons' polarization states and their respective probabilities, and we demonstrate this for various different choices of polarization states and ratios. Finally, we investigate our ability to discriminate between two equal mixtures of distinct pairs of orthogonal polarization states. We find that on the order of approx. 10e4
photons is typically enough to achieve
tomography fidelities of approximately 0.9999. This is sufficient to discriminate between two different preparations of the same mixed state, differing by angles of less than 5 degrees between the pure states used in the two preparations.
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All authors C. Pria Dobney, Johan Henaff, Allen Kasum, Rui Jie Tang, Haru Mukumoto, Mark Hillery, Berthold-Georg Englert, Aephraim Steinberg
Superconductivity
Steering and Local Tunneling Signatures of Majorana Corner Modes in Altermagnetic Josephson Junctions
Yu-Xuan Li and Tao Zhou
Dynamical manipulation of Majorana zero modes and their reliable distinction from topologically trivial states remain paramount challenges in topological
quantum computation. Here, we propose a phase-biased altermagnetic Josephson junction as a versatile platform for generating and controlling Majorana corner configurations. Our platform utilizes the macroscopic superconducting phase difference and the Néel-vector orientation as independent control knobs to reshape the boundary mass. This allows the spatial configuration of Majorana corner modes (MCMs) to be selected at different corners of a fixed device geometry. This spatial reconfiguration yields a control-correlated conductance response. Across these configurations, the quantized zero-bias peak appears at the contacted corner in the ideal tunneling model when an MCM is present and is suppressed when it is absent. This correlation connects phase and
magnetic control of corner configurations with local tunneling readout.
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Optics
A Scalable All-to-All Reconfigurable Ising Solver Using Pulsed Time-Division Multiplexing
Henry Love, Zhehao Yu, Mohammad Alimadadi et al. (+6 more)
Physics-based computing platforms, such as those based on the Ising model, are an important pillar of future hardware systems built for the artificial intelligence (AI) era. Such platforms show promise for solving nondeterministic
polynomial (NP) time problems that are difficult for traditional processing units to solve efficiently as problem size grows. Here, we present a scalable optoelectronic Ising machine architecture, demonstrated with 64 all-to-all connected
spins using pulsed time-division multiplexing. The 65 nm CMOS Ising chip integrates the coupling and nonlinear mechanisms in an active area of 3.1 mm2, eliminating the need for benchtop equipment within the loop. The feedback loop of the Ising machine is closed using a compact high-bandwidth, low-loss optical fiber, seamlessly combining optical scalability with the ultradense reconfigurability of integrated electronics. The chip operates at 1 GHz with 4-bit coupling weights and is benchmarked with NP-complete Boolean satisfiability problems consisting of three literals (3-SAT) and clause-to-variable ratios of 32/32, 40/24, and 48/16. Nanosecond annealing times represent at least a three order-of-magnitude improvement over previously reported all-to-all connected works. Time and energy to solutions for 100% 3-SAT clause accuracy are as low as 7.4 us and 2.9 uJ, respectively, achieving more than an order-of-magnitude decrease in time and energy to solution compared to the state of the art. All-to-all connection is demonstrated using MaxCut problems with 100% graph densities. The chip's ability to effectively solve 2-, 3-SAT, and MaxCut problems highlights its reconfigurability and versatility. Furthermore, combining mature CMOS integration with scalable photonic links allows for significant reduction in computation time and energy, addressing the pressing requirements of AI and future hyperscale datacenters.
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All authors Henry Love, Zhehao Yu, Mohammad Alimadadi, Yan Jin, Nitesh Chauhan, Brian Edwards, Pratik Chaudhari, Scott B. Papp, Firooz Aflatouni
Astrophysics of Galaxies
Detection of C$_{60}$ Combination Bands in the Near-IR Spectrum of Tc 1
Morgan M. Giese, Vincent J. Esposito, Simon Van Schuylenbergh et al. (+26 more)
We report the detection of a set of new near-infrared emission features between 3.5 and 5.2 ${\mu}$m in JWST/NIRSpec observations of Tc 1, the planetary nebula known for displaying the cleanest and most prominent mid-infrared
cosmic fullerene spectrum. These broad features share the same spatial distribution as the well-known C$_{60}$ and C$_{70}$ mid-infrared emission bands, peaking in an asymmetric ring approximately 5-6" from the central
star. Through comparison with new anharmonic
quantum chemical calculations, we demonstrate that these features arise from C$_{60}$ combination bands, marking their first detection in an astrophysical environment. The total energy radiated in the combination bands amounts to ~17% of the total energy emitted from all C$_{60}$ modes, with direct implications for fullerene cooling models. These near-infrared combination bands offer a promising new window for identifying and studying the molecular astrophysics of C$_{60}$ in sources where mid-infrared spectra are more complex.
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All authors Morgan M. Giese, Vincent J. Esposito, Simon Van Schuylenbergh, Jan Cami, Els Peeters, Charmi Bhatt, Dries Van De Putte, A. G. G. M. Tielens, Michael J. Barlow, Jeronimo Bernard-Salas, Alessandra Candian, Bryan Changala, Nick L. J. Cox, Harriet L. Dinerstein, D. A. García-Hernández, Marco A. Gómez-Muñoz, Kay Justtanont, Kathleen E. Kraemer, Eric Lagadec, Arturo Manchado, Ana Monreal Ibero, Raghvendra Sahai, Ameek Sidhu, G. C. Sloan, N. C. Sterling, Jeremy R. Walsh, Roger Wesson, Joshua Cole Whitman, Albert Zijlstra
Instrumentation and Methods for Astrophysics
Graph Neural Networks Trained on Null Signal for Angle Reconstruction in X-ray Polarimetry
Vittorio Latorre, Victor Rodriguez-Fernandez, Alessandro Di Marco et al. (+3 more)
Scientific real detectors often produce sparse, irregular data defined on non-Euclidean domains, where conventional convolutional neural networks (CNNs) impose
geometric biases that distort physical observables. In X-ray polarimetry, such distortions can mimic polarization signals at the percent level, critically limiting measurement fidelity. We consider a framework based on Graph Neural Networks (GNNs) for reconstructing photoelectron emission angles from Gas Pixel Detectors, operating directly on their native sparse hexagonal
topology. The network is trained solely on unpolarized simulated data and integrates rotational data augmentation, ensemble averaging, and modulation-aware model selection to reduce spurious angular modulation. Despite never encountering polarized examples, the model is able to recover the overall structure of polarized signals. Compared with the classical Method of Moments (MoM), an analytical approach to track angle reconstruction, the proposed GNN achieves lower per-track error but yields worse performance for polarimetry, revealing a mismatch between local reconstruction accuracy and global polarimetric performance. Compared to CNN-based approaches, the framework shows competitive performance on both unpolarized and polarized reconstructions, despite being trained in a more challenging power-law energy distribution. These results position the method as a diagnostic tool to highlight the limitations and trade-offs of learning-based approaches for X-ray-polarimetry signal reconstruction.
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All authors Vittorio Latorre, Victor Rodriguez-Fernandez, Alessandro Di Marco, Fabio La Monaca, Fabio Muleri, Paolo Soffitta
Quantum Physics
Controlled Quantum Metrology with Anisotropic Heisenberg Spin Interactions under Intrinsic Decoherence
S.K. Singh, Jia-Xin Peng, Y-J Zhu et al. (+1 more)
We theoretically investigate
quantum parameter estimation in a two-
qubit anisotropic Heisenberg
spin system with Dzyaloshinskii-Moriya (DM) interaction in the presence of intrinsic decoherence described by the Milburn model. Using the
Quantum Fisher Information (QFI), we study the estimation of both the uniform
magnetic field and the DM interaction strength. Analytical expressions for the time-evolved density
matrix are obtained and used to explore the effects of exchange anisotropy, intrinsic decoherence, and probe-state preparation on the achievable estimation precision. Our results show that suitable tuning of the anisotropic exchange coupling and the initial entangled state can considerably enhance the estimation performance, with different optimal parameter regimes emerging for
magnetic-field and DM-interaction sensing. To better understand the role of
quantum resources in metrology, we also examine the behaviour of concurrence,
quantum coherence, and von Neumann
entropy. Overall, our findings demonstrate that anisotropic Heisenberg
spin systems with DM interaction provide a promising and flexible platform for high-precision
quantum metrology even in the presence of intrinsic decoherence.
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All authors S.K. Singh, Jia-Xin Peng, Y-J Zhu, Mohammad Khalid
Quantum Physics
Analytic Benchmarks for Coherence-to-Entanglement Conversion under Post-Gate Noise in CNOT-Based Protocols
Asad Ali, H. Kuniyil, M.I. Hussain et al. (+3 more)
Coherence-to-
entanglement conversion transforms single-
qubit superposition into a practical two-
qubit resource, but noise limits this process in near-term
quantum hardware. We derive closed-form
benchmarks for a minimal CNOT primitive in which a coherent
qubit and an incoherent ancilla generate
entanglement before undergoing phase damping, global depolarizing, amplitude damping, or independent local depolarizing noise. Using the $\ell_1$-norm of coherence and negativity, we prove the noiseless law $\mathcal{N}_0=C_{\ell_1}/2$, valid for arbitrary mixed inputs, and obtain exact negativities, survival fractions, and
entanglement-sudden-death thresholds. For all $X$-state-preserving channels, a master relation shows that
entanglement loss results from the competition between coherence suppression and partial-transpose spectral shifts. Phase damping yields $\eta=1-p$ without finite-noise sudden death; global depolarization gives coherence-dependent sudden death; amplitude damping adds an excited-population penalty and sudden death only for $\theta>\pi/4$; while local depolarization is most destructive at equal depolarizing strength. The initial survival slopes, $-1$, $-3/2$, $-2$, and $-3$, act as compact noise fingerprints. Since concurrence satisfies $C=2\mathcal{N}$ for the generated states, all robustness rankings remain unchanged. Mapping channel parameters to $T_1$, $T_\varphi$, and average gate fidelity connects the theory to hardware-level performance.
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All authors Asad Ali, H. Kuniyil, M.I. Hussain, M.T. Rahim, Abdallah Slaoui, Saif Al-Kuwari
Astrophysics of Galaxies
Magnetic Fields in Massive Star-forming Regions (MagMaR). VII. On the dynamical importance of B-fields in massive protocluster W33 A
Fengwei Xu, Q. Zhang, P. Sanhueza et al. (+30 more)
Magnetic fields (B-fields) are likely important in massive protocluster formation, but their role remains poorly constrained. We present 1.2 mm ALMA full-polarization observations of W33 A, a massive
star-forming region at 2.4 kpc, with an angular resolution of 0.3 arcsec (730 au). The region is resolved into 20 dense cores and 9 filaments. The plane-of-sky B-field, inferred from linearly polarized
dust emission, shows diverse structures: two nearly perpendicular large-scale components oriented northwest-southeast (NW-SE) and northeast-southwest (NE-SW), and two localized features toward the millimeter peaks MM1 and MM2. The NW-SE component could be shaped by a molecular
outflow. The NE-SW component is coherent along the main filaments F1, F-Main, and Tail, all of which show trans-Alfvenic
turbulence. In F-Main, the line mass exceeds the turbulent critical value, implying that
magnetic support is required to prevent radial collapse and suppress fragmentation. In F1 and Tail,
turbulence alone can support the gas against
gravity, although B-fields may provide additional support. Toward MM1, the B-field follows a spiral-like infalling streamer traced by CH3CN. The trans-Alfvenic state of the accreting gas suggests efficient
magnetic damping of
turbulence and a magnetically regulated, laminar
accretion flow feeding the core. Toward MM2, the B-field shows an hourglass morphology fitted by
parabolic curves. Two independent methods give a consistent field strength of about 8.1(1.9) mG, and virial analysis indicates that the B-field is dynamically important in delaying collapse of MM2. Within a single protocluster, B-fields can stabilize filaments, regulate
accretion, and delay core collapse, highlighting their diverse dynamic role in high-mass
star formation.
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All authors Fengwei Xu, Q. Zhang, P. Sanhueza, K. Wang, Hauyu Baobab Liu, H. Beuther, Wenyu Jiao, C. Wang, P. C. Cortés, P. M. Koch, J. M. Girart, M. T. Beltrán, J.-W. Wang, J. Liu, F. A. Olguin, Xing Lu, S. Li, Pak Shing Li, T. Liu, K. Morii, J. Hwang, H.-R. V. Chen, S. Jiao, Y. Cheng, Q. Luo, Piyali Saha, Ji-hyun Kang, C. Y. Law, L. K. Dewangan, O. R. Jadhav, E. J. Chung, Chakali Eswaraiah, Luis A. Zapata
Quantum Gases
Band-minimum degeneracy is not enough: density-of-states control of low-density ferromagnetism
Jinghao Wang and Pierbiagio Pieri
Recent ultracold-atom experiments have observed
ferromagnetic correlations in a geometrically tunable
Fermi–Hubbard
lattice at intermediate densities. Motivated by subsequent theoretical work that connected the low-density limit of the same model to the Mueller–Hartmann mechanism for itinerant ferromagnetism, we investigate the stability of ferromagnetism across a broad density range using the T-
matrix approximation, a controlled approach in the dilute limit. We reproduce the
ferromagnetic regime observed experimentally at intermediate densities and systematically compare finite-size and thermodynamic-limit calculations in the dilute regime. We find that the low-density
ferromagnetic phase reported for the one-diagonal hopping
lattice is strongly suppressed with increasing system size and disappears in the thermodynamic limit, indicating that it originates from finite-size effects. By contrast, low-density ferromagnetism remains robust in the square-
lattice Hubbard model with hopping along both diagonal directions. We show that this qualitative difference cannot be explained by the degeneracy of the band minima alone, which occurs in both models. Instead, it is controlled by the singular behavior of the density of states at the band bottom: a weak divergence is insufficient to stabilize ferromagnetism, whereas a much stronger quasi-one-dimensional singularity supports a fully polarized ground state even in the dilute limit. Our results demonstrate that band-minimum degeneracy alone is not sufficient for low-density ferromagnetism and that the nature of the band-bottom density-of-states singularity ultimately controls its stability.
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High Energy Physics (Theory)
Quantum gravity and spectral running cutoff
Carlo Branchina, Vincenzo Branchina, Filippo Contino et al. (+2 more)
We have recently shown that a natural way to implement the Wilsonian paradigm in gauge theories is through the introduction of a “spectral cutoff", a cut on the
eigenvalues of the covariant
Laplacian, pointing out that this provides the route toward the renormalization group (RG) construction. Here we apply this idea to
quantum gravity, resorting to two realizations of the spectral running cutoff: “hard" and “smooth". We derive the RG equations for the Newton and cosmological constant and find the RG pattern of the asymptotic safety scenario, with a non-Gaussian UV-attractive fixed point.
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All authors Carlo Branchina, Vincenzo Branchina, Filippo Contino, Riccardo Gandolfo, Arcangelo Pernace
General Relativity and Quantum Cosmology
Fixed-quadrupole static tidal response of Schwarzschild black holes in a cubic Weyl effective field theory
Edilberto O. Silva
Static Love numbers of four-dimensional Schwarzschild black holes vanish in general relativity. We study how the fixed-quadrupole static
tidal solution is modified by the parity-even cubic Weyl operator in the gravitational effective field theory. Working perturbatively in $\epsilon_{\rm e}=\lambda_{\rm e}(\Lambda r_s)^{-4}$, we construct the reduced quadratic radial action for static even-parity $\ell=2$ perturbations, order-reduce the higher-derivative equations, and solve the resulting boundary-value problem directly in metric variables. The order-$\epsilon_{\rm e}$ equations reduce to a first-order two-dimensional inhomogeneous system for $X_0$ and $X_K$, with $X_2$ fixed by an algebraic constraint. Horizon regularity leaves one constant, but matching to infinity shows that this freedom only renormalizes the applied
tidal branch. After removing this
tidal renormalization, the decaying branch is unambiguous. Calibrating the spatial sector at fixed $\ell=2$ against the associated-Legendre branches $P_2^{2}$ and $Q_2^{2}$, we obtain a fixed-quadrupole response amplitude $\Delta(B/A)=-2400\epsilon_{\rm e}$. Equivalently, the scalar fixed-$\ell$ quotient gives $\Delta k_{2,\rm sc}^{\rm fix}=-20\epsilon_{\rm e}$. The second number is a scalar fixed-$\ell$ conversion of the metric branch ratio, not, by itself, the analytically continued, gauge-invariant electric Love number. A comparison with canonical Teukolsky-based Love numbers requires an additional continuation in $\ell$ and a precise map of normalizations. The result should therefore be viewed as a reproducible metric-sector
benchmark for the cubic Weyl EFT, complementary to gauge-invariant master-equation approaches.
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Cosmology and Nongalactic Astrophysics
Analytic results for slow-roll curved-space inflation and exponential potentials
Dimitrios Tsimpis and Govind Venugopal
We derive analytic templates for the scalar and tensor
primordial power spectra describing cosmologies that transition from kinetic dominance to slow-roll inflation in the presence of spatial
curvature. Our results extend recent works in the literature, allowing us, in particular, to recover the scalar and tensor tilts analytically. We revisit the case of
curvature-assisted single-exponential models in light of this framework. In the case of an open universe, the phase space of such models naturally includes cosmologies that start out in a kinetic-dominance regime followed by a parametrically controlled quasi-de Sitter phase. However, they do not fit in the framework of the templates, as their second Hubble slow-roll parameter remains of order one in the quasi-de Sitter regime.
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Optics
Coupled Flexural Optomechanical Cavities with Engineered Nanomechanical Interconnects
David Alonso-Tomás, Guillermo Arregui, Bingrui Lu et al. (+3 more)
Integrated nanomechanical
circuits require compact and predictable ways to read out, confine, and connect mechanical motion across multiple nanoscale elements. This challenge is particularly acute for megahertz flexural modes, whose large mechanical response and nonlinear dynamics are attractive for optomechanics, sensing, and signal processing, but whose extended nature makes local confinement and coupling difficult within dense devices. Here we demonstrate an optomechanical nanobeam platform in which optical transduction and mechanical connectivity are both engineered lithographically. Transverse
geometric asymmetry in the photonic-
crystal cavity breaks the cancellation that suppresses dispersive coupling to in-plane flexural motion, making these modes optically bright without ancillary structures. In parallel, serpentine mechanical links engineered through their complex band structure act as compact mirrors and evanescent couplers for MHz flexural waves. In coupled-cavity devices, the normal-mode splitting decays exponentially with the number of serpentine
cells, yielding an experimental attenuation constant in quantitative agreement with full-system simulations. Geometry-dependent measurements further show that the coupling can be tuned by the interconnect design and identify regimes where finite-link modes hybridize with the cavity modes, beyond a simple two-resonator picture. These results establish complex-band-engineered mechanical links as calibrated interconnects for scalable optomechanical nanocircuits based on optically addressable MHz flexural resonators.
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All authors David Alonso-Tomás, Guillermo Arregui, Bingrui Lu, Sergei Lepeshov, Søren Stobbe, Daniel Navarro-Urrios
Physics and Society
The Winner Takes It All
P. L. Krapivsky
The winner-takes-all process takes place on an arbitrary graph. There is an
agent on each vertex of the graph, and active
agents at neighboring vertices play games. In each game, a randomly chosen
agent wins, while the loser is eliminated from subsequent games. The games are played at random times, finishing instantaneously, and ceasing when each active
agent has only losers among its neighbors. On the one-dimensional
lattice, the fraction of winners in the final state is $e^{-1}$; we also determine the fractions $w_j$ of winners who won $j=0, 1, 2$ games. For finite segments, we determine statistics of the total number of winners (the average, the variance, and all higher cumulants), the probabilities of attaining the minimum or maximum possible number of winners, and establish the behavior near the boundaries. For infinite regular trees with vertices of degree $d$, i.e., Bethe
lattices with coordination number $d$, we show that the fraction of winners is $(2/d)^{d/(d-2)}$.
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Mesoscale and Nanoscale Physics
Distinguishing between Direct and Parametric Driving in Nanomechanics Using a Vibrating Carbon Nanotube
Sam Dicker, Patrick Steger, Deepanjan Das et al. (+2 more)
Parametric driving is a powerful route to amplification and nonlinear control in nanomechanical resonators, but its signatures can be ambiguous because standard dc electrical readout does not directly reveal the frequency of motion. Here we resolve this ambiguity by measuring the motional frequency of a vibrating carbon nanotube independently of the drive frequency. We operate the nanotube as an electromechanical mixer and detect microwave sidebands using a low-noise superconducting amplifier. This frequency-resolved readout distinguishes direct motion of the first overtone from parametric motion of the fundamental, even when the corresponding drive frequencies nearly coincide. The two mechanisms are further separated by their drive-power dependence. Beyond conventional parametric resonance at $2f_0$, we observe responses to driving at $3f_0$ and $4f_0$, consistent with high-order parametric excitation associated with nonlinear stiffness terms.
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All authors Sam Dicker, Patrick Steger, Deepanjan Das, Saba M. Khan, Edward A. Laird
General Relativity and Quantum Cosmology
Non-linear stability of the matter dominated universe
David Fajman and Elliot Marshall
We numerically study non-linear perturbations of the Einstein-de Sitter spacetime as a solution to the Gowdy-symmetric Einstein-Euler system for a polytropic equation of state. The results suggest that the Einstein-de Sitter spacetime is stable for sufficiently small but otherwise generic perturbations. This is in stark contrast to the well known instability of this spacetime when the matter model is
dust. Moreover, this indicates a previously unknown stable regime of the Einstein-Euler equations with direct implications for cosmology.
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Lattice Field Theory
Direct calculation of parton distributions in momentum space from lattice QCD
Anthony V. Grebe, Daniel C. Hackett, Michael L. Wagman et al. (+2 more)
Coulomb-gauge quasi-parton distributions can be computed directly in momentum space on a finite
lattice, enabled by the commutativity of their renormalization and
Fourier transform. This approach removes the formal inverse problem in coordinate-space methods. Our momentum-space pion quasi-distributions agree with coordinate-space results
Fourier transformed with asymptotic extrapolation, indicating that the formal inverse problem in the latter is not a concern at this volume. We further extend the framework to higher dimensions and obtain the first 3D image of the pion directly from
lattice QCD.
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All authors Anthony V. Grebe, Daniel C. Hackett, Michael L. Wagman, Rui Zhang, Yong Zhao
Strongly Correlated Electrons
Spin-orbit-entangled $J_{\rm eff}=\frac{1}{2}$ magnetism and unconventional spin freezing in the bond-disordered pyrochlore antiferromagnet NaCdCo$_2$F$_7$
Andrej Kancko, Hironori Sakai, Javier Herrero-Martín et al. (+6 more)
Bond disorder in frustrated pyrochlore antiferromagnets can give rise to fundamentally different
quantum ground states depending on the nature of the local
magnetic moments. Here, we show that the bond-disordered $J_{\rm eff}=\frac{1}{2}$ pyrochlore antiferromagnet NaCdCo$_2$F$_7$ realizes an unconventional
spin-glass-like state with continued dynamics, in stark contrast to its isostructural $S=\frac{1}{2}$ NaCdCu$_2$F$_7$ counterpart. High-field magnetization and Co $L_{2,3}$-edge XAS/XMCD establish
spin-orbit-entangled $J_{\rm eff}=\frac{1}{2}$ Co$^{2+}$ moments with a substantial unquenched orbital contribution, consistent with local $XY$ anisotropy seen in the isostructural Na$A''$Co$_2$F$_7$ ($A''$ = Ca, Sr) analogues. $\mu$SR and $^{23}$Na NMR measurements reveal progressive slowing of
spin fluctuations below $\sim10$ K, culminating in a partially frozen state with persistent low-temperature dynamics that deviates from a canonical
spin glass. Comparison with the isostructural bond-disordered pyrochlore NaCdCu$_2$F$_7$, which realizes a random-singlet state, reveals a fundamentally different response of
spin-orbit-entangled Co$^{2+}$ moments to bond disorder. These results identify
spin-orbit coupling as a key ingredient governing the fate of bond-disordered frustrated pyrochlore magnets.
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All authors Andrej Kancko, Hironori Sakai, Javier Herrero-Martín, Adam Berlie, Marc Uhlarz, Tetiana Haidamak, Milan Klicpera, Yo Tokunaga, Ross H. Colman
Quantum Physics
Morphology-resolved scrambling in a chaotic quantum billiard
Pranaya Pratik Das
Chaotic
quantum systems can retain spatial
memory through scarred eigenstates, but whether these static structures control scrambling remains unclear. This work establishes a morphology-resolved connection between scarred eigenstates and eigenstate-resolved OTOCs in a peanut-shaped
quantum billiard. Scalar localisation diagnostics, including differential
entropy and continuum participation ratios, detect anomalous concentration but discard spatial architecture. A scale-normalised density overlap, in contrast, directly compares probability density profiles, revealing families of orthogonal eigenstates with nearly identical spatial morphology. Comparing the complete OTOC time traces of these orthogonal eigenstates reveals that morphological recurrence has dynamical content: moderate density overlap yields no universal prediction, whereas strongly recurring morphologies exhibit nearly identical OTOC growth and saturation. Thus, scarred structures act as spatial templates for operator growth, not merely static violations of ergodicity. This morphology-resolved framework turns eigenstate shape into a quantitative predictor of scrambling and provides a scale-controlled diagnostic of weak ergodicity breaking in
quantum chaos.
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High Energy Physics (Experiment)
Studies of Neutrino-Nucleus Elastic Scattering with Point-Contact Germanium Detectors at the Kuo-Sheng Reactor Neutrino Laboratory
TEXONO Collaboration: M.K. Singh, S. Karmakar, Greeshma C. et al. (+35 more)
The low energy and intense flux of electron anti-
neutrinos from
nuclear reactors provide the perfect stage to study elastic
neutrino-
nucleus scattering ($\nu A_{el}$) in the fully coherent regime. We report results from the TEXONO experiment using electro-cooled $p$-type point-contact Germanium detectors with masses of 523~g and 1434~g at the Kuo-Sheng Reactor
Neutrino Laboratory. We report improved constraints on the $\nu A_{el}$ cross section with a combined exposure of 404(813.7)~kg-days of Reactor ON(OFF) data at an electron-equivalent threshold of 200~eV$_{ee}$. The Lindhard model, in which the quenching factor is parameterized by a single parameter k, is adopted to describe the suppression of ionization yield. At the
benchmark value of k=0.162, a limit of $\rho<$2.0 at 90% confidence level (CL) is derived, where $\rho$ represents the ratio of the observed to the predicted Standard Model cross section. Moreover the region k$>$0.205 is excluded at 90% CL using the SM-predicted $\nu A_{el}$ rate. A bound on the
neutrino magnetic moment from $\nu A_{el}$ at $\mu_{\nu} {<} 5.9 \times 10^{-10}~\mu_B$ at 90% CL is also derived.
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All authors TEXONO Collaboration: M.K. Singh, S. Karmakar, Greeshma C., H.B. Li, F.K. Lin, V. Sharma, L. Singh, H.T. Wong, L.T. Yang, M. Agartioglu, J.H. Chen, J.W. Chen, C.I. Chiang, M. Deniz, T. Guo, H.C. Hsu, W.H. Kao, S. Karadaǧ, J.B. Legras, C.H. Leung, J. Li, T.Y. Liang, S.T. Lin, S.K. Liu, H. Ma, V. Marian, D. Mishra, M.K. Pandey, K. Rani, K. Saraswat, M.K. Singh, V. Singh, D. Tanabe, J.S. Wang, Y.F. Wang, C.-P. Wu, C.H. Yeh, Q. Yue
Mathematical Physics · Cross-listed from math.GR
The Weyl-orbit embedding and a representation-theoretic characterization of the Clifford hierarchy
Asgar Jamneshan and Berke Ünal
Bu, Gu, and Jaffe introduced the
quantum uniformity measures to analytically characterize the Clifford hierarchy. We prove that the
quantum uniformity measures are the pullbacks of the
matrix-valued uniformity functionals of Gowers and Hatami under the map $U\mapsto(a\mapsto W_aUW_a^*)$, which we call the Weyl-orbit
embedding. We study the structure of the Weyl-orbit
embedding, and among other results, establish a canonical decomposition of the ambient
matrix-valued uniformity space into uniformity preserving twisted copies of the
quantum uniformity space. The Weyl-orbit
embedding identifies the Clifford hierarchy with Leibman
polynomial maps. This identification yields a representation theoretic characterization of the Clifford hierarchy in terms of
unitary representations of the universal
polynomial groups introduced by the first author and Thom.
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Earth and Planetary Astrophysics
Tidal Rock Grinding as a Source of H2 on Enceladus
Karin I. Oberg, Cara Magnabosco and Nicholas J. Tosca
The
Solar System hosts multiple potentially habitable environments, including the subsurface ocean beneath the icy crust of Saturn's moon Enceladus. This ocean's composition is unusually well constrained thanks to Cassini's observations of Enceladus's south polar plume during multiple flybys. Among the plume's more surprising components is molecular hydrogen (H2), detected in trace amounts. The presence of observable amounts of H2 is intriguing not only because it is difficult to explain through conventional geochemical processes, but also because it could serve as both an energy source for life and a driver of prebiotic organic chemistry. In this study, we explore whether tidally induced rock grinding within Enceladus's core could account for the observed H2. Laboratory experiments show that H2 can be efficiently produced when freshly fractured rock reacts with water. Using these experimentally determined production efficiencies, we estimate H2 generation rates as a function of the fraction of
tidal energy dissipated through rock grinding. Our results suggest that
tidal grinding could plausibly produce the observed levels of H2, with instantaneous production rates potentially exceeding those from radiolysis or serpentinization. However, sustaining such production over geological timescales would require efficient healing of silicate surfaces in the core to allow repeated grinding. Without such healing, tidally induced rock grinding may instead lead to episodic bursts of chemical activity lasting up to millions of years–potentially sufficient to initiate new prebiotic pathways. This transient mechanism would complement the longer-term, lower-energy contributions from serpentinization (over hundreds of millions of years) and radiolysis (over billions of years).
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Chemical Physics
Transferable machine learning of excited-state dynamics with extremal pooling
Cesare Malosso, Wei Bin How, Gonzalo Díaz Mirón et al. (+2 more)
Photochemical processes govern phenomena ranging from
solar energy conversion and atmospheric chemistry to
vision and photosynthesis. Accurate simulation of these processes requires modeling excited-state potential energy surfaces, often involving chemical reactions, tasks that remain computationally prohibitive for extended systems and long timescales using traditional ab initio methods. Machine learning interatomic potentials have revolutionized ground-state simulations, but their extension to excited states faces fundamental challenges: standard architectures assume energy extensivity, an assumption that fails for excited states. Here, we present a size-intensive machine-learning framework for excited-state dynamics based on extremal pooling of predicted atomic HOMO and LUMO contributions. Trained exclusively on excitations energies and forces, the architecture learns interpretable atomic-level contributions that encode physical information on the extent of electron localization. We demonstrate this framework on the photoexcited solvated electron in
liquid water, a paradigmatic problem in radiation chemistry leading to competing pathways involving both hydrogen-atom dissociation and
proton-coupled electron transfer. The model not only reproduces the relevant chain of reactions and product species that form during excitation, but also allows one to explicitly study the dynamics of the solvated electron in quantitative agreement with previously reported Restricted Open-Shell Kohn-Sham calculations, while enabling excited-state simulations of periodic systems at length and time scales inaccessible to the reference electronic-structure method. This work establishes a general strategy for machine learning-driven excited-state dynamics applicable to diverse photochemical systems, from molecular chromophores in solution to extended condensed-phase systems.
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All authors Cesare Malosso, Wei Bin How, Gonzalo Díaz Mirón, Ali Hassanali, Michele Ceriotti
High Energy Physics (Theory)
Flux Quantization on 10D Type IIA Superspace via Cyclification from 11D
Grigorios Giotopoulos and Hisham Sati
We produce the dimensional reduction to 10D IIA supergravity (SuGra), via cyclification, of the remarkable result that full 11D SuGra is put on shell just by imposing the duality-symmetric Bianchi identities on C-field super-flux densities over supertorsion-free superspace. Generally, we highlight that when duality-symmetric superspace Bianchi identities are characterized by Whitehead bracket $L_\infty$-
algebras $\mathfrak{l}\mathcal{A}$ of a classifying space $\mathcal{A}$, their dimensional reduction is characterized by the cyclic loop space $\mathrm{Cyc}(\mathcal{A})$. We promote this to a general mechanism of dimensional reduction on super-spacetime, compatible with the global (infrared) completion of supergravity theories by flux quantization in non-abelian
cohomology with coefficients in $\mathcal{A}$ and $\mathrm{Cyc}(\mathcal{A})$, respectively. In the case of 11D SuGra, the characteristic $L_\infty$-
algebra is $\mathfrak{l}S^4$ and hence we obtain that full on-shell 10D IIA SuGra is equivalent to $\mathfrak{l}\mathrm{Cyc}(S^4)$-Bianchi imposed identities on NS/RR super-flux densities over supertorsion-free 10D super-spacetime. This implies that any space which is $\mathbb{R}$-rationally equivalent to $\mathrm{Cyc}(S^4)$ classifies an admissible flux quantization law, which provides a global completion of 10D IIA SuGra that admits oxidation to 11D.
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