Quantum Physics
Continuous Narrow-Linewidth Superradiance in Waveguide QED
Anna Bychek, Martin Fasser, Ivan Vybornyi et al. (+4 more)
Superradiant
lasers promise continuous, narrow-linewidth coherent emission at the bare atomic transition frequency, enabling frequency references of exceptional precision. Recent experiments have advanced the field, but achieving truly continuous operation remains technically challenging. Here we propose an alternative route to an active optical frequency reference with fewer emitters using all-to-all dipole-dipole interactions mediated by a nanophotonic waveguide. We show that selectively pumping only a sub-ensemble of emitters, rather than the full ensemble, substantially improves emission characteristics. The collective interactions with unpumped emitters provide narrowband frequency selection and establish an effective feedback mechanism analogous to the role of a macroscopic cavity. We find directional superradiant emission with strongly phase-synchronized emitter correlations and a narrow output spectrum close to the bare emitter resonance. Our results demonstrate a strong metrological gain from selective partial pumping of
quantum emitters with the second-order intensity correlation $g^{(2)}(0)\simeq 1$, indicating reduced equal-time intensity fluctuations, and open a route to waveguide-based optical frequency references using small clock-atom ensembles for chip-scale precision metrology.
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All authors Anna Bychek, Martin Fasser, Ivan Vybornyi, Klemens Hammerer, Susanne F. Yelin, Helmut Ritsch, Raphael Holzinger
Instrumentation and Methods for Astrophysics
LUnar-based Survey for Time-domain Exploration and Research network (LUSTER-net)
T. S. Boyajian, R. A. Street, B. Fleming et al. (+7 more)
LUSTER-net is a lunar-surface UVOIR observatory network mission concept for time-domain astrophysics. The concept envisions a scalable array of approximately 6-12 commonly designed
telescope nodes, with apertures in the $\sim0.5-1$ m class, distributed across the lunar surface to provide long-duration monitoring, rapid follow-up, and coordinated imaging and spectroscopy of transient and variable sources. By combining continuous observing windows from the lunar surface with adaptive network scheduling, LUSTER-net would provide persistent UVOIR characterization of discoveries from facilities such as Rubin, Roman, ULTRASAT, UVEX, and multi-messenger observatories. The science enabled includes
exoplanet atmosphere studies, microlensing parallax,
Solar System object characterization, fast transients, electromagnetic counterparts to multi-messenger events, and broader UVOIR variability studies. This white paper outlines the science motivation, notional architecture, implementation trades, and role of LUSTER-net as a step toward future lunar astrophysics facilities.
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All authors T. S. Boyajian, R. A. Street, B. Fleming, F. Marchis, J. Morse, P. Gandhi, J. Turner, G. Rau, A. Tanner, A. Sohani
Mesoscale and Nanoscale Physics
Half state at $\nu_{tot}$ = -1/2 and its transition in Decoupled Twisted Double Bilayer Graphene
Ning Ma, Kenji Watanabe, Takashi Taniguchi et al. (+1 more)
The origin of the fractional state at $\nu$ = 1/2 observed in double-layer
quantum Hall systems has been under debate for decades. Because of the variation of
bilayer charge distribution and interlayer tunneling strength, the half-filling state can be attributed to a two-component(2C) or a one-component(1C) origin, which corresponds to Halperin state and Pffafian state, respectively. Here we report the magnetotransport measurement in decoupled twisted double
bilayer graphene(TDBG), which has been proved to be a promising platform for double
quantum Hall system. Fractional
quantum hall states in both odd and even denominator fillings are observed. We also found that the half-filling state occurs at zero displacement field at $\nu_{tot}$ = -1/2, which is theoretically consistent with two-component Halperin-Laughlin ({\Psi}331) state. Moreover, we report the transition from two-component state at zero D field to one-component non-Abelian state by tunning displacement field. Our observation of the half filling state and its transition from 2C to 1C state provides the tunability of decoupled twisted double
bilayer graphene and shed light on the understanding of the ground states at half-filling factor in the double
quantum Hall system.
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All authors Ning Ma, Kenji Watanabe, Takashi Taniguchi, Mitali Banerjee
Astrophysics of Galaxies
High $^{12}$C/$^{13}$C isotopic ratios toward G+0.693-0.027: evidence for gas inflow to the Central Molecular Zone
L. Colzi, O. Sipilä, I. Jiménez-Serra et al. (+4 more)
Isotopic ratios are key tracers of
Galactic chemical
evolution because different isotopes are synthesized through distinct
stellar nucleosynthesis processes. While the $^{12}$C/$^{13}$C ratio increases with galactocentric distance across the
Galactic disc, measurements in the Central Molecular Zone (CMZ) have historically yielded low values ($\sim$3-30), often affected by high optical depths. We aim to determine the initial $^{12}$C/$^{13}$C ratio of the parent material of the CMZ molecular cloud G+0.693$-$0.027 using optically thin molecular tracers and correcting for isotopic fractionation. We analyzed an ultra-high-sensitivity spectral survey obtained with the IRAM 30m and Yebes 40m
telescopes, detecting single and double $^{13}$C isotopologues of HC$_3$N and HC$_5$N. Column densities and isotopic ratios were derived and compared with astrochemical models including $^{13}$C- and $^{15}$N-isotopologues to quantify isotopic fractionation. We derive $^{12}$C/$^{13}$C ratios of $36.7\pm1.0$ for HC$_3$N (using double $^{13}$C isotopologues) and $38.8\pm1.5$ for HC$_5$N, significantly higher than previous CMZ estimates based on simpler molecules. The models indicate low to intermediate isotopic fractionation at early times ($<3\times10^4$ yr), implying an initial $^{12}$C/$^{13}$C ratio of $\sim$48 for the gas from which present-day CMZ molecular clouds formed. The inferred range (37-48) is consistent with values observed at Galactocentric distances of 3-5 kpc, supporting a scenario in which the CMZ is replenished by gas inflows from the
Galactic disc driven by the
Galactic bar, with a possible contribution from less chemically processed material accreted from external systems such as
dwarf galaxies.
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All authors L. Colzi, O. Sipilä, I. Jiménez-Serra, V. M. Rivilla, M. Sanz-Novo, S. Martín, S. Zeng
Quantum Physics
Quantum state localization in dipole-dipole interacting disordered networks
Pritam Chattopadhyay, Saikat Sur, Avijit Misra et al. (+3 more)
We study the localization of excitations in positionally disordered
spin or atom networks coupled via the realistic resonant dipole-dipole interaction (RDDI), which does not conform to a simple power law, as the spatial dependence and dissipative character distinguish it from conventional short or long-range models. Despite its partially long-ranged and radiative nature, positional disorder in the RDDI coupling leads to strong spatial localization of excitations. The interplay between coherent and dissipative couplings gives rise to nontrivial interference effects that stabilize localized modes even in open geometries. Our results uncover a
photon wavelength-induced transition from extended to localized excitation dynamics, establishing RDDI networks as a unique setting to explore the emergence of localization in realistic
quantum optical systems. Our analysis of the localized modes induced by RDDI has potential applications in coherent photovoltaics, excitonic
circuits,
quantum memory, and
quantum sensors.
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All authors Pritam Chattopadhyay, Saikat Sur, Avijit Misra, David Petrosyan, Arti Garg, Gershon Kurizki
High Energy Physics (Phenomenology)
Predictions for $b$-baryon lifetimes at NNLO-QCD
Alexander Lenz, Maria Laura Piscopo and Aleksey V. Rusov
Motivated by recent and forthcoming experimental progress, we provide updated predictions for the total decay rates of $b$-
baryons, their lifetime ratios and their lifetimes normalised to that of the $B^0_d$
meson within the framework of the heavy
quark expansion (HQE). We include, for the first time, next-to-next-to-leading-order QCD corrections to the free $b$-
quark decay, which significantly reduce the theoretical uncertainties in the total decay rates. In addition, we also include, for the first time, the complete next-to-leading-order QCD corrections to the dimension-five contributions. While these corrections have only a minor effect on the total decay rates, they induce a sizeable shift in the lifetime ratios, improving the agreement between HQE predictions and experimental data. Overall, we find excellent agreement between the HQE predictions and current experimental measurements for both total decay rates and lifetime ratios within the quoted uncertainties.
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Cosmology and Nongalactic Astrophysics
One with HI: Modelling HI Intensity Mapping one-point statistics including systematics
Bernhard Vos-Gines and Cora Uhlemann
Neutral hydrogen (HI) traces the dark matter distribution of the Universe. Upcoming surveys such as the Square Kilometre Array Observatory (SKAO) will trace neutral hydrogen up to z < 6 using several detection techniques including Intensity Mapping, which offers a unique window to explore the post-reionization Universe. Beyond two-point statistics promise to extract additional non-Gaussian information but require an accurate modelling of observational systematics such as foregrounds and the
telescope beam. This work develops a theoretical model for the HI one-point probability density function (PDF) in spherical
cells based on large-deviation statistics and spherical collapse for dark matter along with a nonlinear tracer bias and stochasticity parameterisation. It incorporates foreground removal and
telescope beam effects that are validated against high-resolution simulations. We show that, despite these observational systematics, the HI PDF is able to capture additional non-Gaussian information from HI intensity maps compared to the power spectrum and can thus tighten constraints on cosmological parameters, breaking the degeneracy between the linear bias and the clustering amplitude.
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Quantum Physics
Differentially private quantum sensor networks
Daniel J. Spencer, Kaiyan Shi, Emil T. Khabiboulline et al. (+2 more)
Quantum sensing is a promising technology capable of demonstrating clear advantage over comparable classical techniques for precise measurement. One application of
quantum sensing is in function estimation, which can be done using a network of entangled
quantum sensors, allowing for measurements with greater optimal sensitivity than unentangled sensing protocols. In cases where
quantum sensor networks will be used to measure data that should remain private (e.g., biomedical data), it is imperative that these protocols include a
privacy mechanism to hide sensitive information. In this work, we show that entangled sensor networks are vulnerable to certain
privacy-violating attacks. To mitigate these attacks, we introduce secure sensing protocols endowed with differential
privacy. We reconcile differential
privacy with retaining Heisenberg-limited scaling, and introduce several protocols achieving varying balances between the two. We show that our main protocol, an $n$-node network sensing protocol that injects noise directly into the sensing
Hamiltonian, exhibits a tradeoff between the desirable $O(1/n^2)$ Heisenberg scaling of the mean-squared error of the function estimate and the level of
privacy attainable. Under assumptions on the network (a common source of randomness and a constant fraction of honest parties), we show that this protocol is locally implementable and achieves $(O(1), \delta)$-differential
privacy for arbitrarily small $\delta$ while retaining Heisenberg scaling of the mean-squared error. We prove that our protocols are resilient to attacks by broad classes of classical and
quantum adversaries, and find advantages in the
privacy-utility tradeoff when using
quantum techniques.
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All authors Daniel J. Spencer, Kaiyan Shi, Emil T. Khabiboulline, Gorjan Alagic, Alexey V. Gorshkov
Superconductivity
Multi-Knob Switchable Chiral Superconductivity Quartet in Rhombohedral Graphene
Zhenqi Hua, Shenyong Ye, Phatthanon Pattanakanvijit et al. (+17 more)
Chiral superconductors break orbital time-reversal
symmetry and may host topological quasiparticles with non-Abelian statistics. In rhombohedral
graphene, superconductivity develops from a
spin-valley-polarized quarter-metal (QM) parent state and features unique
magnetic hysteresis of resistance that indicates orbital time-reversal-
symmetry-breaking. Exploring and controlling the full
spin-valley
flavors of such superconductivity could enable novel superconducting and topological devices, but have remained unexplored. Here we report transport measurements on rhombohedral hexalayer
graphene (R6G), which reveal a new superconducting state (SCH) that is induced by an out-of-plane
magnetic field, in addition to
chiral superconductivity (CSC) similar to those observed in thinner layers. This SCH state emerges above 0.8 T, persists up to 1.6 T and can be switched on/off by
magnetic field $H_\perp$, carrier density $n$, and gate displacement field $D$.
Quantum oscillations and anomalous
Hall measurements show that SCH stems from a field-induced quarter-metal (QM$'$) parent phase, which carries orbital magnetization opposite to that of the zero-field QM. Across the full $(n, D, H_\perp)$ parameter space, superconductivity can be realized from all four
spin-valley isospin
flavors, establishing a switchable
chiral-
superconductor quartet in R6G. We interpret the parent-state switching as arising from competition between a Kane-Mele-like
spin-valley splitting and
magnetic-field coupling to
spin-valley-dependent
magnetic moments. Our work establishes rhombohedral
graphene as a multi-knob platform for different isospin-polarized superconductivities, which enables programmable superconducting networks with possible Majorana modes along domain walls.
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All authors Zhenqi Hua, Shenyong Ye, Phatthanon Pattanakanvijit, Gang Shi, Tonghang Han, Emily Aitken, Jixiang Yang, Junseok Seo, Haoyang Liu, Ran Hao, Kaitai Xiao, Jiaxing Guo, Vo Tien Phong, Kenji Watanabe, Takashi Taniguchi, Chunli Huang, Cyprian Lewandowski, Long Ju, Peng Xiong, Zhengguang Lu
Optics
High-Accuracy Semi-Analytical Method for Solving the Problem of Electromagnetic Wave Scattering by Arbitrary Ensembles of Parallel Circular Cylinders
V.V. Ternovski and M.I. Tribelsky
A method is proposed for solving the two-dimensional problem of electromagnetic wave scattering by a cluster of an arbitrary number of parallel, infinitely long, homogeneous, non-overlapping right circular cylinders. The cylinders may have arbitrary radii and complex permittivities, and their axes, while remaining parallel, may occupy arbitrary positions in the transverse plane. The solution is constructed using an analytical expansion of the electromagnetic field in cylindrical harmonics. Multiple scattering is taken into account by Graf's addition
theorem, which leads to a system of linear equations for the expansion coefficients. This system is solved numerically with condition number monitoring and, when necessary, extended-precision arithmetic, followed by a multistage verification of convergence. The method provides numerically verified solutions with controlled accuracy over a wide range of parameters, including densely packed subwavelength configurations. As an example, scattering of a normally incident, linearly polarized monochromatic plane wave by a subwavelength cluster of three identical aluminum nanocylinders (nanowires) is studied. The scattering, absorption, and extinction cross sections, as well as the scattering indicatrix, are computed and analyzed. Streamlines of the Poynting vector field are constructed, demonstrating redistribution of the energy flux between the cylinders of the cluster and the formation of localized regions of field enhancement near their surfaces.
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High Energy Physics (Phenomenology)
Interplay of CPT-Violating and CPT-Conserving Lorentz Invariance Violation at DUNE
Priyankush Deka, Arnab Sarker, Moon Moon Devi et al. (+1 more)
We present a study of Lorentz invariance violation (LIV) in
neutrino oscillations, with primary emphasis on the interplay between CPT-violating and CPT-conserving Standard Model Extension (SME) coefficients. We find that $a_{ee}$ and $a_{\tau\tau}$ dominate among the diagonal LIV coefficients, whereas $a_{e\mu}$ and $a_{e\tau}$ provide the most significant off-diagonal contributions. In contrast, the corresponding $c_{\alpha\beta}$ coefficients have comparatively sub-leading effects. Taking DUNE as a representative long-baseline experiment, we show that the sensitivity to CP violation is modified by LIV in a parameter-specific manner. We find correlations between off-diagonal LIV parameters, and non-trivial dependence on the new phases. In absence of LIV, DUNE is expected to establish CP violation at $5\sigma$ for a limited fraction of $\delta_{CP}$ values. We find that the presence of $a_{ee}$, $a_{\tau\tau}$, $a_{e\mu}$ and $a_{e\tau}$ weakens the CP discovery potential, reducing the achievable significance to below $3\sigma$ over a substantial fraction of $\delta_{\rm CP}$. The independent impact of $c_{\alpha\beta}$ terms also results in suppression, but in combination with $a_{\alpha\beta}$, they introduce degeneracies, complicating the extraction of $\delta_{CP}$. This generally results in a deterioration of CP violation sensitivities below $5\sigma$. These findings emphasize the importance of incorporating LIV effects in precision oscillation studies at upcoming long-baseline experiments.
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All authors Priyankush Deka, Arnab Sarker, Moon Moon Devi, Sushant K. Raut
Statistical Mechanics
Static vacancies as parametrized conformal defects in the critical $J_1$–$J_2$ transverse-field Ising chain
R. L. Silva, R. C. Silva, R. J. C. Lopes et al. (+1 more)
We revisit the problem of two static nonmagnetic vacancies in the transverse-field Ising chain with first- and second-neighbor couplings $J_1$ and $J_2$, now on the critical line, using density-
matrix renormalization-group (DMRG) calculations in open chains of up to $N=300$ sites. In contrast to the gapped regime studied previously, where the vacancy-vacancy interaction decays exponentially, along the entire
quantum critical line the interaction becomes algebraic, $|\Delta_b(r)|\sim r^{-\alpha}$, with $\alpha$ close to the universal Casimir value of unity and a weak but systematic dependence on the second-neighbor coupling, $\alpha_\infty \simeq 1.070 + 0.091\, J_2/J_1)$ across $J_2/J_1\in[0.1,1.0]$. The transmission ratio of the
spin correlator across a vacancy approaches a $J_2$-dependent plateau $T_\infty(J_2)$ that grows from $0.11$ to $0.33$ over the same range, and the Affleck-Ludwig boundary
entropy is small and approximately constant, $\log g_\infty \approx -0.073$, well above the Ising fixed-BC value $-\ln\sqrt{2}$ and close to the free-boundary value. The three observables vary smoothly and monotonically with $J_2$, consistent with a one-parameter family of partially transmissive conformal defects controlled by $J_2$. Throughout, the critical line is located using the bulk
spin-correlator exponent $\eta=1/4$, the order-parameter exponent of the Ising universality class, which provides a robust criterion in this open geometry.
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All authors R. L. Silva, R. C. Silva, R. J. C. Lopes, A. R. Pereira
Soft Condensed Matter
Sedimentation equilibrium and gravity dependent stiffness coefficients of colloidal hard-spheres
Luis G. MacDowell and Eva G. Noya
Spherical colloids with harsh repulsive forces have long been used as experimental analogs of the hard sphere model, with demonstrated good agreement with computer simulations for bulk and structural properties of the fluid, glass and
crystal phases. However, an enigmatic discrepancy remains for the
crystal-melt stiffness coefficient. Here we perform computer simulations of colloidal hard spheres under tunable buoyant mass and show that the long-standing discrepancy can be traced to a hitherto unrecognized
gravity dependent contribution of the stiffness coefficient. This effect is one practical realization of a more general result for the external field dependence of stiffness coefficients of arbitrary interfaces.
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Quantum Physics
Leveraging Metrologically Useful States in Quantum Reservoir Networks
Erik L. Connerty, Margarite LaBorde and Ethan N. Evans
Interest in using
quantum computers for the purpose of predicting chaotic partial differential equations (PDEs) has been growing with the advent of newer low-error
quantum computers and robust simulation tools. In this paper, we present a method that utilizes a
quantum reservoir network (QRN) to predict latent space representations of the high-dimensional chaotic 1-D Kuramoto-Sivashinksy (KS) system. This hybrid approach takes advantage of advancements in classical machine learning (ML) through the use of a classical autoencoder as well as techniques from
quantum metrology through the use of a
unitary that creates metrologically-useful states. Through rigorous simulation and analysis, we show that the proposed method outperforms alternative QRN implementations without this metrologically-useful state preparation, and also show better performance than classical echo-state networks when weight regularization is not used. Finally, we bring to light potential issues that can arise when using autoencoders within QRC pipelines.
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High Energy Physics (Theory)
Effective Lagrangian of a fermion field in a nontrivial topology under magnetic effects
Emerson B. S. Corrêa, Michelli S. R. Sarges, Airton H. G. Rodrigues et al. (+1 more)
We have investigated a fermionic system from the perspective of an effective
quantum field theory defined on a nontrivial
topology in the presence of an external
magnetic field. Using the proper-time representation, we obtained one-loop expressions for the corresponding effective Lagrangian, taking into account all Landau levels in the propagator. We also computed the significant boundary-induced contributions to the system's magnetization. To verify the reliability of our results, we examined the limit of zero temperature and infinite spatial extent, which correctly reproduces the celebrated Schwinger result.
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All authors Emerson B. S. Corrêa, Michelli S. R. Sarges, Airton H. G. Rodrigues, Carlos A. Bahia
High Energy Physics (Theory)
Holographic Tests of the $\mu$ Ensemble
Nikolay Bobev, Fridrik Freyr Gautason and Jesse van Muiden
We study in detail a recent proposal stating that M-theory observables arising from the quantisation of M2-branes are naturally computed in a fixed $A_3$ ensemble. In a
holographic setting this implies that in a semiclassical approximation 11d bulk observables in an asymptotically AdS$_4$ background are computed in a grand canonical ensemble of fixed chemical potential $\mu$ conjugate to the integer $N$ determining the rank of the gauge group in the dual CFT. We provide detailed precision tests of holography in the fixed $\mu$ ensemble by focusing on the two leading terms in the derivative expansion of the 11d theory. In addition, we study one-loop logarithmic corrections which we compute in detail. For asymptotically AdS$_4\times S^7/\mathbf{Z}_k$ 11d backgrounds our results are in agreement with supersymmetric localisation calculations in the dual ABJM SCFT. Moreover, we employ the logarithmic corrections in the $\mu$ ensemble to determine the measure of the integral Laplace transform and use this to compute dual SCFT supersymmetric partition functions, like the superconformal index and the squashed $S^3$ partition function, to all orders in the perturbative $1/N$ expansion in terms of Airy functions in harmony with results and
conjectures in the dual SCFT.
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Mesoscale and Nanoscale Physics
Correlated Insulating States in Twisted Double Bilayer Graphene Enhanced by Interfacial Effect on CrOCl
Ning Ma, Zekang Zhou, Chiara Cocchi et al. (+7 more)
Interaction between different two dimensional materials can give rise to many exotic physical phenomena which are rarely observed in intrinsic materials. Recently, several theoretical and experimental works have revealed that
magnetic proximity effect between pristine
graphene and
magnetic substrates can lead to the emergence of
quantum anomalous
Hall states and
quantum spin Hall states. However, interplay between correlated states in
graphene-based systems and
magnetic materials has seldom been studied. Here we perform the transport measurement at ultrahigh
magnetic field of twisted double
bilayer graphene (TDBG) on CrOCl (COC) substrate, which is an
antiferromagnetic material. Instead of a
magnetic-exchange effect on
graphene, we observe an enhanced correlated insulating state at half-filling factor of TDBG as a result of the charge-transfer process between TDBG and COC. The temperature and
magnetic field dependence of this enhanced state are further studied. Our results demonstrate the influence of charge-related effect at the interface, and shed a light on a new route for manipulating the correlated states in
graphene-based moiré systems using interfacial engineering.
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All authors Ning Ma, Zekang Zhou, Chiara Cocchi, Maurice Bal, Maarten van Delft, Kenji Watanabe, Takashi Taniguchi, Steffen Wiedmann, Jian-Hao Chen, Mitali Banerjee
Earth and Planetary Astrophysics
A parameterised approach to disequilibrium retrievals in the JWST era: Application to NIRCam observations of HD 189733b
Jake Taylor, Shang-Min Tsai, Vivien Parmentier et al. (+2 more)
Atmospheric
retrievals are a widely used technique for inferring the physical and chemical properties of exoplanetary atmospheres from observed spectra. A common simplifying assumption in such analyses is that the atmosphere is in thermochemical
equilibrium, which allows the use of precomputed chemical abundance grids as a function of pressure, temperature,
metallicity ([M/H]), and carbon-to-oxygen ratio (C/O). However,
exoplanet atmospheres often deviate from
equilibrium, particularly at lower temperatures or in the presence of strong vertical mixing. In this work, we investigate the impact of disequilibrium chemistry on
retrieval outcomes by generating synthetic James Webb Space
Telescope (JWST) observations of HD\,189733\,b with varying strengths of vertical mixing. We demonstrate that assuming thermochemical
equilibrium can lead to significant biases in the retrieved atmospheric parameters, including incorrect estimates of C/O and [M/H]. To address this, we incorporate transport-induced quenching of carbon and nitrogen-bearing species into the
retrieval framework by allowing the quench pressures to be free parameters. We show that this approach recovers the correct bulk atmospheric properties in most cases. Finally, we apply our disequilibrium
retrieval model to published JWST/NIRCam transmission observations of HD\,189733\,b and find tentative evidence for quenching. We also find tentative evidence for the photochemically active region of the atmosphere via a newly developed H$_2$S parameterisation, this is the first time this has been constrained in a hot Jupiter atmosphere.
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All authors Jake Taylor, Shang-Min Tsai, Vivien Parmentier, Chloe Fisher, Michael Line
Quantum Physics
Design and Benchmarking of a Quantum Photonic Chip
Gabriele De Angelis, Nicolò Leone, Alessandro Luongo et al. (+7 more)
We present the design and benchmarking of RP000, a
quantum photonic processor capable of encoding a
quantum system in the degrees of freedom of single
photons, based on standard CMOS-compatible manufacturing processes, and working at room temperature. We
benchmark it against machine learning tasks, evaluating three
quantum-classical architectures of increasing complexity. Our experimental results and simulations show that RP000 achieves higher accuracy than classical networks of comparable size in multiple use cases. Compared to a superconducting
quantum processor, RP000 exhibits superior noise tolerance. These findings demonstrate that RP000 can provide a scalable route toward efficient
quantum applications.
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All authors Gabriele De Angelis, Nicolò Leone, Alessandro Luongo, Alberto Montanaro, Matteo Sanna, Roberto Siagri, Vito Sorianello, Luigi Tallone, Fabrizio Tamburini, Marco Venere
High Energy Physics (Theory)
Abelian 2-Form Gauge Theory: Basic Canonical Brackets and Nilpotency Property of the Noether (Anti-)BRST Charges
R. P. Malik
Within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism, we invoke the beauty of the basic canonical (anti)commutators to prove the nilpotency property of the Noether (anti-)BRST charges for the D-dimensional BRST-quantized version of the free Abelian 2-form gauge theory which is endowed with a non-trivial Curci-Ferrari (CF) type restriction. In this proof, we use only the theoretical strength of the Gauss divergence
theorem. We demonstrate that, under the off-shell nilpotent (anti-)BRST
symmetry transformations, the Noether conserved (anti-)BRST charges are not invariant and they are also found to be not off-shell nilpotent (if we exploit the standard relationship between the continuous
symmetry transformations and their generators as the Noether conserved charges). However, these charges become (anti-)BRST invariant and nilpotent if we use (i) the appropriate equations of motion at suitable places, and (ii) the Gauss divergence
theorem. We derive the consistently modified versions of the Noether (anti-)BRST charges which are invariant under the off-shell nilpotent (anti-)BRST transformations. We prove the (anti-)BRST invariance of these modified versions of charges by using the basic canonical (anti)commutators, too. We discuss the physicality criteria w.r.t. (i) the conserved Noether (anti-)BRST charges, and (ii) the modified (anti-)BRST invariant versions of the Noether (anti-)BRST charges. We prove the superiority of the latter over the former (in view of the consistency with the Dirac quantization conditions for the gauge theories).
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Mathematical Physics · Cross-listed from cs.AI
A Physics-Informed Neural Network Framework for Elastodynamic Wave Propagation in Bimaterial Systems
Sonal Ankush Chibire, Jenn-Terng Gau and Bo Zhang
Physics-informed neural networks (PINNs) provide a promising framework for solving partial differential equations while
embedding the underlying physical laws directly into the learning process. This study presents a PINN-based framework for modeling transient elastodynamic wave propagation in bimaterial systems governed by the axisymmetric equations of linear elasticity. A steel-aluminum specimen representative of a Split Hopkinson Pressure Bar configuration is considered, and the governing elastodynamic equations, together with the corresponding initial, boundary, and interface conditions, are incorporated directly into the network through a physics-informed loss function. High-fidelity finite-element simulations performed using ANSYS Workbench Explicit Dynamics are used for validation and as supplementary data constraints during training. The proposed framework accurately predicts wave transmission and reflection across the bimaterial interface and reproduces axial and radial displacement histories, face-averaged responses, and the dominant stress and strain
evolution with close agreement to the finite-element solutions. The trained network further demonstrates the ability to predict wave responses at previously unseen time instants and for modified material properties without requiring additional finite-element simulations, providing a continuous surrogate model for elastodynamic analysis. Mesh-sensitivity studies confirm numerical robustness, while additional material combinations demonstrate the generality of the proposed methodology. The results show that integrating physics-informed neural networks with explicit finite-element analysis provides an accurate and computationally efficient framework for elastodynamic wave propagation in heterogeneous solids, offering an effective surrogate modeling approach for high-rate solid mechanics and impact engineering applications.
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Quantum Physics
Typical Entanglement of Superpositions
Damien Quinn, Joshuah T. Heath and Graham Kells
We investigate universal
entanglement properties inherent to superpositions of randomized states. We find that an $m$-fold superposition of typical states may be classified into two distinct
entanglement classes via the 2nd Rényi
entropy density $s_2$. The maximally entangled regime is defined by $s_2 \sim \ln (2)$, for which superposition adds no additional
entanglement. The sub-maximally entangled regime, $s_2<\ln 2$, instead constrains the reduced density
matrices of independent components to be orthogonal in the thermodynamic limit, which fixes the
entanglement of the superposition to a logarithmic enhancement $\Delta S(m)=\ln (m)$. As a consequence, an exponentially large number of superpositions is required to transition from the sub-maximally entangled class to maximal
entanglement. We explicitly calculate $s_2$ and the logarithmic enhancement, and demonstrate orthogonality for two canonical examples of the sub-maximally entangled regime (superpositions of pure Gaussian states and of random
matrix-product states). We also examine the
entanglement of superpositions of random stabilizer states, and discuss their relaxation to the Haar limit.
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Quantum Physics
Provable learning separation for predicting time-evolution of quantum many-body systems
Rahul Bandyopadhyay, Riccardo Molteni, Jens Eisert et al. (+2 more)
Given that
quantum computers are naturally suited to simulate the behavior of
quantum many-body systems, an immediate question arises: can one formulate physically motivated
quantum machine learning (QML) tasks that exhibit learning separations? We address this problem by studying the learnability of
quantum many-body dynamics from the perspective of probably approximately correct (PAC)-learning. Concretely, we devise a supervised learning problem where the training set consists of specifications of randomized stabilizer probe states,
evolution times sampled uniformly from a polynomially large time interval $[0,T]$, coupled with expectation values of certain observables evaluated on the resulting time-evolved state under an unknown
Hamiltonian. For this learning task, we provide an efficient
quantum procedure whose training phase learns the underlying
Hamiltonian from short-time training samples, and whose deployment phase combines
Hamiltonian simulation with the classical shadows protocol to perform inference on a newly given data point. By contrast, the existence of $O(\mathsf{poly}(n))$-time instances ensures classical hardness: by
embedding a $\mathsf{BQP}$-complete computation into the polynomially long time-dynamics of a low-intersection variant of the Feynman-Kitaev clock
Hamiltonian construction, we show that, for a certain family of input distributions, no randomized classical
polynomial-time
algorithm can fulfill our learning condition, unless $\mathsf{BQP}\subseteq\mathsf{P/poly}$. Furthermore, we show that the classically hard instance maintains
quantum learnability. We also give an interpretation of our results in learning-assisted certified
quantum simulation. Taken together, our results demonstrate a rigorous learning separation for a natural ML task based on
Hamiltonian evolution, while building connections between
quantum learning theory,
quantum simulation, and QML.
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All authors Rahul Bandyopadhyay, Riccardo Molteni, Jens Eisert, Vedran Dunjko, Sofiene Jerbi
Materials Science
Phonon-Mediated Thermal Transport in Nanocrystalline Silicon Using Machine-Learning Interatomic Potentials
Houssem Rezgui, Catalina Coll Benejam, Clivia M. Sotomayor Torres et al. (+1 more)
Understanding
phonon-mediated heat transport in structurally complex materials remains a central challenge for next-generation electronic and nanomechanical devices, where grain boundaries and interfacial disorder strongly limit thermal dissipation. Although classical interatomic potentials enable large-scale simulations, their limited transferability can lead to inaccuracies in vibrational properties and interfacial
phonon scattering. In this work, we develop a machine learning-based framework for modeling thermal transport in bulk and nanocrystalline silicon by combining Gaussian approximation potential and multi-atomic cluster expansion models with
lattice-dynamical calculations and molecular dynamics. Harmonic and anharmonic force constants derived from machine-learning interatomic potentials (MLIPs) are used within a unified Phonopy/Phono3py workflow to compute
phonon dispersions, lifetimes, and
lattice thermal conductivity, providing an internally consistent description of vibrational properties. In nanocrystalline silicon, non-
equilibrium molecular dynamics simulations directly quantify the thermal boundary resistance associated with grain boundaries and reveal its sensitivity to interfacial roughness and the underlying interatomic description. Compared with the Stillinger-Weber and Tersoff potentials, the MLIPs provide a quantitatively accurate and internally consistent description of bulk and interfacial
phonon transport, enabling better predictive modeling of nanoscale thermal transport in low-dimensional materials.
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All authors Houssem Rezgui, Catalina Coll Benejam, Clivia M. Sotomayor Torres, Miguel Pruneda
Optics
Bound states in the continuum in multilayered time-varying metasurfaces
Puneet Garg, Michael Plum and Carsten Rockstuhl
Time-varying metamaterials involve a rapid temporal modulation of the permittivity, often at frequencies comparable to the oscillation frequency of light. However, pronounced physical effects at low modulation amplitudes are observed only when resonances sustained in the metamaterials are utilized. This requires an additional spatial structuring. Here, we demonstrate the first exploitation of bound states in the continuum (BICs) in such spatio-temporal metamaterials consisting of a multilayered metasurface. Leveraging Fabry-Perot BICs in a metasurface-based cavity, we realize polarization-insensitive scattering anomalies such as exceptional points (EPs), coherent perfect absorption (CPA), and lasing at extremely small modulation amplitudes. In a second example, by utilizing
symmetry-protected BICs and breaking time-reversal
symmetry of a multilayered metasurface, we obtain strong nonreciprocal behavior. Harnessing nonreciprocity, we further demonstrate a device capable of one-way monochromatic light transmission at perturbative modulation amplitudes. Our contribution establishes BIC-enabled spatio-temporal metamaterials as a scalable platform for low-power, tunable light-matter interactions, opening new pathways toward practical nonreciprocal photonic devices, dynamic wave control, and on-chip optical signal processing.
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General Relativity and Quantum Cosmology
Linearized Horndeski Theory with a Potential in the Solar System Regime
Hatice Özer
In this paper, the weak-field behavior of linearized Horndeski theory is studied, with emphasis on the role of a scalar potential with a nonvanishing minimum. In this regime, the minimum of the potential acts as an effective source of background
curvature and produces a contribution similar to a cosmological constant. The analysis is restricted to the linear approximation, where nonlinear screening effects such as the Vainshtein mechanism can be consistently neglected. Within this framework, the consistency of the theory with
Solar-System phenomenology in the weak-field limit is examined, and possible deviations from General Relativity depending on the model parameters are discussed. To this end, the linearized field equations for a static point mass are derived, the corresponding geodesic motion is investigated, and the resulting weak-field effects in classical
Solar-System observables, including perihelion advance, light deflection, and gravitational
redshift, are analyzed. The analysis further focuses on the limiting regimes of very light and very heavy scalar fields. In the very light scalar field regime, consistency with
Solar System phenomenology requires sufficiently large values of the coupling parameter
zeta, thereby suppressing the scalar contribution at local scales and keeping deviations from General Relativity negligible. In the very heavy scalar field regime, the scalar-mediated interaction acquires a short range and becomes dynamically suppressed, leading to weak-field predictions that are practically indistinguishable from those of General Relativity. Nevertheless,
geometric terms associated with the minimum of the scalar potential may persist at linear order in the metric perturbations, depending on the value of
zeta.
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Strongly Correlated Electrons
Eclipsing Kitaev: off-diagonal exchange governs the correlated high-field phases of $\beta$-Li$_2$IrO$_3$
Vikram Nagarajan, Ioannis Rousochatzakis, Yuanqi Lyu et al. (+9 more)
We report a high-field thermodynamic study of the hyperhoneycomb Kitaev material $\beta$-Li$_2$IrO$_3$, using magnetotropic susceptibility to resolve its low-temperature field-angle phase diagram across the principal crystallographic planes in
magnetic fields up to $60$ T. Rather than evolving directly from the low-field incommensurate state into a polarized regime, the system exhibits a strongly direction-dependent sequence of correlated phases. Most notably, for fields in the $ac$-plane, we identify an additional high-field phase that is absent in the other principal planes and exists only within a restricted region of field-angle space. This phase structure is naturally explained by the competition between
magnetic field and bond-directional exchange interactions. Using a
symmetry-based description supported by microscopic calculations within the $J$-$K$-$\Gamma$ model, we show that off-diagonal $\Gamma$ exchange couples the
ferromagnetic and staggered
magnetic orders and thereby stabilizes the observed correlated high-field phases. The measured angular dependence of the critical fields is quantitatively captured by this theory, identifying $\Gamma$ exchange as the key interaction controlling the high-field response. These results clarify why the promise of a field-induced
spin liquid – the notion that suppressing
magnetic order might reveal the underlying Kitaev physics – remains unfulfilled in candidate materials: even when the Kitaev interaction is large, off-diagonal exchange stabilizes
symmetry-constrained correlated phases that instead preempt the polarized state.
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All authors Vikram Nagarajan, Ioannis Rousochatzakis, Yuanqi Lyu, Darian Hall, Augusto Ghiotto, Josue Rodriguez, Koh Yamakawa, James Analytis, John Singleton, Mun K. Chan, Natalia B. Perkins, K. A. Modic
Strongly Correlated Electrons
Charge-transfer gap size and oxygen hole content as two mechanisms controlling $T_c$ in the Emery model
Eleanor M. O'Callaghan, Nicolas Kowalski, A.-M. S. Tremblay et al. (+1 more)
Investigating the drivers of superconducting critical temperature trends in cuprates is crucial for uncovering the mechanism of high-temperature superconductivity. Here we study this problem in the canonical model of the copper-oxygen plane, the Emery model, with cellular dynamical mean-field theory. Using the Zaanen-Sawatzky-Allen diagram as a guiding framework, we systematically quantify how the maximum superconducting critical temperature $T_c^{\rm max}$ depends on the copper-oxygen energy distance and on the local repulsion on the copper orbital. The latter is the dominant variable in varying $T_c^{\rm max}$. Unexpectedly, $T_c^{\rm max}$ is optimized not only near the charge-transfer
insulator to metal boundary, consistent with previous findings, but also deep in the charge-transfer regime, revealing an unexplored mechanism. Then we link model parameters to physical observables, identifying the charge-transfer gap size and the oxygen hole content as two mechanisms controlling $T_c^{\rm max}$. $T_c^{\rm max}$ increases monotonically as the oxygen hole content increases and the charge gap size decreases. Our work provides predictions for proposed realizations of the Emery model with ultracold atoms and a theoretical framework for understanding key experimental trends in hole-doped cuprates.
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All authors Eleanor M. O'Callaghan, Nicolas Kowalski, A.-M. S. Tremblay, Giovanni Sordi
Strongly Correlated Electrons
Correlation of maximum superconducting critical temperature with copper-oxygen energy distance and oxygen hole content in the Emery model
Eleanor M. O'Callaghan, Nicolas Kowalski, A.-M. S. Tremblay et al. (+1 more)
Identifying microscopic parameters that optimize the maximum superconducting critical temperature $T_c^{\rm max}$ in the canonical model of the copper-oxygen plane of cuprates, the Emery model, remains challenging. Using cellular dynamical mean-field theory at finite temperature, we find that for a fixed charge gap size in the parent charge-transfer insulating state, $T_c^{\rm max}$ unexpectedly increases with increasing the copper-oxygen energy distance, as this favors the transfer of electrons from oxygen to copper orbitals. We show that these findings emerge naturally in the Zaanen-Sawatzky-Allen scheme and capture observed trends in hole-doped cuprates. Overall, our study uncovers that $T_c^{\rm max}$ is optimized in the Emery model under three conditions: upon doping a charge-transfer
insulator, close to the charge-transfer
insulator to metal boundary, and deep into the charge-transfer regime. While the first two are well-established, uncovering the third is our core contribution. This finding indicates new paths for optimizing $T_c^{\rm max}$.
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All authors Eleanor M. O'Callaghan, Nicolas Kowalski, A.-M. S. Tremblay, Giovanni Sordi
Plasma Physics
Exact 1D Nonlinear Solutions for Proton-Driven Plasma Wakefields
D. Tsiklauri
We extend the classical 1D nonlinear relativistic
plasma wakefield paradigm to evaluate the pristine fluid profiles driven by intense relativistic
proton trains under the comoving coordinate approximation. Using an intense two-bunch scheme, our adaptive integration model is validated down to machine precision against exact closed-form cold-fluid invariants, confirming that interface boundary corners represent physical step discontinuities in the second potential derivative. Scaling to an $N=100$ micro-bunch train, we resolve macroscopic phase-accumulation and subsequent nonlinear detuning by deriving a closed-form, parameter-free piecewise analytical envelope expression. This solution successfully maps the initial unattenuated quadratic coherent growth alongside the flat asymptotic horizontal saturation horizon governed by nonlinear energy conservation. Furthermore, the framework analytically evaluates the transient envelope overshoot, tracking its decay onto the saturation boundary via an exact phase-slip integration length scale. Providing immediate, ready macro-envelope bounds, this computationally inexpensive tool eliminates empirical adjustments and yields a robust mathematical baseline designed to guide and accelerate complex, multi-dimensional particle-in-
cell (PIC) simulations through rapid parameter space exploration before deploying heavy computational assets. It establishes an efficient foundation to optimize asymmetric, custom-shaped driver profiles required to break the fundamental symmetric
transformer ratio limit of 2 to make current particle accelerators more efficient.
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