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Physics

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Monday 13 July

Mathematical Physics

On The Eigenvalue Rigidity of the Laguerre Unitary Ensemble

Chenhao Lu and Xiaolu Yue

In this paper, we establish an optimal global rigidity estimate for the eigenvalues of the Laguerre unitary ensemble. Using the central limit theorem, we first construct a random measure via the eigenvalue counting function and then prove its convergence to a Gaussian multiplicative chaos measure, which yields the desired rigidity result. To prove this convergence, we apply a sufficient condition due to Claeys et al.[7] and carry out an asymptotic analysis of the corresponding exponential moments.
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High Energy Astrophysical Phenomena

Radio and X-ray flux rebrightening six years after outburst in a partially-obscured extreme changing-look AGN

Tianyao Zhou, Xinwen Shu, Lei Yang et al. (+14 more)

SDSS J1548+2208 is a unique partially-obscured nuclear transient that exhibits multiwavelength outbursts in mid-infrared, X-ray and radio. We present the results from multiwavelength photometric and spectroscopic follow-up observations with a time span of ~2500 days since its discovery. We find that the mid-infrared and X-ray emission (with a hard X-ray spectrum) are still in a high flux level relative to the pre-flare state, suggesting a sudden increased, and possibly long-sustained accreting activity from central black hole. This is supported by the slowly-evolving high-ionization coronal lines. The mid-infrared color turns blue slowly in the rising phase, which is distinct from stellar tidal disruption events (TDEs). All these properties point to the origin of outbursts from an extreme changing-look AGN and the scenario with a normal TDE seems disfavored. The radio spectral energy distribution (SED) in ~0.65-15 GHz is unusual, displaying a double-peak feature with distinct variability characteristics. In addition, we find evidence for the late-time radio rebrightening more than six years since the initial outburst, as well as a possibly new X-ray flare, though the significance for the latter is not high. The peculiar radio flux and SED evolution could be explained by a nascent outflow expanding into and shocking circumnuclear diffuse medium filled by denser clouds. In this case, SDSS J1548+2208 represents a rare changing-look AGN which can launch radio outflows. Continued multiwavelength observations are required to map the dust and gas distribution on pc-scales, providing new insights into the environmental properties that could regulate AGN changing-look phenomenon.
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All authors Tianyao Zhou, Xinwen Shu, Lei Yang, Tao Wu, Luming Sun, Yibo Wang, Guobin Mou, Ning Jiang, Wenjie Zhang, Hucheng Ding, Fabao Zhang, Yujun Yao, Liming Dou, Yogesh Chandola, Ningyu Tang, Jianguo Wang, Tinggui Wang

High Energy Astrophysical Phenomena

AT2019ijn: a fast-rising, slow-decaying blue optical transient with exceptionally bright radio emission

Hucheng Ding, Xinwen Shu, Luming Sun et al. (+9 more)

We report the discovery of a peculiar optical transient, AT2019ijn, occurred in the nuclear region of a dwarf galaxy at z=0.273. It rises rapidly to peak at a luminosity of Mg=-21.1 in 5 days, followed by a slow decline over more than a month, during which the optical emission has a persistently high blackbody temperature of T_BB~1.5-1.6x10^4 K. The radio emission is exceptional which peaks at 640 days after optical discovery with a high luminosity of 2x10^31 erg/s/Hz. The peak radio luminosity is at least two orders of magnitude brighter than known radio-bright fast blue optical transients and supernova explosions at similar epochs, but comparable to jetted tidal disruption events. The luminous and long-lasting radio emission with a late-time peak can be explained by an off-axis relativistic jet with a viewing angle of ~40 deg. We discuss possible origins for AT2019ijn and favor a jetted tidal disruption event involving an intermediate-mass black hole of ~10^5 Msun, although a jetted magnetar model cannot be fully ruled out. AT2019ijn represents a new class of relativistic optical transients that highlights the importance of radio surveys for discovering off-axis jetted events.
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All authors Hucheng Ding, Xinwen Shu, Luming Sun, Liangduan Liu, Lei Yang, Yunwei Yu, Xueguang Zhang, Ying Gu, Fangkun Peng, Fabao Zhang, Zhumao Zhang, Ningyu Tang

High Energy Astrophysical Phenomena

Two Earliest Optical-UV Tidal Disruption Events Hidden in the SDSS DR7 Catalog Unveiled by the Transformer-Based Spectrum Classifier

Ranfang Zheng, Zheyu Lin, Xu Kong et al. (+3 more)

Optical spectroscopic features are decisive in the current identification of optical-UV tidal disruption events (TDEs). Regarding that the TDE estimated occurrence rate is $10^{-5}-10^{-4}$ galaxy$^{-1}$ yr$^{-1}$ by both theoretical and observational methods, large optical spectroscopic catalogs with >10$^5$ galaxy spectra can include some serendipitous spectra with TDE spectroscopic features, which can be found after building a useful selection method. We hereby introduce a principal component analysis enhanced Transformer TDE spectrum classifier which achieves a precision of 0.88 and a recall of 0.99 on our evaluation dataset, and report its inspiring discoveries in the widely-used SDSS DR7 catalog: two newly discovered TDEs and one reported likely TDE. For SDSS J124225.39+642919.0, we confirm the presence of a UV transient in GALEX catalog when the spectrum was taken, and its occurrence time should be earlier than the spectrum observation time, MJD < 52316 (February 11, 2002), making it the earliest optical-UV TDE discovered by now. For SDSS J152459.70+045423.1, its spectrum matches all features of the TDE-H+He spectrum, and was taken during an optical outburst recorded by the Catalina Real-time Transient Survey. The start of this outburst lies in 54269 < MJD < 54476 (June 18, 2007 - January 11, 2008), making it one of the earliest among the reported optical TDEs. The discovery of two new TDEs highlights the power of machine-learning based classifiers in digging out buried treasures in large-volume catalogs, and marks a new method for discovering optical-UV TDEs.
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All authors Ranfang Zheng, Zheyu Lin, Xu Kong, Ran Song, Dezheng Meng, Lulu Fan

Nuclear Theory

The petit four of color-superconducting phases in proto-neutron star evolution

Selina Kunkel, Ishfaq Ahmad Rather, Hosein Gholami et al. (+2 more)

At high densities and moderate temperatures, hadronic matter is expected to undergo a first-order phase transition into a color-superconducting (CSC) state. A proto-neutron star describes the earliest evolutionary stages during the first seconds to minutes after core-collapse supernovae and therefore has the potential to assess the appearance of CSC phases at such high densities and moderate temperatures. To address this, we incorporate proto-neutron star conditions, considering neutrino-trapped and neutrino-transparent ones, into the equation of state including color-superconducting phases in a recently developed RG-consistent NJL model. Since the total baryon number of a proto-neutron star is conserved during its later evolution, tracking stellar configurations from an initial mass of the hot proto-neutron star to the final cold neutron star along isolines of baryon number allows us to investigate whether color-superconducting phases can form at any point along this trajectory. By mapping this multidimensional transition in the hot furnace of a core-collapse supernovae cooling from a neutrino-trapped birth state to a cold, neutrino-transparent final state, we reveal four distinct core evolution scenarios-our "petit four" of proto-neutron star evolution: a delayed collapse from the CSC phase to a black hole, a persistent CSC phase, a vanishing CSC phase, and a fleeting CSC phase. For our specific parameterization of the hadronic and the CSC equation of state, we find that a stable color-superconducting phase can only be sustained in the final cold neutron star for a narrow, high-mass region.
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All authors Selina Kunkel, Ishfaq Ahmad Rather, Hosein Gholami, Marco Hofmann, Jürgen Schaffner-Bielich

High Energy Physics (Phenomenology)

An improved moment QCD sum rule

Jin-Peng Zhang, Xu-Liang Chen and Wei Chen

QCD sum rules are among the most important non-perturbative tools in hadron physics, with the Laplace sum rule (LSR) and moment sum rule (MSR) being the two most commonly used formulations. Despite their widespread application, both approaches have significant shortcomings: the LSR relies on subjective criteria – namely OPE convergence and pole dominance – to constrain the parameter space, while the conventional MSR cannot extract the coupling constant of the interpolating current. More critically, the ground-state masses obtained from these two methods are often inconsistent. In this work, we propose an improved moment sum rule (IMSR) framework that resolves these issues simultaneously. Our method explicitly incorporates quark-hadron duality, which introduces the approximation condition on the OPE side and provides a natural a posteriori constraint on the parameters. We impose rigorous dependence conditions on the unphysical parameters $(Q^2_0,n)$ to quantify and control their influence. As a result, our framework uniquely determines both the optimal value of the duality parameter and the ground-state mass, without invoking any ad hoc or subjective criteria. It also allows for the simultaneous extraction of the current coupling. Applying the IMSR to a pseudoscalar $ud\Bar{d}\Bar{s}$ tetraquark system, the results are in excellent agreement with our previous LSR analyses, validating the effectiveness of the proposed scheme. The IMSR method substantially enhances the robustness and reliability of QCD sum rules, effectively eliminating the subjectivity that has long plagued conventional formulations.
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Strongly Correlated Electrons

Stripe-Ordered Altermagnetism Emerging from Correlation-Driven Spin-Density-Wave Instability

Zenghui Fan, Jingyao Meng and Tianxing Ma

Altermagnetism is conventionally identified within the paradigm of collinear antiferromagnets. Its potential realization within other spin instabilities, such as a spin-density wave (SDW), remains a fundamentally compelling open question. Here, we combine Hartree-Fock mean-field and unbiased determinant quantum Monte Carlo methods to investigate a minimal Hubbard model relevant to iron pnictides. We reveal a novel $d_{xy}$-wave stripe-ordered altermagnetic (SOAM) insulating phase driven fundamentally by the correlation-induced $(\pi,0)$ SDW instability. Within this phase, an introduced uniaxial staggered electric potential alters the underlying symmetry: it breaks the original combined time-reversal and spatial translation symmetry ($T_{d}\mathcal{T}$) and retains a combined time-reversal and mirror invariance ($M\mathcal{T}$), thereby unlocking the pronounced nonrelativistic spin splitting. Crucially, the exact finite-size scaling from our determinant quantum Monte Carlo simulations confirms that this correlation-driven SOAM phase stably survives at accessible finite temperatures. Our study pushes the frontier of altermagnetism beyond the conventional antiferromagnetic paradigm into the realm of SDW instability, advancing the fundamental understanding of altermagnetism in strongly correlated electron systems.
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Earth and Planetary Astrophysics

Evolution and Observable Properties of Rocky Planet Atmospheres

Marie-Luise Steinmeyer, Lena Noack, Philipp Baumeister et al. (+9 more)

The atmospheric composition of rocky exoplanets offers an important tool for constraining the properties of the interior of this type of planet, beyond what is possible from measurements of their mass and radius alone. However, the interpretation of these observations requires an understanding of the complex interplay of a larger number of coupled planetary and atmospheric processes. This review provides an overview of the current state of knowledge regarding rocky exoplanet atmospheres, beginning with their formation and escape mechanisms. We specifically highlight the importance of long-term interaction between the atmosphere, the surface, and the interior on rocky planets. Furthermore, this review addresses the influence of biological activity and photochemical reactions on the atmospheric compositions. Consequently, establishing how these different processes contribute to shaping the atmospheres of rocky exoplanets during their evolution is fundamental for the characterization of these planets with future space missions and ground-based surveys.
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All authors Marie-Luise Steinmeyer, Lena Noack, Philipp Baumeister, Keiko Hamano, Michael J. Way, Doris Breuer, Kanako Seki, Caroline Brachmann, Fabrice Gaillard, Manuel Scherf, Svetlana V. Berdyugina, Brice-Olivier Demory

Statistical Mechanics

Harnessing finite-size effects to gauge aging in the $2D$ Ising model

Dustin Warkotsch, Malte Henkel and Wolfhard Janke

The relaxation behavior towards equilibrium of the $2D$ Ising model with nearest-neighbor interactions has been studied with focus on the two-time autocorrelator $C(t,s)$. Finite-size effects affecting the growing magnetic domains lead to the saturation of $C(t,s)$ with a distinct plateau of height $C_{\infty}^{(2)}(s,L)$ scaling algebraically with waiting time $s$ and lattice size $L$. These scaling relations are used to produce precise estimates for the autocorrelation exponent $\lambda$ and dynamical exponent $z$ with deliberately small lattices. Treating smooth domain walls in a similar manner to the lattice boundaries, their effect on $C(t,s)$ can be understood as premature finite-size phenomenon, extending our ansatz to systems not yet in equilibrium.
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Optics

NaBiF$_4$: Er$^{3+}$, Yb$^{3+}$ upconversion particle as a multi-functional bio-marker

Atanu Ghosh, Krishna Kumari Swain, Agniva Das et al. (+6 more)

Lanthanide-doped upconversion particles (UCPs) have revolutionized optical bioimaging platforms because of their excellent photostability, non-toxicity, and utilization of near-infrared excitation, which facilitates deep tissue penetration with negligible autofluorescence. However, it remains a challenge to achieve high-contrast and sub-diffraction imaging in noisy biological media, without using a high-power laser. Here, we report various protocols applied to bismuth-doped UCPs address some of these challenges. Compared to the photoluminescence (PL) emission of the regular Yttrium doped UCPs, we observe a three-fold increment in the quantum yield of the overall emission of bismuth-UCPs, and a four-fold increment, specifically, in red emission. Leveraging this advantage, we devise a protocol employing two infrared wavelengths, 975 nm and 1064 nm, to selectively control the PL emission. Interestingly, our results reveal two distinct regimes in which PL can be systematically quenched or enhanced, by adjusting the 975 nm laser power. We model the overall dynamics as a simplified stimulated emission depletion process involving three energy levels. In addition, the particle has a thickness under sub-diffraction, shows optical trapping ability, and potential of surface functionalization to enable specific conjugation with diverse biospecimens. These studies establish bismuth doped UCPs as an excellent candidate in accomplishing advanced biomarker operating with enhanced signal-to-noise ratio and sub-diffraction imaging capabilities.
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All authors Atanu Ghosh, Krishna Kumari Swain, Agniva Das, Mrutyunjaya Rath, Snigdhadev Chakraborty, Bipeen Kumar, Yamini Selvam, Siddharth Dhomkar, Basudev Roy

Materials Science

Capturing the calendering U-shape in lithium-ion electrode thermal conductivity

Julius Störk

Calendering is a key manufacturing step in lithium-ion electrode production, increasing volumetric energy density by reducing electrode porosity. Its effect on through-plane effective thermal conductivity, however, can be non-monotonic: measurements of graphite-based anodes show an initial decrease in thermal conductivity during early calendering followed by recovery at higher compaction. Conventional porosity-based effective-medium closures cannot reproduce this U-shaped behaviour. We develop a calendering-aware extension of the Zehner–Bauer–Schlünder model that combines a Knudsen-corrected porous-medium baseline with a compression-indexed contact contribution. For graphite electrodes, the model represents the competing effects of increasing particle contact and calendering-induced reorientation of anisotropic graphite particles, which initially reduces favourable through-plane heat-transport pathways. For quasi-isotropic NMC cathodes, the observed response is instead captured through process-dependent contact-network evolution. Across 27 calendering states spanning thin and thick graphite anodes and NMC622 and NMC811 cathodes, the proposed closure reduces the mean absolute percentage error from 31.1% for the zero-fit reference model to 4.5%. The result shows that incorporating process-dependent microstructural evolution is necessary to capture the measured conductivity minimum. Validation across additional electrode formulations, thicknesses, and chemistries remains necessary to assess transferability.
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General Relativity and Quantum Cosmology

Dynamics and observational signatures of warm Dirac-Born-Infeld inflation with nonminimal derivative coupling

Run-Qing Zhao, Xiao-Min Zhang, Peng-Cheng Chu et al. (+1 more)

This paper investigates a warm Dirac-Born-Infeld (DBI) inflationary model with nonminimal derivative coupling (NMDC) to gravity, where the inflaton kinetic term interacts with the Einstein tensor, thereby improving the effective gravitational friction. This model seamlessly integrates the noncanonical DBI kinetic structure, the NMDC-induced gravitational friction, and thermal dissipation. We formulate the background evolution equations along with the corresponding slow-roll stability conditions, leading to analytic results for the scalar spectral index $n_s$ and the tensor-to-scalar ratio $R$. By applying these results to power-law potentials with $n=2$ and $n=4$, the model parameter space is constrained using the Planck 2018 data. The findings indicate that the interaction between NMDC-induced gravitational friction and thermal dissipation effectively modulates $n_s$ and significantly expands the viable parameter space. In the $(n_s,R)$ plane, the predictions for $N=50$ fall within the 95% confidence-level region, while those for $N=60$ extend into the 68% confidence-level region and approach the observationally preferred central values. For the representative parameter choices examined, the tensor-to-scalar ratio is notably suppressed, generally within the range $10^{-8}\lesssim R\lesssim10^{-5}$. Moreover, the combined damping mechanism relaxes the slow-roll condition related to $\eta$ and limits the inflaton field excursion, thus addressing the $\eta$ problem without incurring super-Planckian field variations. These results indicate that warm DBI inflation with NMDC offers a theoretically coherent and observationally viable inflationary model, showcasing the complementary effects of thermal dissipation and enhanced gravitational friction in the context of modified gravity.
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All authors Run-Qing Zhao, Xiao-Min Zhang, Peng-Cheng Chu, Yun-Cai Feng

Superconductivity

Microscopic equivalence of the vortex-entry current and the depairing current in a superconducting thin-film strip

Takayuki Kubo

The vortex-entry current density $J_{\rm v}$ of a superconducting strip is usually defined, within phenomenological Pearl–London theory, as the current density at which the edge barrier for vortex entry disappears. In that approach, $J_{\rm v}$ depends on a short-distance core cutoff introduced by hand, and its temperature dependence cannot be determined within the same framework. To remove this cutoff ambiguity and determine the temperature dependence, one needs a microscopic calculation of the vortex-entry current. Nevertheless, such a microscopic calculation has never been carried out. Here, we formulate and solve this problem for an ideal homogeneous dirty-limit superconducting thin-film strip at zero applied field, with self-field effects neglected. Vortex entry is treated as the loss of local stability of the vortex-free current-carrying state. The calculation uses the fixed-current Gibbs functional of Usadel theory, which is valid over the full temperature range $0<T<T_c$, and examines both spatially uniform and nonuniform perturbations. The microscopic calculation shows that the condition for disappearance of the vortex-entry barrier is identical to the depairing condition. The central result is not merely that two current densities have the same value. The criterion for disappearance of the vortex-entry barrier and the depairing criterion are not independent conditions. Both identify the same loss of local stability of the vortex-free current-carrying state, namely, the same spinodal. Consequently, $J_{\rm v}(T)=J_{\rm dp}(T)$ for all $0<T<T_c$. This result determines the temperature dependence of $J_{\rm v}$, removes the Pearl–London core-cutoff ambiguity, and establishes the microscopic equivalence of the vortex-entry and depairing current criteria.
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Quantum Physics

Quantum Simulation of Strongly Correlated Fermion-Phonon Models in Circuit QED

Tim Bode, Riccardo Roma, Stefan Schmitz et al. (+4 more)

Gate-based digital quantum simulations offer an exciting new paradigm for studying the many-body physics of strongly correlated systems. In this context, electron-phonon models are challenging for qubit-only quantum simulators, as bosonic degrees of freedom require costly finite-dimensional encodings. Here, we elaborate on an alternative approach based on a digital-analog circuit QED architecture, where fermions are encoded in transmon qubits while bosons are represented directly by microwave resonators. The central building block of this framework is a qubit-resonator Rabi gate that emulates strong electron-phonon coupling and can be implemented through a sequence of resonant Jaynes-Cummings gates interleaved with layers of single-qubit rotations. Using this Rabi gate as the fundamental unitary operation, we construct quantum circuits for the Hubbard-Holstein and Yukawa-Sachdev-Ye-Kitaev models, which describe, respectively, strongly correlated electrons coupled to phonons and phonon-mediated interactions among Majorana fermions. We further demonstrate how nonclassical phonon physics and signatures of quantum chaos in these models can be probed through circuit simulations, and develop measurement and variational protocols tailored to near-term superconducting quantum hardware.
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All authors Tim Bode, Riccardo Roma, Stefan Schmitz, Alessandro Ciani, Dmitriy S. Shapiro, Dmitry Bagrets, Frank K. Wilhelm

Quantum Physics

States dressing analysis in a transmon-transmon-bus system

P.A. Gladilovich, R.A. Migdisov, A.V. Sabluk et al. (+5 more)

The multi-qubit gates fidelity of superconducting quantum processors can be limited due to the dressing of computational states by noncomputational ones. Here, we experimentally and analytically investigate a transmon-transmon-bus system where the computational states dressing is tunable over a broad range. We estimate the dressing using three methods: a full three-element model, an effective mode approach, and an unperturbed mode approach. The obtained results highlight the importance of the accurate estimation and control of the computational states dressing in order to optimize gates on superconducting platform.
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All authors P.A. Gladilovich, R.A. Migdisov, A.V. Sabluk, P.S. Burtsev, N.N. Abramov, N.Y. Rudenko, V.I. Chichkov, N.A. Maleeva

Earth and Planetary Astrophysics

Discovering and Characterising Exoplanets and Ultracool Dwarfs with the Square Kilometre Array

Robert D. Kavanagh, Juan B. Climent, Philippe Zarka et al. (+14 more)

The majority of the Solar System planets are sources of bright radio emission, driven by energetic electrons trapped within each planet's magnetic field. Detection of this emission from exoplanets provides a unique opportunity to characterise their magnetic fields, which is key to determining the atmospheric evolution of exoplanets. However, a conclusive detection of radio emission from an exoplanet remains at large, primarily due to a lack of sensitivity at low radio frequencies. On the other hand, planet-like radio signatures have been detected on objects called ultracool dwarfs (UCDs) for over two decades. UCDs are of comparable sizes to Jupiter, but are more massive. They also possess similar interior structures to Jupiter, the region where magnetic fields are generated. Therefore, UCDs are ideal targets to study to advance our understanding of how magnetic fields manifest at planetary scales. In this Chapter, we outline the revolutionary role that the Square Kilometre Array will play in the study of exoplanets and UCDs. We anticipate that it will facilitate the first detection of radio emission from giant exoplanets with strong magnetic fields, and will deliver thousands of detections of UCDs within a few hundred parsecs. Combined with very long baseline interferometry, we also expect that astrometric monitoring will enable the detection of planets of a few Earth masses orbiting nearby radio-emitting UCDs. These findings will open a new window into how planets form and evolve in extrasolar systems.
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All authors Robert D. Kavanagh, Juan B. Climent, Philippe Zarka, Joseph R. Callingham, Yuka Fujii, Corentin K. Louis, Laurent Lamy, Mayank Narang, J. Sebastian Pineda, Harish K. Vedantham, Sanne Bloot, Jean-Mathias Grießmeier, Jose Carlos Guirado, Simranpreet Kaur, T. Joseph W. Lazio, Miguel Pérez-Torres, Alice Zurlo

High Energy Physics (Phenomenology)

Unitarization Schemes for High-Energy Elastic Scattering

E. G. S. Luna

We examine key features of the eikonal and $U$-matrix unitarization schemes and apply both frameworks to investigate the high-energy behavior of the elastic scattering amplitude, considering input amplitudes whose asymptotic behavior is driven exclusively by Pomeron exchange. Particular attention is devoted to assessing how the extracted Pomeron parameters depend on the assumed trajectory form. In this context, we compare linear and nonlinear Pomeron trajectories, evaluating their impact on the phenomenological description of the data and on the stability of the fitted parameters.
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Mesoscale and Nanoscale Physics

Purcell enhanced and blinking free single photons from InAs/GaAs quantum dots in deterministically placed circular Bragg gratings

Peter Gschwandtner, Quirin Buchinger, Krishna Chand Maurya et al. (+11 more)

The development of efficient, deterministic, and tunable single-photon sources is a cornerstone for the realization of long-distance quantum communication, quantum repeaters, and photonic quantum computing technologies. In this study, we demonstrate a bright, charge-tunable single-photon source in the 900 nm wavelength range based on InAs quantum dots (QDs) embedded in a p-i-n doped GaAs membrane, which shows blinking free emission. We use a modified circular Bragg grating (CBG) as a micro-resonator. By adding fourfold symmetric bridges in a labyrinth-like geometry, we provide a conductive pathway to the central disk, thereby enabling electrical contact to the QD while maintaining high Purcell enhancement and photon extraction efficiency (PEE). For the negative trion (X-), we demonstrate a lifetime of $44.3 \pm 0.2$ ps - corresponding to a Purcell factor of $18.0 \pm 0.7$ and a PEE of $68.1% \pm 3.1$ %. Furthermore, the device is blinking-free with very low multi-photon contribution, evidenced by a second-order autocorrelation value $g(2)(0) < 0.017 \pm 0.015$. By applying a vertical diode bias, we demonstrate precise charge-state control, resolving distinct emission plateaus ranging from the single negatively charged trion ($X^-$) to triply negatively charged excitons ($X^{3-}$). These results showcase a robust architecture that simultaneously provides high efficiency, high repetition rates, and deterministic charge control, fulfilling key requirements for the next generation of quantum network hardware.
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All authors Peter Gschwandtner, Quirin Buchinger, Krishna Chand Maurya, Mohamed Helal, Barbara Souza Damasceno, Ravindra Kumar, Hyemin Kim, Ievgen Brytavskyi, Silke Kuhn, Arne Ludwig, Dirk Reuter, Yong-Hoon Cho, Tobias Huber-Loyola, Sven Höfling

Quantum Physics

A diode nanocavity for fast, efficient and tunable emission of highly entangled photon pairs and Fourier-transform-limited single photons

Ievgen Brytavskyi, Thomas Oberleitner, Christian Weidinger et al. (+16 more)

Deterministic sources of entangled photon pairs and indistinguishable photons are expected to play a key role in photonic quantum technologies. Semiconductor quantum dots are promising candidates due to their on-demand emission and compatibility with nanophotonic structures. However, current implementations face trade-offs between extraction efficiency, Purcell enhancement, as well as charge noise that causes blinking and degrades indistinguishability. Here we demonstrate a tunable nano-optoelectronic device based on a quantum dot embedded in a p-i-n diode circular-Bragg-grating-resonator and featuring extraction efficiencies up to 0.55(6) and Purcell-factor of $\sim$8. The device generates wavelength-tunable entangled photon pairs with suppressed blinking and raw (corrected) concurrence > 0.89 (0.91) over a range of 1.6 nm. The very same source also emits single, nearly Fourier-limited and highly indistinguishable photons with raw (corrected) $\mathcal{V}_{\text{HOM}}$ = 0.951(4) (0.988(6)). These results demonstrate a viable platform for semiconductor quantum photonics.
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All authors Ievgen Brytavskyi, Thomas Oberleitner, Christian Weidinger, Maximilian Aigner, Gabriel Undeutsch, Tobias Steindl, Johannes Reindl, Ailton Garcia Jr., Melina Peter, Christian Schimpf, Santanu Manna, Michele B. Rota, Quirin Buchinger, Sven Höfling, Tobias Huber-Loyola, Rinaldo Trotta, Tobias M. Krieger, Eva Schöll, Armando Rastelli

Quantum Physics

AtomFlow: An End-to-End FPGA-Based Control Architecture for Neutral Atom Quantum Computers

Xiaorang Guo, Jonas Winklmann, Vengkeat Chea et al. (+1 more)

Neutral Atom Quantum Computing (NAQC) is an emerging modality for scalable quantum computation, valued for its long coherence times and the naturally identical atomic qubits. However, one of the main drawbacks is its slow execution rate, dominated by lengthy classical processing tasks, such as fluorescence imaging, cooling, and atom rearrangement. We address this bottleneck with AtomFlow, a field-programmable gate array (FPGA)-based control architecture that consolidates fluorescence-image analysis and a newly developed atom-rearrangement algorithm onto a single Zynq UltraScale+ device. By co-locating the two stages on the same board and emitting rearrangement moves in a streaming fashion as soon as they are computed, AtomFlow eliminates the round-trip latency of conventional host-mediated pipelines. Evaluated on a 16x16 atom array, AtomFlow achieves an end-to-end latency of 25.3 ms with a first-move latency of 4 ms and an average move generation of 1 ms. Furthermore, our scalability analysis demonstrates that the architecture can readily support larger atom arrays within a single-board resource budget.
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All authors Xiaorang Guo, Jonas Winklmann, Vengkeat Chea, Martin Schulz

High Energy Astrophysical Phenomena

Superdiffusion of cosmic rays in the vicinity of their accelerators and the resulting $\gamma$-ray emission

Zhaodong Shi, Guangwei Wang and Rui-zhi Yang

We study the distribution of cosmic rays (CRs) in the vicinity of their accelerators, assuming that the transport of CRs in the interstellar medium surrounding the accelerators is described by the superdiffusion, beyond the normal diffusion. We find that the superdiffusivity, which is characterized by the superdiffusion parameter $\alpha$, impacts significantly the distribution of CRs. For impulsive injection, the CR distribution behaves a constant radial profile, except with a power-law tail for $\alpha < 2$ or a Gaussian tail for $\alpha=2$ at large distance, $r$, from the accelerators. For stationary injection, the radial profile of CR protons tends to being proportional to $r^{\alpha - 3}$, while that of CR electrons can deviate from the $r^{\alpha - 3}$ profile, due to their severe energy losses. We also compute the $\gamma$-ray emission, produced by the interactions of CRs with ambient gas and radiation fields, within 100 pc regions around the accelerators. We find that by investigating the $\gamma$-ray morphology, we can distinguish the superdiffusion from the normal diffusion with present and next-generation imaging air Cherenkov telescopes.
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Strongly Correlated Electrons

Fractionalized metals from doped anyons: Application to tMoTe2

T. Senthil

A fluid of mobile anyons may arise naturally when a Fractional Quantum Anomalous Hall (FQAH) state is doped. Motivated by recent experiments on twisted $MoTe_2$, we study metallic phases obtained by doping the $\sigma_{xy} = 2e^2/3h$ state. We propose that the high-resistivity metal observed adjacent to this FQAH state is a $Z_3$ Orthogonal Metal: a non-Fermi liquid with sharp charge $1/3$ fermionic quasiparticles coupled to a discrete $Z_3$ gauge field but with no sharp electronic quasiparticle. For a dilute gas of three species of charge-$1/3$ anyons with $\pi/3$ statistics, we construct two $U(3)$ symmetric $Z_3$ Orthogonal Metals, distinguished by whether the gapless fermions transform as $SU(3)$ triplets or singlets. We show that these states naturally yield large electrical resistivities even when the fractionalized quasiparticles are in a good metallic regime. Pairing of the charge-$1/3$ fermions produces an ordinary charge-$2e$ superconductor, smoothly connected to a BCS state but obtained through an intrinsically fractionalized normal state. We discuss experimental signatures of the idea that the normal metallic state in the lightly doped $2/3$ state may have fractionalized charge carriers.
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Quantum Physics

Strong Zero Modes in Supersymmetry-Inspired Quantum Circuits

Alberto Zorzato, Pietro Richelli, Jiri Minář et al. (+1 more)

We investigate discrete dynamics in quantum circuits with gates corresponding to the S-matrix of a supersymmetric 1+1D quantum field theory. We show that for a brick-wall configuration such circuits support both localized and delocalized dynamically conserved operators known as strong zero modes (SZM), the number of which depends on the parameter regime. We demonstrate that, while some of the SZM remain localized at boundaries, other SZM propagate ballistically, guided by a choice of circuit parameters. Such propagation can be explained by a strong Dzyaloshinskii Moriya term appearing in the dynamics. We describe how to exploit propagating SZM for quantum information transport and discuss the robustness to various types of noise.
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All authors Alberto Zorzato, Pietro Richelli, Jiri Minář, Kareljan Schoutens

Classical Physics

Surface charge density of current-carrying conductors: An exact analytical solution for infinitely thin wires of arbitrary shape

Roberto Merlin

An exact asymptotic expression is derived for the surface charge density associated with a steady current in closed loops or wire segments of infinitesimal cross section connected to a battery. Except for vanishingly thin boundary layers at the ends of the wire, and irrespective of the conductor shape, the charge density varies linearly with arc length, as does the electrostatic potential along the curve. This proportionality generalizes earlier results and provides a clear physical picture of charge accumulation in electrical circuits.
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Mesoscale and Nanoscale Physics

Theory of phonon-induced spin relaxation in a structured phononic reservoir

Raseeb F. Haroon and Paweł Machnikowski

By combining Markovian and non-Markovian open quantum system theory with finite-element simulations, we develop a theory of electron spin relaxation in a structured phononic reservoir. This problem is crucial for understanding spin dynamics in hybrid systems involving mechanical modes, as well as for the design of devices combining spin degrees of freedom with photonic and phononic architectures, where the phonon density of states is modulated in the relevant spectral range corresponding to moderate magnetic fields. Taking a QD in a phononic waveguide as a representative and technologically relevant example, we show that spin relaxation in such environments is much more complex than in bulk. While the relaxation rates are several times to an order of magnitude higher than in bulk, there are parameter windows where the relaxation is suppressed by many orders of magnitude due to gaps in mode dispersion and selection rules imposed by mode symmetry. At the border between these two sectors, van Hove singularities in phonon dispersion lead to singularities in relaxation rates, for which we develop power-law scaling and develop a non-Markovian description of the dynamics, revealing polaronic dressing of the spin into slow acoustic modes.
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Mathematical Physics · Cross-listed from math.AP

From diffusion to transmission via EDP-convergence: a paradigmatic multiscale limit

Thomas Frenzel and Alexander Mielke

We consider nonlinear diffusion equations on an interval where the diffusion coefficient in a small region near the center is scaled such that it approximates a transmission condition at a membrane. While the limiting behavior of the solutions is well-understood, we study the convergence in the sense of the energy-dissipation principle (EDP) of associated gradient structures given in terms of a free energy and a dissipation potential. EDP-convergence provides a uniquely specified limiting gradient structure that reformulates the transmission condition in terms of an effective kinetic relation for the membrane, which relates the jump of the chemical potential and the flux through the membrane. We show how \AAA properties of the chosen free energy and the mobility of small-scale diffusion migrate to the effective kinetic relation. A surprising result is that starting from the linear Onsager relation of Otto's gradient structure for the linear diffusion equation, one obtains an exponentially growing kinetic relation, the so-called Marcelin-De Donder kinetic.
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Nuclear Experiment

Search for two-neutrino double electron capture in $^{36}$Ar with the DarkSide-50 detector

DarkSide-50 Collaboration: P. Agnes, I.F.M. Albuquerque, T. Alexander et al. (+82 more)

Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shells and two neutrinos are emitted. We report on the first search for two-neutrino double electron capture in the $\textit{KK}$- and $\textit{KL}$-shells of $^{36}$Ar using the low-radioactivity liquid argon target from underground sources in the DarkSide-50 experiment. No statistically significant excess was observed with approximately 12 ton-day exposure of underground argon (UAr) and, taking into account the $^{36}$Ar isotopic abundance in UAr (0.007%), we set a limit on the half-life of the two-electron capture process in $^{36}$Ar of $T_{1/2} > 9.2 \times 10^{19}$ yr at 90% C.L. The sensitivity of the DarkSide-20k experiment, which will become operational in the next few years, was also evaluated and is expected to increase by a factor $\sim$100 with 10 years of expected operation and assuming the same $^{36}$Ar abundance as in the DarkSide-50 underground argon target.
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All authors DarkSide-50 Collaboration: P. Agnes, I.F.M. Albuquerque, T. Alexander, A.K. Alton, M. Ave Pernas, H.O. Back, G. Batignani, W.M. Bonivento, B. Bottino, S. Bussino, M. Cadeddu, M. Cadoni, A. Caminata, N. Canci, M. Caravati, N. Cargioli, M. Carlini, S. Chashin, A. Chepurnov, S. Davini, S. De Cecco, A. Derbin, D. Díaz Mairena, F. Dordei, G. Fiorillo, D. Franco, F. Gabriele, C. Galbiati, G.K. Giovanetti, M. Gromov, M. Gulino, B.R. Hackett, F. Hubaut, A. Ianni, V. Ippolito, F. Karpeshin, D. Korablev, G. Korga, M. Kuss, M. La Commara, M. Lai, M. Lissia, O. Lychagina, I. Machulin, S.M. Mari, J. Maricic, R. Milincic, M. Morrocchi, V. Muratova, P. Musico, M. Pallavicini, L. Pandola, E. Pantic, E. Paoloni, K. Pelczar, V. Pesudo, A. Pocar, S. Pordes, P. Pralavorio, M. Razeti, A.L. Renshaw, M. Rescigno, D. Sablone, O. Samoylov, S. Sanfilippo, R. Santorelli, C. Savarese, D. Semenov, A. Sheshukov, M. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Stracka, Y. Suvorov, R. Tartaglia, G. Testera, E. Unzhakov, A. Vishneva, B. Vogelaar, M. Wada, Y. Wang, S. Westerdale, M.M. Wojcik, C. Yang, G. Zuzel

Soft Condensed Matter

Colloid recovery from porous structures under ambient flow: enhanced extraction via phoretic and osmotic mechanisms

Jitendra Dhakar, Kapil Upadhyaya and Akash Choudhary

Chemical gradients are widely employed to enhance particle transport in porous media, such as laundry detergency and enhanced oil recovery. Diffusiophoresis and diffusioosmosis refer to the movement of colloid and movement of near-surface fluid in response to electrolyte gradients, respectively. These mechanisms play a crucial role in colloid and drug transport in constricted regions where bulk transport is infeasible. Our earlier work [Tiwari et al., Langmuir 41, 18583 (2025)] has shown that phoretic and osmotic transport in dead-end micro-pores can be controlled by orienting salt gradients into or out of the pores; however, the extent to which this orientation influences large-scale spatiotemporal patterns and colloid extraction is not thoroughly explored. In this work, we study the phoretic and osmotic colloidal extraction from porous structure exposed to an ambient flow. We characterize the impact of solute gradient orientation, such as solute-out (i.e., solute-emitting porous media) and solute-in (i.e., solute-consuming media) modes. The two-dimensional porous structure is made of a number of pillars/fibers arranged in a lattice ordered hexagonal packing with equal spacing. The results from finite-element simulations show that phoretic colloidal extraction exhibits a qualitatively distinct behavior in the two modes: in the solute-out mode, colloids are extracted from the peripheral region of the porous structure, whereas in the solute-in mode, extraction predominantly occurs from the stagnant core. Diffusioosmotic slip on the internal surface of pillars/fibres further amplifies extraction in both modes, with a relatively larger enhancement in the solute-in mode due to internal spatiotemporal flow patterns. Beyond demonstrating the sensitivity of osmotic transport in porous media, these insights can guide enhanced membrane filtration, laundry detergency, and enhanced oil recovery.
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High Energy Physics (Theory)

Superconformal mechanics from N-extended Euler-Calogero-Moser and Calogero models

S.Krivonos and A.Sutulin

In this paper, we considered two-particle variants of the N-extended Euler-Calogero-Moser and Calogero models. Due the translation invariance, the center of mass can be decoupled (together with the corresponding fermions), leaving us with specific superconformal mechanics. Additional bosonic variables (spin variables) can easily be incorporated into the supercharges and the Hamiltonian. In the case of the Euler-Calogero-Moser model, the supersymmetry in the two-particle cases admits an unexpected extension from Osp(N|2) to SU(1,1|N) superconformal symmetry. The case of the Calogero model leads to purely Osp(N|2) superconformal mechanics. The way to get rid of the well-known problems along this path is to have a higher number of fermions present in the system.
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Fluid Dynamics

Feature-based manifold model of actuated wakes

Alicia Rodríguez-Asensio, Guy Y. Cornejo Maceda, Bernd R. Noack et al. (+2 more)

We propose a feature-based reduced-order model to predict the transient dynamics of bluff-body wakes under arbitrary time-varying actuation. Starting point is a control-oriented POD Galerkin modeling which is challenged by incorporating time-varying actuations as a free input. Our model includes three key enablers. First, POD modes are replaced by a more accurate feature-based manifold of same dimension. Second, a state space is distilled from dynamic features which encapsulate time-varying coherent structures. Third, this state space is augmented for the transient actuation response. Thus, a simple analytical manifold dynamics is obtained. The approach is applied to the fluidic pinball at Re=30, a canonical configuration of three identical circular cylinders arranged in an equilateral triangle and immersed in uniform flow under symmetric actuation. The model is validated against several representative actuation scenarios and accurately reproduces the transient dynamics without requiring unsteady training data, providing an interpretable, observable-based and control-oriented framework. The proposed description of actuated bluff-body flows is expected to be generalisable to other configurations.
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All authors Alicia Rodríguez-Asensio, Guy Y. Cornejo Maceda, Bernd R. Noack, Stefano Discetti, Andrea Ianiro