Materials Science
Tunable Flat Bands and magnetism in Triangulene-based Superatomic Graphene
Wenya Zhai, Tingfeng Zhang, Fengkun Chen et al. (+8 more)
Superatomic
graphene platforms host a rich portfolio of flat-band-driven exotic
quantum properties, yet their experimental realization remains challenging. Here, we report the bottom-up on-surface synthesis of superatomic
graphene using phosphorus-doped triangulene as building blocks. Scanning tunneling microscopy and spectroscopy measurements resolve the well-defined honeycomb
lattice of as-fabricated superatomic
graphene and demonstrate the characteristic Dirac band and flat band electronic structures. Density functional theory calculations reveal that the flat bands originate from the in-plane p$_x,_y$-like frontier orbitals of the phosphorus-doped triangulene units, leading to intrinsic half-metallic behavior. Furthermore, oxygen functionalization of the molecular precursor enables deterministic modulation of the electronic structure and
magnetic ordering. This work establishes a general platform for designing correlated
quantum materials with tunable flat band properties.
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All authors Wenya Zhai, Tingfeng Zhang, Fengkun Chen, Xiuqin Lu, Yunlong Xia, Zengfu Ou, Ye Chen, Donghui Guo, Meifang Zhu, Zhengfei Wang, Jingcheng Li
Fluid Dynamics
Restarts of bursts in turbulence in a log-minimal channel
Zengrong Hao and Javier Jiménez
Recent evidence on the sustainment of wall-normal-velocity bursts in wall-bounded
turbulence challenges the classical streak-dependent picture, suggesting that the problem should be approached relying on no a priori knowledge regarding other flow structures. This paper discusses the restarts of bursts in a log-minimal channel within the framework of a linearised Navier-Stokes system with forcing terms encapsulating the nonlinear effects of all other structures. Two generic issues are addressed. The first concerns the conditions for burst-restart-like solutions for the forced linearised system itself. We formulate optimisation problems to understand the 'minimal requirements' for burst restarting. The solutions illustrate three conceptual periods in a typical restarting process, distinguished by the behaviour of spanwise vorticity structures: breakup, counter-rotating catch-up, and co-rotating catch-up. External forces promote this process by breaking up forward-inclined
vortices and merging co-rotating, catching-up
vortices. A quantity termed linearly available energy (LAE) is accordingly proposed to parameterise the restarting process. The second issue concerns the contributory features to the observed burst restarts in real
turbulence. We show that an essential role of nonlinearity in restarting a burst is to increase a decaying state's LAE to a level sufficient for the onset of the subsequent burst. Flow patterns extracted during the restarting stage exhibit breakup and merging effects, both facilitated by nonlinearity. This suggests that the two effects observed in both the linearised models and real
turbulence are manifestations of real flow structures that cause burst restarts.
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High Energy Physics (Phenomenology)
Dyonic lattices, $\theta$-angles and axions in the Standard Model
Rodrigo Alonso, Francesca Chadha-Day, Despoina Dimakou et al. (+2 more)
We investigate the implications of the Witten effect in the Standard Model with a general global gauge group structure and determine the values of the three $\theta$-parameters that lead to distinct families of allowed spectra of dyons. We construct and classify the corresponding dyonic charge
lattices consistent with the Standard Model gauge structure. This approach enables us to re-derive the known global-group–dependent periodicities of the $\theta$ angles and to determine all CP-invariant points in $\theta$-space. The electromagnetic subgroup $U(1)_{\mathrm{em}}$ is shown to arise prior to electroweak
symmetry breaking by factoring out the effect of the anomalous $B+L$ transformations, which reduces the physical $\theta$-parameter space from a three-
torus to a two-
torus. Our phenomenological conclusions include an observation that a discovery of a $U(1)_{\mathrm{em}}$ monopole carrying non-zero electric charge would determine the last remaining unknown parameter of the Standard Model. Lastly we study how $\theta$-space shapes
axion physics with emphasis on the
axion-
photon coupling and show that a single
axion is insufficient to render the Standard Model
vacuum fully CP invariant.
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All authors Rodrigo Alonso, Francesca Chadha-Day, Despoina Dimakou, Yunji Ha, Valentin V. Khoze
Superconductivity
Highly crystalline superconducting TiN resonators grown on thermally reconstructed sapphire
Thomas J. Smart, Marc Neis, Janine Lorenz et al. (+15 more)
High quality crystalline growth of a thin film on sapphire requires sufficient substrate preparation, often achieved via the use of aggressive chemical cleaning. Direct thermal reconstruction of the sapphire substrate via a CO$_2$
laser beam may allow for an alternative way to prepare the substrate for epitaxy without the use of any chemical processing. Within this work, we demonstrate that thermal annealing of sapphire into its ($\sqrt{31}$$\times$$\sqrt{31}$)$R$$\pm$9{\deg} reconstruction is a valid alternative preparation technique for sapphire substrates. TiN films grown via
plasma-assisted molecular beam epitaxy upon these substrates exhibit greater crystallinity than those grown on chemically cleaned sapphire substrates. Superconducting resonators fabricated from these films exhibit similar performance, with many possessing internal quality factors at single
photon levels greater than 10$^6$ for both substrate preparation methods.
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All authors Thomas J. Smart, Marc Neis, Janine Lorenz, Marcello P. Guardascione, Roudy Hanna, Michael Schleenvoigt, Yuan Gao, Joscha Domnick, Benjamin Bennemann, Abdur Rehman Jalil, Jin Hee Bae, Harsh Bhardwaj, F. Stefan Tautz, Felix Lüpke, Detlev Grützmacher, Rami Barends, Pavel A. Bushev, Peter Schüffelgen
Quantum Physics
Symmetry Alone Is Not an Ansatz: Task-Aligned Interactions in Equivariant Quantum Circuits
Markus Baumann, Claudia Linnhoff-Popien and Jonas Stein
The success of variational
quantum learning models crucially depends on choosing parametrizations that reflect the structure of the problem at hand.
Symmetries provide one of the clearest such structures: whenever transformations of the input leave the desired outcome unchanged, this invariance should be built into the model rather than discovered during training. However, imposing a
symmetry does not by itself determine a useful ansatz. Even within the
symmetry-preserving space, one must decide where the trainable degrees of freedom should be placed. In this work, we study this remaining design freedom in equivariant variational
quantum circuits. Building on
symmetry-based parameter sharing, we disentangle two architectural choices: how much
symmetry should be enforced, and which
symmetry-respecting interactions should be trainable. Using Tic-Tac-Toe as a fully enumerable and structurally transparent test case, we find that suitable subgroups preserve most of the generalization benefit. By contrast, the dominant gains arise from gates acting directly on decisive task motifs. Thus,
symmetry defines the admissible design space, while effective ansätze require an additional task-informed choice of trainable interactions.
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High Energy Physics (Theory)
Macroscopic Black-Hole Remnants in a Nonlocal Field Theory: Towards Hawking Radiation in SFT
Feng-Yin Cheng, Pei-Ming Ho and Wei-Hsiang Shao
We demonstrate that, for a large black hole of radius $a$, Hawking radiation terminates around the scrambling time $u_{\text{scr}} \equiv 2a \log(a/\ell)$ due to the nonlocal, exponential suppression of trans-Planckian interactions inherent in string field theory (SFT). Modifying a massless scalar field's interaction with a dynamical black hole background via the smearing operator $e^{\ell^2\Box}$ (where $\ell$ denotes the string length scale), we calculate the time-dependent number expectation value $\langle \hat{N}(u) \rangle$ of outgoing Hawking particles at retarded time $u$. While the standard Planck spectrum at the Hawking temperature is reproduced at early times ($u \ll u_{\text{scr}}$), the particle number approaches zero shortly after the scrambling time. This early shutoff reflects the property that the collapsing shell becomes effectively invisible to trans-Planckian modes, offering an alternative resolution to the black hole information paradox via a macroscopic remnant.
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Quantum Physics
Entanglement structure of the dynamical phases in the sub-Ohmic spin-boson model
Cunxi Gong, Zirui Sheng and Weitang Li
The sub-Ohmic
spin-
boson model exhibits three distinct dynamical regimes in its
spin population dynamics, classified as coherent, incoherent, and pseudo-coherent. Whether these regimes correspond to distinct
spin-bath
entanglement structures remains an open question. Here we address this using tree tensor network states with projector-splitting time
evolution (TTN-TDVP-PS), scanning a broad grid in the sub-Ohmic $(s, \alpha)$ plane. We find that the
spin entanglement entropy $S_\mathrm{spin}(t)$ reaches a stationary plateau on a timescale shorter than the polarization relaxation, enabling construction of a stationary
entropy landscape from the stationary value $S_\mathrm{stable}$. Within this scalar
entropy landscape, the
entropy ridge broadly follows the population-based phase boundary at small $s$, but does not reproduce the two-branch structure at large $s$. The ridge remains single-valued within the incoherent region rather than separately tracking both population-based transitions. The Bloch-sphere representation provides a
geometric interpretation of this behavior. The
entropy plateau corresponds to trajectories settling onto constant-radius shells, with the ridge marking the parameters of smallest stationary Bloch radius. Mode-resolved bath
entanglement shows that low-frequency modes dominate the environmental
entropy scale and that coherent dynamics enhance bath-mode correlations beyond direct
spin–mode correlations. These results establish the stationary
spin entanglement entropy as a physically informative observable that complements population-based classifications of dissipative
quantum dynamics.
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Strongly Correlated Electrons
Fractional excitations in Kitaev quasi-one-dimensional chain
Ritwika Majumder
The Kitaev honeycomb model has attracted significant interest due to its
quantum spin liquid ground state, fractionalized Majorana excitations, and topological properties. Motivated by these features, we introduce a quasi-one-dimensional Kitaev-like
spin chain derived from a truncated honeycomb geometry. The resulting Majorana band structure contains both dispersive and flat bands, with a gap closing at a critical anisotropy that separates trivial and
chiral topological phases. Under open boundary conditions, the topological regime hosts zero-energy edge modes protected by
chiral symmetry, placing the system in the BDI
symmetry class with a quantized winding number. In the excited spectrum, localized plaquette modes emerge near zero energy and can be tuned by introducing domains of negative plaquettes. The dynamical
spin correlation function reveals broad continua associated with fractionalized excitations, together with characteristic low-energy spectral weight from edge Majorana modes. These features distinguish the present system from conventional Heisenberg
spin chains and provide experimentally relevant fingerprints of
chiral topological order. Our model thus establishes a conceptual bridge between the two-dimensional Kitaev
spin liquid and Kitaev's one-dimensional
quantum wire.
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High Energy Astrophysical Phenomena
Evidence for candidate X-ray pulsations from the ultraluminous X-ray source NGC 7456 ULX-1
Yuanle Yao, Xiang-Dong Li and Xiao-Jie Xu
We report evidence for a candidate pulsational signal at $\sim0.22$~Hz from NGC7456 ULX-1, a previously identified ultraluminous X-ray source (ULX). The signal is identified in the 2023 XMM-Newton observation using independent timing techniques including accelerated searches, $Z^2_n$ statistics, and an orbital-demodulation analysis designed to restore phase coherence in the presence of binary motion. The candidate pulsation frequency drift within the observation suggests rapid
spin evolution driven by
accretion torque. We further estimate the surface dipole
magnetic field strength to be $B\sim 10^{12}-10^{14}$ G. These results provide evidence that NGC7456 ULX-1 may host an accreting
neutron star, although confirmation with independent
datasets or additional observations is required.
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Quantum Physics
Quantum Batteries as Work Sources for Phase-Locked Parametric Amplification
Borhan Ahmadi
Quantum batteries have been proposed as locally precharged work sources for superconducting
quantum technologies, suggesting a route to reduce continuously supplied microwave drives. Here we ask whether the pump tone of a
quantum-limited parametric amplifier can be replaced, or strongly duty-cycled, by a finite bosonic
quantum battery. Quantizing the pump of a nondegenerate parametric amplifier exposes a resource distinction hidden in the classical description: stored pump energy can generate signal-idler
photons, but pump phase coherence is required to generate a phase-locked amplifier field. In a closed trilinear model, coherent and phase-randomized coherent pumps with the same
photon-number distribution produce comparable pair numbers, yet only the coherent pump produces anomalous two-mode coherence and an EPR-squeezed interference dip. Including leakage, we collect the emitted fields into cascaded temporal modes. At matched collector bandwidth, the coherent pump gives \(I_{\min}^{(f)}=0.553\), whereas the phase-randomized pump gives \(I_{\min}^{(f)}=1.94\) at nearly identical collected energy. Weak amplitude squeezing slightly improves the dip by reducing finite-pump number fluctuations while preserving the coherent displacement. Thus battery-powered parametric amplification requires phase-coherent stored energy, possibly assisted by number-noise reduction, rather than stored energy alone.
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Solar and Stellar Astrophysics
Intermittent turbulent fluctuations in solar coronal mass ejections
Apurva Bhagat, Sumit Tambe, Debesh Bhattacharjee et al. (+1 more)
Localised regions of high intensity fluctuations are known to be signatures of intermittency in fluid and
plasma turbulence. We investigate such turbulent spots using near-Earth in-situ spacecraft observations of a sample of 125
solar coronal mass ejections (CMEs). We present statistical results which suggest that the intensity of the strongest turbulent spot and the turbulent spot occurrence rate are reliable indicators of the onset of the leading part of the CME event. Our findings also suggest that turbulent spots can be sites of enhanced
proton heating. The findings of this study can enhance our understanding of intermittence in collisionless
plasma turbulence and can improve CME/sheath-driven space weather impact prediction models.
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All authors Apurva Bhagat, Sumit Tambe, Debesh Bhattacharjee, Prasad Subramanian
High Energy Physics (Phenomenology) · Cross-listed from stat.ML
Statistical Properties of Training & Generalization
Itay Lavie, Noam Levi and Yonatan Kahn
Deep learning has managed to evade numerous intuitions from classical statistics to achieve unprecedented performance on a number of real-world tasks. In this article, we investigate the key features and surprises of deep learning from a physics-informed perspective, taking care to point out and justify where possible the many choices inherent in constructing a deep learning model. In particular, we review the phenomenon of neural scaling laws and discuss their interplay with the constraints and inductive biases which may be present when applying machine learning to problems in physics.
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Plasma Physics
Dephasingless laser wakefield acceleration in a plasma waveguide
J.P. Palastro, K.G. Miller, C.D. Arrowsmith et al. (+10 more)
Laser wakefield accelerators (LWFAs) provide extremely large accelerating gradients for compact electron accelerators and
photon sources but are limited by dephasing, where trapped electrons outrun the accelerating phase of the wakefield. Flying-focus pulses can eliminate dephasing by driving a wake at the
vacuum speed of light, but these pulses involve tradeoffs such as varying spot size, long duration, or large
plasma volume. Here we show that a spatiotemporally structured
laser pulse propagating in a
plasma waveguide can drive a wakefield at the
vacuum speed of light while maintaining a constant spot size and ultrashort duration. The pulse is formed by superposing
plasma-waveguide modes with appropriately selected frequencies. Compared with flying-focus approaches, the waveguide substantially reduces the required
plasma volume. Scaling laws and quasi-3D particle-in-
cell simulations show that the single-stage energy gain increases linearly with the number of modes used to construct the pulse, enabling larger energy gains or shorter stages than standard LWFA.
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All authors J.P. Palastro, K.G. Miller, C.D. Arrowsmith, R. Almeida, M.R. Edwards, A.L. Elliott, A. Kiewel, A. Konzel, L.S. Mack, D. Ramsey, D. Singh, A.G.R. Thomas, J. Vieira
Strongly Correlated Electrons
All-In-All-Out Pyrochlore Iridates as Noncollinear Spin-Orbit Coupled Counterparts of Altermagnets
Yang Yang, Turan Birol, Rafael M. Fernandes et al. (+1 more)
Altermagnets are collinear magnetically ordered states that exhibit momentum-dependent
spin splitting in the absence of net magnetization and
spin-orbit coupling (SOC). Related
spin-splitting patterns, however, can also emerge in noncollinear
magnetic systems with large SOC. Here we show, via a microscopic model, that the all-in-all-out (AIAO) state in pyrochlore iridates constitutes a noncollinear counterpart of a $d$-wave altermagnet stabilized by strong SOC. Starting from a microscopic $j_{\mathrm{eff}} = 1/2$ tight-binding model on the pyrochlore
lattice, we demonstrate that electronic interactions favor the AIAO phase and analyze its
symmetry properties. We show that the AIAO order parameter transforms as an $A_{2g}^{-}$ octupolar
magnetic moment, breaking time-reversal
symmetry while preserving inversion and zero net magnetization. Using group-theory analysis and mean-field calculations, we demonstrate that this
symmetry enforces both a
spin-polarized momentum-dependent lifting of band degeneracies that is similar to that of a collinear $d$-wave cubic altermagnet, but also a band splitting at zero-momentum. We show that the latter feature is captured by a low-energy model similar to the Luttinger-Kohn model for cubic
semiconductors. Our results identify pyrochlore iridates as a platform for noncollinear counterparts of altermagnetism and provide a general
symmetry framework for
spin-split phenomena in
spin-orbit coupled materials.
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All authors Yang Yang, Turan Birol, Rafael M. Fernandes, Natalia B. Perkins
Soft Condensed Matter
Multi-particle gates on driven one-dimensional paths: probing deep traps
Harsh Jain, Shankar Ghosh and Archishman Raju
We study single-file transport of driven overdamped colloidal particles on a periodic path with deep potential wells. In the small trap limit (i.e., trap size smaller than particle size), the particle current transitions from zero to finite as the number of particles on the path exceeds a critical number $n_c$. Beyond this threshold, $n_c$ particles cluster behind the trap, demonstrating collective correlated motion. The remaining `extra' particles circulate, giving a finite current. We study this phenomenon numerically using overdamped Brownian dynamics simulations, and present an experimental realization of this behaviour for micron-scale colloidal particles driven in an optical
vortex. Using our experimental observations, we present results characterizing potential wells as deep as several hundred $k_BT$.
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Mathematical Physics · Cross-listed from math.SG
Fourier-Helgason transform as infinite geodesic time limit in geometric quantization
Ana Cristina Ferreira, Joachim Hilgert, José M. Mourão et al. (+1 more)
The
Fourier-Helgason (FH) transform for a noncompact symmetric space $G/K$ establishes the direct integral decomposition of the
unitary representation of $G$ on $L^2(G/K)$ into irreducible principal series representations. By applying techniques of
geometric quantization to the
symplectic manifold $T^*(G/K),$ Lisiecki in 1987 gave a
geometric interpretation of the FH transform in the case when $G$ is complex. He defined for general $G$ a ”horizontal” polarization on $T^*(G/K)$ and showed that, for complex $G$, the Blattner-Kostant-Sternberg (BKS) pairing between the Schrödinger vertical polarization
Hilbert space, $L^2(G/K)$, and the
Hilbert space of horizontally polarized functions coincides with the FH transform. However, in the same paper, Lisiecki showed that for noncomplex Lie groups the BKS pairing is nonequivalent to the FH transform and nonunitary in general. In the present paper, we resolve this discrepancy between the FH transform and
geometric quantization in the case when $G$ is not complex. First, we show that the horizontal polarization is the infinite-time limit of the push-forward of the vertical polarization with respect to the geodesic flow for a $G$-invariant Riemannian metric. Then we lift the geodesic flow to an intertwining
unitary parallel transport on the
quantum bundle that we call
quantum geodesic transform (QGT). Finally we show that the QGT has a well-defined limit, as the geodesic time goes to infinity, and that it is equal, up to the phase of the Harish-Chandra $c$-function and an irrelevant multiplicative constant, to the FH transform.
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All authors Ana Cristina Ferreira, Joachim Hilgert, José M. Mourão, João P. Nunes
General Relativity and Quantum Cosmology
Constitutive birefringence and critical curves in the rotating García–Díaz black hole
Ariel Guzmán, Mohsen Fathi and J.R. Villanueva
We study high-frequency electromagnetic propagation in the rotating García–Díaz solution of Einstein
gravity coupled to NLED. In this system, light is not governed only by the null cone of the spacetime metric, because the NLED field also behaves as an optical medium whose constitutive response determines the physical optical cones. Starting from the mixed electromagnetic potentials, we project the field $F$ and the excitation $P$ on a principal tetrad and obtain the aligned scalars $E$, $B$, $D$ and $H$. These scalars allow us to reconstruct the regular local constitutive branch connected with Maxwell theory through the map $(D,B)\mapsto(E,H)$. We then insert the resulting response
matrix into the Fresnel characteristic problem. At the perturbative order considered here, the Fresnel quartic factorizes into two quadratic branches, each defining an effective optical metric. Both optical metrics admit Carter-type separation of the Hamilton–Jacobi equation and possess their own radial and angular potentials, critical constants and unstable critical families. By projecting these families onto the celestial sphere of a finite-distance observer, we obtain two critical contours, $\Gamma_+$ and $\Gamma_-$, which coincide in the Maxwell limit and split when the nonlinear constitutive response is active. We quantify this birefringent splitting through the maximum angular separation, the relative diameter shift and the normalized birefringent width. Numerical scans over the nonlinear coupling,
spin and observer inclination show that the splitting is generated by the constitutive response, redistributed by rotation and stable under local projection changes within the perturbative domain. This provides a direct geometrical link between the local NLED response and a polarization-dependent critical structure on the observer screen.
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Quantum Gases
Arrival times of an atomic Bose-Einstein condensate
Pascal Naidon, Lucas Happ and Denis Boiron
The times of flight of an atomic Bose-Einstein condensate are theoretically investigated in the experimentally unexplored regime corresponding to detection close to the trap of the condensate. In this regime, there is no consensus on how to calculate the distribution of times of arrival onto the detector. For non-interacting particles, distinct theoretical predictions have been made in the past. This work analyses how these predictions are modified for an interacting Bose-Einstein condensate. For this purpose, a time-dependent Gross-Pitaevskii equation is solved analytically and numerically.
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Superconductivity
Spin transport in a normal meta-altermagnetic superconducting nanowire junction
Xing-Jian Yi, Yi-Xin Dai, Yue Mao et al. (+1 more)
Spin triplet
superconductors are considered a promising platform for dissipationless
spin transport, where
spin currents are carried by
spin triplet Cooper pairs. In this paper, we propose that the
spin triplet superconductivity and
spin supercurrent can be engineered in an altermagnetic superconducting nanowire, where a one-dimensional nanowire is placed on the surface of an s-wave
superconductor and in proximity to the altermagnet. Using the nonequilibrium Green's function method, we demonstrate a nonzero equal
spin Andreev reflection coefficient at the normal metal-altermagnetic superconducting nanowire interface, thereby verifying the injection of
spin triplet Cooper pairs. Furthermore, we systematically investigate the
spin transport properties in this hybrid system under a
spin bias. Our results demonstrate that these properties can be effectively tuned by the chemical potential and
spin bias orientation. Our proposal provides a pathway toward realizing dissipationless
spin transport.
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All authors Xing-Jian Yi, Yi-Xin Dai, Yue Mao, Qing-Feng Sun
Quantum Physics
Proposal of quantum arrival-time measurement with a Bose-Einstein condensate
Pascal Naidon, Lucas Happ and Denis Boiron
This work shows how a Bose-Einstein condensate of ultracold atoms could be used to address a long-standing question in
quantum theory: how much time does it take for a particle to reach a detector? To this end, we propose a realistic experimental setup, whose key idea is not to measure arrival times directly, but the arrival flux on the detector as a function of its position. This novel approach not only solves practical issues with having a detector close to the system, but also results in signals that allow to unambiguously distinguish different theoretical predictions. This proposal raises prospects for resolving the decades-old debate on this fundamental issue.
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Mathematical Physics · Cross-listed from math.AG
Symplectic duality for the constant term of the geometric Eisenstein series
Igor Chaban
We study the
cohomology of a quasimap space that categorifies the constant term of the
geometric Eisenstein series for the mirabolic
parabolic subgroup of $GL$ over the function field $\mathbb{F}_q(C)$ of a smooth projective curve $C$. This
cohomology carries a natural action of an
algebra of correspondences whose commutative subalgebra is the ring of regular functions on the Coulomb branch, which here is the $A_{n}$-surface singularity. A choice of rank-one local system on $C$ induces an action of the étale fundamental group on the Coulomb branch; the scheme-theoretic fixed locus carries a natural vector bundle. Our main result identifies the
cohomology of the quasimap space with the local
cohomology of this vector bundle, for a generic range of parameters.
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Materials Science
Exciton Transport in Disordered Perovskite Nanocrystal Solids
Simon Solari, Enrique Arévalo Rodríguez, Antonella Cutrupi et al. (+6 more)
Solution-processed thin films of colloidal lead halide perovskite (LHP) nanocrystals (NCs) show great potential for the implementation into optoelectronic devices such as light-emitting diodes (LEDs),
lasers, and
solar cells. However, these hybrid LHP NC solids exhibit non-negligible size and shape polydispersity, which introduces both structural and energetic disorder. Here, we resolve the
exciton dynamics in space, time, and energy to elucidate the impact of different forms of disorder (structural and energetic) on
exciton transport. We show that the disorder depends sensitively on the length of the alkylamine ligand used in the synthesis. While shorter alkyl chain lengths lead to high polydispersity, longer alkyl chains lead to more monodispersed and smaller particles where
quantum confinement becomes more pronounced and, consequently, lead to increased energetic disorder. Strikingly, we find that
exciton transport is less efficient in NC solids with long alkyl chain ligands, despite having a significantly more monodisperse ensemble. This demonstrates that energetic disorder, rather than structural disorder, is the dominant factor for predicting
exciton transport within these materials. These findings reveal the critical role of ligand engineering in designing high-performance optoelectronic devices based on hybrid LHP NCs, providing new insights into energy transport dynamics in disordered systems and highlighting the versatility of these materials for advanced photonic and optoelectronic applications.
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All authors Simon Solari, Enrique Arévalo Rodríguez, Antonella Cutrupi, Amalia Coro, Marc Meléndez, Alicia De Andrés, Almudena Torres-Pardo, Beatriz H. Juárez, Ferry Prins
Quantum Physics
Interpreting Liouvillian Eigenmodes: Quantized Orbits in Dissipative Systems
Ashlin V Thomas, Felix Fritzsch, Masudul Haque et al. (+1 more)
In closed
quantum dynamics, energy eigenstates represent physical excitations which, for systems with a classical limit, localize on quantized orbits in phase space. Such a picture is lacking in open systems: Liouvillians have distinct right and left eigenstates that decay with time and are difficult to interpret. We recover a physical correspondence by introducing a gauge-invariant quasiprobability measure combining right and left eigenstates that interprets a Liouvillian mode as a set of coherences, allowing one to visualize the modes as quasiprobability distributions in a “doubled” phase space. Using this measure we show that, remarkably, a damped oscillator retains its quantized “orbits” for a large class of linear and nonlinear loss, with measurable signatures. A thermal bath broadens these orbits, similar to energy levels, leading to a characteristic multistage relaxation. This provides an experimentally accessible open-system analog of the eigenstate-orbit correspondence underlying semiclassical quantization. For quadratic systems, our results yield dissipative analogs of invariant
tori - a central concept in
Hamiltonian systems.
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All authors Ashlin V Thomas, Felix Fritzsch, Masudul Haque, Shovan Dutta
Lattice Field Theory
Confining Flux Tube in the Trace Deformed (2+1) Dimensional SU(2) Gauge Theory
Claudio Bonati, Michele Caselle, Alessio Negro et al. (+2 more)
We study the confining flux tube in the reconfined phase of trace deformed SU(2) Yang-Mills theory in (2+1) dimensions. Using
lattice simulations above the standard deconfinement temperature, we analyze Polyakov-loop correlators and extract the ground state energy of the effective string. We show that the usual Nambu-Goto effective string description, including its standard higher-order corrections, fails to reproduce the data as the trace deformation is increased. Remarkably, deep in the reconfined regime the results are instead accurately described by the Polchinski-Yang rigid-string solution, corresponding to an effective string dominated by an extrinsic-
curvature term. We further investigate the transverse profile of the chromo-electric flux tube and find significant deviations from the standard Yang-Mills behavior, including a substantial modification of the intrinsic width. Finally, we present an exploratory study of the phase diagram, finding evidence for a transition from a continuous to a first order reconfinement line as the deformation parameter increases. These results suggest that the reconfined phase realizes a qualitatively different effective-string regime from ordinary confinement.
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All authors Claudio Bonati, Michele Caselle, Alessio Negro, Dario Panfalone, Lorenzo Verzichelli
General Relativity and Quantum Cosmology
An explicit and differentiable Wilson-Daubechies-Meyer transform for gravitational-wave data analysis
Avi Vajpeyi, Giorgio Mentasti, Quentin Baghi et al. (+2 more)
The Wilson-Daubechies-Meyer (WDM) time-frequency transform has been widely used in gravitational-wave astronomy, yet a self-contained, mathematically explicit reference for practitioners remains lacking. This is especially true for those wishing to adopt the transform in modern Python and JAX inference workflows. We present wdm_transform, an open-source Python package implementing the WDM wavelet-packet time-frequency transform, and document its mathematical foundations, statistical properties, and practical implementation for gravitational-wave data analysis. The package supplies NumPy and JAX backends, both transforms (forward and inverse) validated to floating-point precision, with the JAX backend enabling GPU-accelerated transforms of million-point data streams in tens of milliseconds. As a worked example, we verify that the WDM-domain likelihood reproduces frequency-domain posteriors for a resolved LISA
galactic binary under a shared stationary noise model, confirming numerical equivalence of the two representations in that controlled setting. This work paves the way for systematic optimisation of WDM tilings, a particularly promising direction for the non-stationary noise,
stochastic backgrounds, and data gaps anticipated in future detectors, and for direct comparisons with alternative time-frequency representations needed to meet the challenges of future gravitational-wave data analysis.
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All authors Avi Vajpeyi, Giorgio Mentasti, Quentin Baghi, Ollie Burke, Lorenzo Speri
High Energy Physics (Phenomenology)
Three-particle di-light-cone distribution amplitudes of the $B$-meson in heavy-quark effective theory
Riccardo Bartocci, Philipp Böer, Thorsten Feldmann et al. (+3 more)
We present a systematic study of the three-particle di-light-cone distribution amplitudes (DLCDAs) of the $B$-
meson. They are defined through $B$-
meson–to–
vacuum matrix elements of trilocal HQET operators, in which the light antiquark and the
gluon field-strength tensor are located on two back-to-back light rays. In this sense, the DLCDAs generalise the conventional $B$-
meson light-cone distribution amplitudes to configurations where soft fields couple to collinear degrees of freedom in two distinct directions. As such, they parametrise the non-perturbative dynamics associated with non-factorisable soft-
gluon contributions in rare and non-leptonic exclusive $B$-
meson decays. We derive the complete Lorentz decomposition of the
matrix elements of generic trilocal operators, identify eight independent DLCDAs, and organise them in a basis of definite twist. Using local operator identities and equations-of-motion constraints, we obtain tree-level relations for their normalisation integrals and first moments in terms of a minimal set of hadronic parameters. These relations allow us to construct simple momentum-space models for all independent DLCDAs. For the leading-twist distribution, we further incorporate the perturbative radiative tail at order $\alpha_s$ and discuss its impact on the resulting parametrisation.
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All authors Riccardo Bartocci, Philipp Böer, Thorsten Feldmann, Max Ferré, Nico Gubernari, Daniel Vladimirov
Astrophysics of Galaxies
UCLCHEM 4.0: An open source gas-grain astrochemistry simulation framework
Gijs Vermariën, Serena Viti, Tobias M. Dijkhuis et al. (+4 more)
Astrochemical modelling is a key tool for interpreting the formation and destruction of molecules in the interstellar medium, complementing the increasingly detailed observations enabled by modern day observational facilities. UCLCHEM is a comprehensive gas-grain astrochemical modelling framework that can compute the chemical
evolution inside a parcel of gas and
dust under a specified, time-dependent physical description. This allows both the post-processing of hydrodynamical simulations and the usage of physical parametrizations, ranging in context from extra-
galactic to protoplanetary disk scales. The framework consists of a core routine that solves gas-grain chemical reaction networks as a function of time, self-consistently coupled to either a user-defined or parametrized physical
evolution of density, temperature and other physical input parameters. The chemistry is solved with a rate-equation formalism, and includes a three phase description, namely gas phase, ice surface and bulk ice. This includes transport between the gas and ice phases via freeze-out, thermal and non-thermal desorption mechanisms, as well as a geometrical treatment of the growth and shrinkage of the surface and bulk chemistry. The framework includes parametrizations for astrochemical modelling of cloud collapses, protostellar cores and shocks as well as the ability to provide user-defined inputs. This release of the framework focuses on many quality-of-life-improvements, including an object-oriented Python interface, an upgrade from two phase to three phases and expanded support for post-processing of hydrodynamical simulations and user-defined parametrizations. This manuscript provides an overview of the physics and chemistry included in UCLCHEM, as well as the inner workings of the solver routine and the programming interface.
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All authors Gijs Vermariën, Serena Viti, Tobias M. Dijkhuis, Le Ngoc Tram, Marcus Keil, Katarzyna M. Dutkowska, Felix D. Priestley
Quantum Physics
Vine Codes: Low-Overhead Quantum LDPC Codes on a Planar Square Grid
Georgia M. Nixon, Campbell K. McLauchlan and Charles C. L. van Rest
The surface code is a promising route towards large-scale
quantum computing, requiring only nearest-neighbour gates amenable to superconducting hardware. However, surface codes incur large
qubit overheads. Novel
quantum low-density parity check (qLDPC) codes promise to reduce overheads but require long-range connections that are difficult to achieve on superconducting platforms. Here, we introduce "Vine Codes" - qLDPC codes that are implementable on a planar square grid through nearest-neighbour, two-
qubit gates native to superconducting platforms (iSWAP and CZ). Our approach generalises "Directional Codes" recently introduced by Gehér et. al. (2025) which are constrained to a
torus. In contrast, vine codes have open boundary conditions constructed with the aid of routing
qubits. We perform extensive numeric searches and find promising candidate vine codes, e.g. [[121,4,6]], [[221,6,7]], and [[234,9,6]] codes. We verify the
circuit distances and show that data and measure
qubits required can be reduced by up to ~28% relative to the surface code at a
circuit distance of 7. Even including routing
qubits, vine codes require fewer total
qubits than the surface code (e.g. ~18% reduction at
circuit distance 10) and benefits are expected to increase at higher distances. We perform
circuit-level noise simulations to demonstrate that under a realistic noise model and at a near-term noise rate of $10^{-3}$, vine codes can perform better than the surface code while using fewer
qubits. We give an exhaustive list of all unique vine codes up to stabiliser-weight 9. We additionally introduce "Flip-Vine Codes" which possess single-
qubit transversal Clifford gates useful for fault-tolerant logic and magic state cultivation. We furthermore construct examples of generalised open boundaries for vine codes that go beyond the familiar X/Z boundaries of the surface and tile codes.
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Materials Science
Anomalous magneto-optical response at $\mathrm{RuO_2 / WSe_2}$ van der Waals interface
Muhammad Hassan Shaikh, Abhijith Puthiya Veettil, Collin Maurtua et al. (+9 more)
Ruthenium dioxide ($\mathrm{RuO_2}$) has been proposed as an altermagnetic candidate, although its
magnetic ground state remains controversial. Here, we probe weak interfacial
magnetic states at the surface of (001)-oriented $\mathrm{RuO_2}$ films using the
magnetic proximity effect (MPE) in a van der Waals
heterostructure consisting of monolayer tungsten diselenide ($\mathrm{WSe_2}$) atop $\mathrm{RuO_2}$. Temperature-dependent magneto-optical spectroscopy reveals an anomalous excitonic energy shift and a deviation from conventional Varshni behavior below 55 K that are absent in an encapsulated $\mathrm{WSe_2}$ control sample. The anomalous shift reverses sign upon field cooling with opposite
magnetic field polarity, indicating a
magnetic origin. Polarization-resolved measurements further show a nearly field-independent and fluctuating valley splitting in $\mathrm{WSe_2 / RuO_2}$ in strong contrast to the conventional linear Zeeman splitting observed in the control bare $\mathrm{WSe_2}$ sample. These results suggest that the valley states are governed predominantly by interfacial exchange fields associated with weak surface
magnetic states in $\mathrm{RuO_2}$, which do not produce a conventional linear Zeeman response within the applied
magnetic field range. Importantly, this approach enables direct optical probing of emergent surface magnetism without introducing an additional
ferromagnetic layer, positioning MPE-based optical probing as a tool for investigating weak surface magnetism and offering new possibilities for studying
magnetic materials with controversial
magnetic states.
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All authors Muhammad Hassan Shaikh, Abhijith Puthiya Veettil, Collin Maurtua, Dai Q. Ho, Subhash Bhatt, David T. Plouff, Malitha Gulawita, Kenji Watanabe, Takashi Taniguchi, John Q. Xiao, Anderson Janotti, Chitraleema Chakraborty
Soft Condensed Matter
Activity driven buckling and pattern formation in shells of oriented solids
Niels de Graaf Sousa, Varun Venkatesh and Amin Doostmohammadi
We investigate shells of active oriented solid, materials in which orientationally ordered active particles are embedded in a deformable elastic surface. Focusing on cylindrical geometries, we show that active stresses drive a new class of buckling instabilities and nonlinear patterns absent in passive shells. Linear stability analysis reveals that the unstable buckling mode is selected by the nematic orientation and activity sign, leading to axial, circumferential, and helical deformations. Remarkably, circumferential modes become unstable at arbitrarily small activity due to the absence of stretching costs. The results of the linear stability analysis are corroborated by full nonlinear simulations, which further uncover steady diamond shaped patterns and persistent dynamical states including oscillations, traveling domain walls, and propagating waves. Our results establish fundamental buckling modes and emergent patterns in shells of active oriented solid materials, with potential relevance to active biological tissues and engineered responsive materials.
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