Quantum Physics
The Hidden Subgroup Problem in Semidirect Products and Quasi-Hamiltonian Groups
Mauro E.S. Morales
Several early
quantum algorithms, including Simon's
algorithm and Shor's period-finding are instances of the hidden subgroup problem (HSP) over finite abelian groups. No
polynomial-time
quantum algorithm is known for the HSP over arbitrary non-abelian finite groups. The non-Abelian case is of particular interest because some instances, such as the dihedral and symmetric group HSPs, are connected to
lattice problems and graph isomorphism, respectively. In this work, we give
polynomial-time
quantum algorithms for two further families containing non-Abelian groups. First, we consider groups of the form $G=A\rtimes_{\varphi} \mathbb{Z}_{p^k}$, with $A$ finite Abelian, $p$
prime, $k\in \mathbb{N}$ and the action of $\mathbb Z_{p^k}$ is generated by the scalar
automorphism $a\mapsto\mu a$, for some $\mu\in\mathbb Z_{\operatorname{Exp}(A)}^\times$, where $\mathrm{Exp}(A)$ is the exponent of $A$. Our
algorithm is efficient when $A$ has bounded generator rank and $\mathrm{Exp}(A)/p=\mathrm{polylog}(|G|)$. This includes the case $A=\mathbb{Z}_N$ for $N\in\mathbb{N}$ and $k=1$, studied by Bacon, Childs and van Dam (FOCS 2005), and $A=\mathbb{Z}_{q^r}$ with $q$
prime and $r\in \mathbb{N}$ studied by van Dam and Dey (TQC 2014). Second, we give a
polynomial-time
quantum algorithm for finite quasi-
Hamiltonian groups under a mild assumption on the input structure. Quasi-
Hamiltonian groups are finite nilpotent groups with modular subgroup
lattice, or equivalently the finite groups in which every subgroup is permutable. As far as we know, this is the first
quantum algorithm to exploit the modularity of the subgroup
lattice for solving the HSP. This extends, under the aforementioned structured input assumption, the
quantum algorithm for Dedekind groups given by Hallgren, Russell, and Ta-Shma (SIAM J. Comput. 32, 2003).
Read the full abstract ▾
Materials Science
Nitrogen Vacancy Centers in Hexagonal Diamond Exhibit Long Coherence Times
Gabriel Kumar, Siyuan Chen, Victor Wen-zhe Yu et al. (+1 more)
We show that negatively charged nitrogen-vacancy (NV) centers in the hexagonal diamond polymorph lonsdaleite offer a route to
spin qubits with enhanced coherence relative to their cubic-diamond counterparts. Using first-principles calculations, we examine two distinct defect configurations, AA, with the same
symmetry as in cubic diamond and AB, with reduced
symmetry. We find that the AB configuration of the NV center exhibits a finite transverse zero-field splitting, giving rise to an approximate fourfold enhancement of the Hahn-echo coherence time $T_2$ at zero
magnetic field. The AA configuration, by contrast, closely reproduces the electronic structure and coherence properties of the cubic NV center. We further characterize the many-body electronic structure, vertical excitation energies, and photoluminescence spectra of both configurations, providing spectral fingerprints for their experimental identification. Our results establish
symmetry-broken NV centers in lonsdaleite as promising candidates for
quantum sensing and information science applications.
Read the full abstract ▾
All authors Gabriel Kumar, Siyuan Chen, Victor Wen-zhe Yu, Giulia Galli
High Energy Astrophysical Phenomena
AT2025agpz in Rubin commissioning data: distinguishing a luminous interacting supernova from nuclear transients in compact galaxies
C. R. Angus, M. Quilt, H. F. Stevance et al. (+37 more)
The Vera C. Rubin Observatory's Legacy Survey of Space and Time will discover unprecedented numbers of rare, long-lived optical transients, many of which will be too faint or too numerous for comprehensive spectroscopic follow-up. Characterising objects that span the boundaries between established transient classes is therefore essential for improving photometric classification. We present AT2025agpz, a luminous transient at $z=0.147$, discovered around peak by ATLAS but extensively monitored during Rubin commissioning observations of the Euclid Deep Field South. The transient is coincident with the
nucleus of a faint
dwarf galaxy, exhibits a rest-frame rise time of $77.9\pm1.3$ d, and reaches a peak bolometric luminosity of $6.3\times10^{43}$ erg s$^{-1}$. The exceptional depth and cadence of the Rubin commissioning data, combined with complementary DECam imaging, tightly constrain the explosion epoch and yield an early-time power-law rise of $n=3.33^{+0.33}_{-0.28}$. Follow-up spectroscopy reveals remarkably slow spectral
evolution dominated by narrow Balmer emission, while high-resolution X-shooter observations resolve broad electron-scattering wings and multiple H$\alpha$ emission components characteristic of interaction-powered
supernovae. Spectral energy distribution modelling indicates a low-mass, moderately
star-forming host
galaxy. Although AT2025agpz occupies observational parameter space shared by the recently identified Ambiguous
Nuclear Transient population, its colour
evolution, host environment, and emission-line morphology favour an interaction-powered luminous
supernova. More broadly, this event highlights the growing observational overlap between luminous interacting
supernovae and
nuclear transients, illustrating both the challenges and opportunities for transient classification in the Rubin era.
Read the full abstract ▾
All authors C. R. Angus, M. Quilt, H. F. Stevance, M. Nicholl, S. J. Smartt, P. Wiseman, A. Möller, C. T. Murphey, P. J. Pessi, K. Auchettl, M. Dennefeld, M. Dominik, C. Frohmaier, P. Francis, M. Gromadzki, A. Lawrence, G. Leloudas, C. Lidman, D. Magill, I. Mandel, B. Martin, S. Mattila, G. Narayan, F. Onori, S. R. Oates, H. M. L. Perkins, L. Rauf, A. Rest, S. Romagnoli, R. Roy, S. Schulze, X. Sheng, K. W. Smith, K. de Soto, P. M. Veres, M. E. Verrico, A. Wasserman, R. Williams, Ł. Wyrzykowski, D. R. Young
Quantum Physics
Machine learning for sample-based quantum diagonalization: a review of generative configuration recovery and the classical-simulability frontier
Nicolás Bonilla Vargas
Sample-based
quantum diagonalization (SQD), equivalently
quantum-selected configuration interaction (QSCI), has become a centre of
gravity of pre-fault-tolerant
quantum chemistry: a processor samples electronic configurations and the
Hamiltonian is diagonalized classically in the resulting subspace. Accuracy is governed entirely by which configurations enter it – a machine-learning selection problem, made acute by a coupon-collector bottleneck. We review the generative and learned selectors by what each generates and the signal it exploits, and identify one gap: no reward-proportional generative-flow-network proposer has been built for tail discovery. On the field's central question – whether the
quantum sampler beats classical selected CI – the negative verdict is not ours to claim: priority belongs to Reinholdt et al. [JCTC 21, 6811 (2025)], and
polynomial-time classical estimation of the flagship
circuits has reinforced it. We state that verdict at the precision a falsifiable claim requires – it concerns reproducible, same-active-space comparisons on molecular electronic structure – and weigh the claims outside those qualifiers. We show that alpha-string weights are not invariant under rotations inside degenerate orbital shells, so determinant counts are undefined until the orbital gauge is declared. We distil a ten-element benchmarking standard and apply it to our own deposit, which returned defects that changed numbers printed here and retracted one from v1. FCI-exact experiments confirm one prediction and refute another: the single generative advantage we find keeps no consistent sign along the dissociation coordinate at device-calibrated noise and reverses under a symmetric readout model. It does beat a noise-matched classical recovery loop on N2 by a margin five seeds cannot resolve, and loses by over a factor of two to a classical selector that needs no sampler.
Read the full abstract ▾
Quantum Physics
Unidirectional Dark-to-Bright Rescue in Cavity-Coupled Quantum Transport
Jack Diab, Arpit Arora, Taylor L. Patti et al. (+1 more)
Strong light-matter coupling in optical microcavities can transport energy ballistically across an emitter array, but the same coupling buries most of the excitation in a
manifold of dark states that grows with system size and traps energy outside the transport channel. We show that the off-diagonal (non-Condon) part of the
exciton-
phonon coupling opens a one-way escape route from this trap, driving population irreversibly from dark states into the radiative channel. This rate is fixed by a photonic-weight conservation law rather than by dark-bright overlap which evacuates the dark
manifold at a rate independent of system size. The mechanism contributes to transport with near-complete efficiency with four signatures being single exponential dark state decay, a size scaling efficiency gap, distinct temperature behavior, and a resonance in the escape rate at vibrational bath modes. Beyond polariton transport, it recasts dark states from a parasitic loss channel into an engineered dissipative resource, with implications for light harvesting and dissipation based
quantum control.
Read the full abstract ▾
All authors Jack Diab, Arpit Arora, Taylor L. Patti, Prineha Narang
Mesoscale and Nanoscale Physics
Topological Charge-Transfer Excitons
Huiyuan Zheng, Kaijie Yang, Ting Cao et al. (+1 more)
Excitons possess internal structure absent from single-particle Bloch particles, allowing their band
topology to emerge from the bound-state structure rather than being inherited from their constituents. This raises the question of how the internal structure of a bound state can provide a microscopic origin of
exciton topology. Here we show that the real-space
embedding of charge-transfer
excitons can generate an intrinsic
manifold of
symmetry-related off-site composite orbitals whose coupling supports topological
exciton bands. Lateral electron-hole separation embeds the localized
exciton on the bond connecting its constituent sites rather than on either site. We demonstrate this mechanism in a honeycomb
lattice, where three bond-centered charge-transfer
exciton orbitals form a Kagome
lattice. By solving the Bethe-Salpeter equation, we show that this emergent multi-orbital
manifold supports a topological
exciton flat band upon time-reversal
symmetry breaking, even when the electron and hole bands are topologically trivial. The resulting band exhibits nearly uniformly distributed
quantum geometry, favorable for interaction-driven bosonic states. Our results establish a general route toward topological bands of localized composite bound states and unconventional strongly correlated bosonic phases.
Read the full abstract ▾
All authors Huiyuan Zheng, Kaijie Yang, Ting Cao, Di Xiao
Quantum Physics
Quantum channel learning with limited parallel access
Mahadevan Subramanian, Hyukgun Kwon and Liang Jiang
Quantum channels can be characterized by their action on an orthogonal operator basis, where these operators are related to observable properties of the
quantum system. For qudit and multimode bosonic systems, this is encoded respectively in the Heisenberg–Weyl transfer
matrix estimated from the Choi-state, and in the characteristic-function transfer map estimated from a two-mode squeezed
vacuum based Choi-state. We derive sample-complexity bounds for estimating entries of the transfer
matrix/map to additive accuracy $\epsilon$ with success probability $\ge1-\delta$, under different resources: access to the complex-conjugate channel $\mathcal{E}^*$ and/or parallel access to $c$ copies. In all settings, the learner uses parallel channel calls with adaptively chosen, ancilla-assisted input states and measurements. Absolute values of transfer-
matrix entries can be learned efficiently with simultaneous access to $\mathcal{E}$ and $\mathcal{E}^*$, with tight scaling $\epsilon^{-4}$. Without conjugate access, any $c<d$ copies are insufficient for efficient learning, requiring sample complexity exponential in the number of ($d$-level) qudits $n$ (for
prime $d$). Efficiency is recovered at $c=d$, with tight scaling $\epsilon^{-2d}$. For bosonic systems, exponential sample complexity holds in terms of an effective dimension induced by an energy constraint for all $c=O(1/\epsilon)$. Although the task is learning a particular state, these bounds carry stronger implications than standard state-learning bounds since the learner controls the inputs and has ancillary assistance. This establishes a hierarchy of channel-learning resources: self-complex-conjugate channels require two-copy ancilla-assisted access for efficient learning, while for every square-free $d$, some channels require $d$-copy access. As a corollary, we derive tighter lower bounds for state learning with limited multi-copy access.
Read the full abstract ▾
Superconductivity
Kinetic Lifshitz invariants and dynamics of nonreciprocal fluctuations in superconductors
Tony Liu, Joaquim Telles de Miranda, Daniel Shaffer et al. (+1 more)
We derive the generalized time-dependent Ginzburg-Landau theory of a disordered noncentrosymmetric
superconductor from the Keldysh nonlinear sigma model, using a two-dimensional electron gas with Rashba
spin-orbit coupling and an in-plane Zeeman field as a minimal model. On the thermodynamic side we construct the Lifshitz invariants of the free energy, the linear and cubic gradient terms and the momentum-odd part of the quartic vertex, and trace their dependence on disorder. These couplings are governed by a single closed-form kernel controlled by the ratio of the Dyakonov-Perel
spin-relaxation rate to temperature, interpolating between the weak-relaxation regime, where the invariants are suppressed, and the relaxation-dominated regime, where the helical modulation of the order parameter saturates at a universal, disorder-independent value. This crossover reconciles conflicting results for the magnetoelectric couplings of dirty Rashba
superconductors. Because the theory is formulated on the Keldysh contour, it also determines the dissipative dynamics: the relaxation rate of a fluctuation with pair momentum $\mathbf{q}$, and hence, by the fluctuation-dissipation
theorem, the Langevin noise power, acquires a term odd in $\mathbf{q}$ and odd in the
magnetic field. The structure of this kinetic Lifshitz invariant is dictated by Onsager reciprocity: friction and noise renormalize in lockstep, so equal-time fluctuations remain Gibbsian while the dynamics are nonreciprocal. As applications we compute the superconducting diode efficiency near $T_c$, where the cubic invariant competes with the quartic vertex and with even higher-gradient terms rendered odd by the helical shift, reversing the sign of the diode coefficient, and the fluctuation-induced magnetochiral anisotropy above $T_c$, where the current-resolved nonreciprocal resistance forms a plateau across the Gaussian regime.
Read the full abstract ▾
All authors Tony Liu, Joaquim Telles de Miranda, Daniel Shaffer, Alex Levchenko
Materials Science
Cooperative adsorption and diffusion trapping induced by AlF3 intercalation in graphite
H. Betancourt-Infante, G. Ruano, F. Bonetto et al. (+1 more)
Graphite's structural and electronic response to molecular intercalation is central to its performance as a carbon-based electrode material, yet the microscopic coupling between subsurface intercalation and surface adsorption remains poorly understood. We present a first-principles investigation of AlF3 adsorption and intercalation in graphite to explain the microscopic origin of a recently observed two-step self-limiting sorption mechanism. Using density functional theory (DFT-D3), we show that a single intercalated AlF3 molecule locally transforms the structure, electronic properties, and
diffusion behavior of graphite through a blister-like surface deformation. Comparing pristine graphite with a graphite surface containing a subsurface intercalated molecule, coverage-dependent adsorption energetics reveal a crossover from repulsive lateral interactions to cooperative binding above the blister, driven by local
curvature and intercalation-induced charge redistribution.
Diffusion-barrier calculations show that the blister simultaneously acts as a kinetic trap, raising
diffusion barriers and transitioning surface mobility from a quasi-barrierless to a thermally activated regime. Charge-density difference and Mulliken population analyses identify the intercalant as a stable electronic reservoir that deepens the surface potential landscape, kinetically immobilizing adsorbed species. Together, these results establish a structure-property relationship for intercalation-induced deformation in graphite, offering a quantitative framework for controlling intercalation efficiency in carbon-based energy storage and conversion systems.
Read the full abstract ▾
All authors H. Betancourt-Infante, G. Ruano, F. Bonetto, S. J. Rodríguez-Sotelo
High Energy Physics (Phenomenology)
GOOFy-compatible 3HDMs and beyond
I. de Medeiros Varzielas and A. Kunčinas
Beyond conventional
Higgs-family and general CP transformations, one may also consider a broader class of non-standard "GOOFy" transformations, in which the scalar fields and their conjugates are assigned related but inequivalent transformations. Although these transformations are not
symmetries of a full Lagrangian in the conventional sense, some nevertheless stabilise the scalar potential. Their impact on the quadratic sector has not yet been systematically classified. We develop a sign-orbit technique to determine the bilinear structures compatible with these transformations. Applied to three-
Higgs-doublet models, and formulated so as to extend to larger multi-
Higgs sectors, the method shows that a non-vanishing GOOFy-compatible quadratic sector exists only when two independent conditions are met: the underlying group admits a non-trivial sign character, and that character is realised within the tensor product of the scalar representation and its conjugate. As a key consequence, we demonstrate that the renormalisation-group stability of the $r_0 \to -r_0$
manifold in isolation is not a generic feature of multi-
Higgs potentials, but rather a direct consequence of special algebraic properties of $SU(2)$. These results provide a classification of the admissible GOOFy quadratic structures and their invariant bilinear subspaces, highlighting the algebraic obstructions to their renormalisation-group stability.
Read the full abstract ▾
Quantum Physics
Identifying slow relaxation in many-body quantum systems through state-graph geometry and state-graph heterogeneity
Heiko Georg Menzler and Tom Ben-Ami
We adapt tools from the theory of
quantum random walks to investigate slow relaxation dynamics through the many-body state graph. Specifically, we construct a probe of heterogeneity between basis states defined using hitting times derived from the
unitary time-
evolution operator. We find that the state-graph geometry, encoded by the pairwise hitting time of basis states, is a highly sensitive indicator of slow relaxation dynamics in a variety of systems. We study three paradigmatic models: the Rosenzweig-Porter model, the
quantum East model, and the triangular
lattice gas model, exhibiting a sudden onset of slow dynamics upon tuning of a control parameter. As a global characterization of the graph geometry, we analyze the spectral radius of the hitting
matrix. We find that it increases sharply at the onset of slow dynamics, spanning many orders of magnitude, with a characteristic crossing point at the transition. Our work provides a
geometric framework for describing and identifying phases with slow relaxation using a unified graph-theoretic formalism.
Read the full abstract ▾
Astrophysics of Galaxies
Expanding stellar associations as Galactic accelerometers
Till Sawala and Núria Miret Roig
The gravitational potential of the Milky Way is fundamental for understanding the
evolution of our
Galaxy and the nature of dark matter. We introduce a new method to constrain the
Galactic potential using expanding young
stellar associations. We exploit the physical constraint that these
stars share a common, compact origin to reconstruct their most likely orbits and infer the gravitational potential in which they have evolved. We define the size of an association using the trace and determinant of its position covariance
matrix. By integrating synthetic associations backward in different trial potentials, we show how the true potential can be identified as the one that minimises these metrics. We demonstrate that, while current observational errors are still too large, upcoming observations will allow us to distinguish between different potentials. Our results suggest that with
Gaia DR4 astrometry and radial velocity errors below 0.2 km/s, the
halo mass can be constrained with a precision of 0.6 trillion
solar masses and the concentration with a precision of < 0.8 using a single association, albeit with significant degeneracies. In addition, we show that the inferred dynamical traceback age is sensitive to the gravitational potential, suggesting that independent age information can help break existing degeneracies, but also that traceback-age estimates are not independent of the assumed potential. Expanding
stellar associations carry information about the gravitational potential in which they have evolved. With the arrival of next-generation astrometry and high-precision radial velocities, they will provide a complementary tool for constraining the
Galactic potential.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
3-form dark energy and cosmic birefringence
Kohei Kamada and Tucker Manton
3-forms are interesting fields to study in the cosmological context for numerous reasons, such as being candidates for explaining inflation and dark energy. The background
evolution of a 3-form field is similar to but distinguishable from a scalar field in an expanding universe, and its tensorial structure allows for unique couplings that cannot be experienced by canonical scalars. In this work, we explore the possibility that 3-form dark energy can explain
cosmic birefringence. We consider two EFT-inspired couplings between the 3-form and the
photon, and compute the birefringence angle $\beta$. We find that a dimension-6 gauge-invariant operator necessitates an extremely large coupling to explain $\beta\sim0.3^\circ$, the value suggested by observations of recent
cosmic microwave background radiation. Conversely, a dimension-4 operator can accommodate $\beta\sim0.3^\circ$ at the expense exciting the longitudinal mode of the
photon. Interestingly, demanding a self-consistent decoupling limit implies the
photon mass lies within a few orders of magnitude of $H_0$. We also derive `universal' profiles for $\beta(z)$, finding the $\beta$ from the dimension-4 operator is insensitive to the form of the 3-form potential but is sensitive to the initial conditions. Contrarily, the dimension-6 operator is highly sensitive to the form of the potential. We finally compare the universal profiles to that of
axion-like particle (ALP) dark energy and an ultralight massive 3-form, the latter obtained from numerically integrated cosmological histories consistent with $\Lambda$CDM up to low
redshift. Our results show that birefringence from 3-form dark energy can both mimic that from an ALP or be distinguishable, depending on the field configuration in the early universe.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Summary statistic for pulsar timing arrays
Gabriela Sato-Polito, Matias Zaldarriaga and Barak Zackay
The timing residuals produced by gravitational-wave signals can be described as an incoherent (
pulsar term) contribution and a coherent (Earth term) map on the sky, which PTAs measure at the locations of the timed
pulsars. The observed Earth term map and the variance induced by the
pulsar term contain all of the information about any GW signal available to a PTA (assuming
pulsar distances are unknown). Furthermore, any type of signal produces on average the same angular correlation function, the Hellings and Downs curve, which decays steeply with multipole as $C_\ell \propto 1/[(\ell+2)(\ell+1)\ell(\ell-1)]$. This suggests that the signal is inherently low-dimensional and therefore only a small number of parameters are needed to fully characterize it. We present an expression for the PTA likelihood that makes the dependence on the Earth term map and
pulsar term variance explicit, and show that only a few spherical harmonic coefficients are needed to capture most of the information about the signal. To quantify this in a realistic setting, we compute the Fisher
matrix of the amplitude of a
stochastic background or a deterministic point source assuming the noise properties and sky locations of the
pulsars in the NANOGrav 15yr
dataset. We find that $\ell_{\rm max}=2$ of the Earth term map and the monopole of the
pulsar term variance retain $\sim 95\%$ of the information about the signal. For a point source, including the dipole of the
pulsar term variance is important to achieve a similar fraction.
Read the full abstract ▾
Strongly Correlated Electrons
Self-dual $S_3$ gauge theory in 2+1d: lattice model and topological phase transitions
Da-Chuan Lu, Chong Wang and Ashvin Vishwanath
Electric-
magnetic self-duality of the $\mathbb{Z}_2$ gauge theory, realized microscopically as a half-
lattice-translation exchanging electric charge and
magnetic flux, has been an influential example of a duality
symmetry with an exact
lattice realization. We construct the first non-Abelian generalization of this construction: a
lattice model of the $S_3$
quantum double $\mathcal{D}(S_3)$ on a tensor product
Hilbert space in which the $\mathbb{Z}^{\mathrm{em}}_2$ anyon-permutation
symmetry, exchanging the non-Abelian chargeon $C$ and fluxon $F$, is realized via
lattice translation. Consequently we find that the zigzag boundary termination of the model realizes, without fine-tuning, a gapless critical edge state described by the tetracritical Ising CFT. The bulk admits three independent $\mathbb{Z}_2^{\mathrm{em}}$-preserving bosonic perturbations, driving $\mathcal{D}(S_3)$ into distinct gapped phases. We analyze these transitions by three independent methods: category-theoretic anyon condensation, microscopic
lattice Hamiltonians, and Chern-Simons-
Higgs theory, which all agree, yielding a unified picture. These examples motivate a minimal-condensation principle: proliferating a bosonic anyon generically drives condensation of a minimal condensable
algebra containing it, with
symmetry-related condensates appearing as degenerate
vacua that spontaneously break the anyon-permutation
symmetry. Our model construction extends to an infinite family of self-dual dihedral
quantum doubles $\mathcal{D}(D_{2n})$. Notably, each model is sign-problem-free, opening the door to large-scale numerical exploration of the phases of non-Abelian Chern-Simons-
Higgs theories.
Read the full abstract ▾
Disordered Systems and Neural Networks
Entangling power of neural networks
Taige Wang, Nisarga Paul and Liang Fu
Characterizing the complexity of correlations between subsystems is a fundamental task across information theory, machine learning, and science. In
quantum physics, neural networks have found increasing application in learning wavefunctions. Here we introduce the entangling power of an encoder-decoder neural network, which quantifies its ability to generate
entanglement between subsystems, dependent on a latent space dimension $K$ and the complexity class of the decoder. We exactly calculate this quantity for
polynomial decoders of degree $p$ acting on a $K$-dimensional latent space. Our results establish the exponential entangling power of neural networks with modest resources. More broadly, our work provides a framework for analyzing correlations in machine learning that generalizes the notion of the Schmidt rank in
entanglement theory.
Read the full abstract ▾
General Relativity and Quantum Cosmology
Absorption spectrum and greybody factors of charged black holes in loop quantum gravity
Marco A. A. de Paula, Valdir B. Bezerra and Luiz C. S. Leite
In the last few decades, singularity-free black holes (BHs) obtained in the framework of Loop
Quantum Gravity (LQG) have gained
attention in the literature. These compact objects replace the classical singularity with a transition hypersurface called the bounce radius and stand out as potential scenarios for exploring the imprints of LQG in BH physics. Although scalar perturbations in the vicinity of LQG-based BHs are currently being studied, the absorption spectrum has not yet been analyzed in detail. In this work, we present an in-depth investigation of the absorption properties of massless test scalar fields by a charged LQG BH, aiming to better understand the role played by the
quantum and charge parameters of the BH spacetime. Using a numerical approach, we compute the absorption cross section (ACS) of the massless scalar wave for arbitrary values of the frequency of the incident wave. We find that the behavior of the ACS as we increase the
quantum parameter indicates that the peaks and troughs of the total ACS exhibit opposite behaviors, i.e., the curve related to the highest peak corresponds to the deepest troughs. Moreover, we show that the ACS decreases as we consider higher values of the BH charge-to-mass ratio. This is in stark contrast to the behavior of the absorption spectrum as we vary the
quantum parameter. We also draw comparisons with the Reissner-Nordstrom (RN) BH, exploring the situations where LQG and RN BHs can have the same absorption properties. Furthermore, we find excellent agreement between our numerical results and the well-known classical and semiclassical approximations for the total ACS in their corresponding limits. For completeness, we also investigate the greybody factors. Our results can be viewed as a first step toward a better understanding of the absorption properties of LQG-inspired BHs.
Read the full abstract ▾
High Energy Physics (Theory)
Adiabatic Deformations of Black Hole Moduli: II. The Magnetic GHS Family
Karim Benakli and Anna Chrysostomou
We study the leading adiabatic response of
magnetic GHS black holes in massless Einstein-Maxwell-dilaton theory to a prescribed exterior modulus varying slowly in advanced time. In ingoing Eddington-Finkelstein coordinates with the exact areal radius, we derive the time-dependent spherical equations and expand about a slowly evolving instantaneous static GHS representative, keeping its horizon distinct from the exact dynamical marginal horizon. The
magnetic GHS family realizes the canonical-slice and Fredholm framework developed in the companion paper. Its integrability yields in closed form the canonical tangent, the finite-rank source profile, a horizon-regular solution of the auxiliary inhomogeneous equation, and a globally regular generator of the sliced-operator kernel. For the leading Robin functional arising in the massless large-radius overlap, we evaluate the Fredholm denominator analytically and prove that it is strictly positive on the charged non-extremal branch. This remains true where the conventional normalization of the kernel generator degenerates, showing that these loci are normalization singularities rather than degeneracies of the kernel mode. Within the controlled large-radius overlap regime, this positivity proves existence and uniqueness of the completed leading-order quasi-static near-zone problem. We then solve the forced radial equation explicitly. The scalar lag is the sum of a universal forced profile and a sliced homogeneous mode whose amplitude is fixed by the exterior matching datum. The mass lag follows algebraically from the radial constraint, and the lapse lag from a single elementary quadrature. The exact marginal horizon is recovered from the lag-corrected solution. The result gives the complete leading quasi-static near-zone response, exact in its radial dependence, for every admissible exterior datum within the specified massless overlap model.
Read the full abstract ▾
Quantum Gases
Exact statistical transmutation of quantum mixtures on a ring
Wayne J. Chetcuti, Nathan Goldman, Patrizia Vignolo et al. (+1 more)
One-dimensional strongly repulsive
quantum mixtures exhibit non-trivial exchange statistics arising from the interplay between orbital and
spin degrees of freedom. Using an exact solution, we demonstrate that in the single-
impurity limit the wavefunction of
Fermi-
Fermi and Bose-Bose mixtures on a ring threaded by an artificial gauge field display exact anyonic statistics under exchange of the
impurity with the majority particles. The resulting fractional exchange phase is fixed by the angular momentum sector selected through the applied flux. We find that the
impurity momentum distribution coincide exactly with the anyonic one, independently of the bosonic or fermionic nature of the mixture, with the large-momentum tails encoding a direct signature of the anyonic statistical angle. Finally, we devise a quench protocol for reversible dynamical anyonization. Our results provide a path for realizing and manipulating anyonized states with ultracold atoms.
Read the full abstract ▾
All authors Wayne J. Chetcuti, Nathan Goldman, Patrizia Vignolo, Anna Minguzzi
Statistical Mechanics
Theory of Measurement-Altered Criticality
Kabir Khanna, Sara Murciano and Romain Vasseur
Local measurements can alter long-range correlations in gapless
quantum matter. We propose a theory of weakly-monitored Tomonaga-Luttinger
liquids, a broad class of
quantum critical states in one dimension. In order to address the intrinsic randomness of the measurement record, we develop a replica instanton calculation to study Born-averaged observables. We find that when measurements are relevant, average correlators of density and phase fluctuations decay at long distances as universal power laws with logarithmic corrections, a feature we argue is peculiar to measurement-induced randomness. We characterize the full multifractal spectrum of moments of correlations functions, revealing broad, strongly non-gaussian fluctuations across the ensemble of post-measurement states. We support these analytic results with
matrix-product-state calculations, and provide a general picture of measurement-altered criticality for ground states described by 1+1d conformal field theories. Our results establish that physical measurements alter critical
quantum states in a manner that lies beyond both forced measurements and conventional critical scaling.
Read the full abstract ▾
Earth and Planetary Astrophysics
Size Constraints for the Pre-atmospheric Parent Bodies of Ordinary Chondrites
Juan A. Sanchez, David C. Cantillo, Adam Battle et al. (+7 more)
The study of S-complex near-Earth objects (NEOs), the parent bodies of ordinary chondrites, has shown that they are dominated by asteroids with LL chondrite-like compositions. This is surprising because among the three subtypes of ordinary chondrites (H, L, and LL), LL chondrites are the least common, representing only 10% of all ordinary chondrite falls. This discrepancy has been attributed to the size of the NEOs studied, which are likely too large to be the immediate precursors of the meteorites that fall on Earth. To test this hypothesis, we obtained near-infrared spectra (0.7-2.5 $\mu$m) of a group of objects with absolute magnitudes 20.0 $\leq$ $H$ $\leq$ 29.2 (sizes $\sim$4-343 m). The sample was divided into subgroups based on their $H$ value, and the composition of the asteroids was determined. We found that the dominance of LL chondrite-like objects disappears at sizes of $\sim$31-49 m. At this size range, asteroids with L chondrite-like compositions become dominant, matching the fraction of L chondrite meteorite falls. In contrast, the fraction of H chondrite-like NEOs was found to be much lower than the proportion of H chondrite falls, even among the smallest objects. We determined an upper size limit of $\sim$18 m for the parent bodies of these meteorites. The same upper limit was established for the pre-atmospheric parent bodies of LL chondrites. These results constitute the first observational evidence for a size dependence in the composition of S-complex NEOs.
Read the full abstract ▾
All authors Juan A. Sanchez, David C. Cantillo, Adam Battle, Miren Miranda, Benjamin N. L. Sharkey, Tanner S. Campbell, Rogerio Deienno, William F. Bottke, David Nesvorný, Vishnu Reddy
Quantum Physics
Scalable Circuit Cutting: A Framework for Combined Gate and Wire Cuts Using Gate Groups
Fiona Jiali Fröhler, Yannick Stade, Christian Ufrecht et al. (+2 more)
Quantum circuit cutting enables the execution of large
circuits on devices with a limited number of
qubits by partitioning
circuits into independent subcircuits. However, this introduces a sampling overhead, which grows exponentially with the number of cuts, rendering the choice of cut placements critical for practical
circuit cutting. Determining optimal cut placements remains computationally challenging, particularly as
circuits grow in size. Additionally, existing
circuit cutting approaches typically treat gate and wire cuts independently. Those combining both cutting approaches, however, do not take advantage of joint cutting, i.e., identifying common gate groups and cutting them jointly for a reduced overhead. This work presents a unified framework that combines gate and wire cutting within a single partitioning strategy, enabling more efficient
circuit decompositions. Moreover, our approach incorporates joint cutting via a novel gate grouping technique, further reducing sampling overhead. By formulating the cut placement problem as a scalable graph partitioning task, our method efficiently identifies near-optimal cut placements for large
circuits, also providing diagnostic feedback on whether
circuits are suitable for cutting.
Read the full abstract ▾
All authors Fiona Jiali Fröhler, Yannick Stade, Christian Ufrecht, Daniel D. Scherer, Robert Wille
Astrophysics of Galaxies
Variations in the 3.3 ${\mu}$m Polycyclic Aromatic Hydrocarbon Feature Across Nearby Galaxies Driven by Metallicity and Radiation Field Spectrum
Hannah B. Koziol, Karin Sandstrom, Dalya Baron et al. (+29 more)
We use JWST NIRCam imaging to investigate the 3.3 ${\mu}$m polycyclic aromatic hydrocarbon (PAH) feature in nearby
galaxies. NIRCam observations of the 3.3 ${\mu}$m feature are emerging as a powerful tool for studying the structure of the interstellar medium (ISM) and the conditions of the
dust at ~0".1 resolution. These maps require accurate subtraction of the underlying continuum emission. We present an empirical method to isolate the PAH-correlated emission in the F335M filter using the F300M and F360M filters for continuum subtraction. We find that the slope of the F335M/F300M versus F360M/F300M colors for PAH-correlated emission shows a dependence on local ISM properties, with the strongest dependence on specific
star formation rate. Weaker emission features captured by these bands appear suppressed relative to the main 3.3 ${\mu}$m feature in regions of active
star formation. We find trends in the 3.3/7.7 and 3.3/11.3 ${\mu}$m ratios that suggest changes in PAH size, charge, and heating by a varying radiation field spectrum. We find decreases in both band ratios with increasing
metallicity, which we attribute to a shift to smaller PAH populations at low
metallicity. Comparison to optical ionized gas line ratios and
dust models show that variations in the interstellar radiation field spectrum influence the PAH feature ratios. This analysis supports inhibited growth formation scenarios for the observed PAH band ratio trends with
metallicity and emphasizes the importance of considering the local radiation field characteristics and gas-phase
metallicity when using these band ratios as PAH property diagnostics.
Read the full abstract ▾
All authors Hannah B. Koziol, Karin Sandstrom, Dalya Baron, Adam K. Leroy, Jérémy Chastenet, Ryan Chown, Daniel A. Dale, Oleg V. Egorov, Lindsey Hands, Mansi Padave, Debosmita Pathak, Erik Rosolowsky, Jessica Sutter, Tony D. Weinbeck, Thomas G. Williams, Alberto Bolatto, Médéric Boquien, Yixian Cao, Enrico Congiu, Simon C. O. Glover, Hwihyun Kim, Ralf S. Klessen, Kirsten L. Larson, Justus Neumann, Elias K. Oakes, Hsi-An Pan, Ismael Pessa, Sumit K. Sarbadhicary, Benjamin W. Stadel, Jiayi Sun, David A. Thilker, Leonardo Úbeda
High Energy Physics (Theory)
$N$-Photon Amplitudes in EFT from Recursion Relations and Effective Vertices
Gustavo Bispo and Sylvain Fichet
We present a recursive framework for computing arbitrary tree-level helicity amplitudes in the general effective field theory (EFT) of electromagnetism. We show that
photon amplitudes can be constructed using a CSW-like recursion, whose building blocks consist of purely local subamplitudes. For a fixed number of external legs, only a finite number of these contact amplitudes need to be computed, and these admit compact expressions in terms of Hafnians. We further show that the contact amplitudes are encoded in an effective contact Lagrangian, that can be computed systematically from the general EFT Lagrangian using a suitable generating functional. We provide this contact Lagrangian up to $N=14$
photons. We argue that the contact Lagrangian reveals the hidden simplicity of helicity-conserving amplitudes, providing a simple proof of the equivalence between off-shell electromagnetic duality and helicity conservation. We further show how to resum the contact Lagrangian of a helicity-conserving theory to all $N$, and illustrate the procedure for Born-Infeld (BI) electromagnetism. Building on these methods and results, we compute the complete 6-point and 8-point tree-level helicity amplitudes generated by generic EFT operators, and the tree amplitudes up to 10-point in BI electromagnetism.
Read the full abstract ▾
High Energy Physics (Phenomenology)
Novel Signatures of Matter-Induced Dark Matter Decay in Large-Volume Neutrino Telescopes
Hooman Davoudiasl, Dan Hooper and Samyak Jain
Large-volume
neutrino telescopes offer a unique opportunity to search for decaying dark matter through events containing a pair of energetic, highly non-collimated
muon tracks emerging from a common vertex. Such events would have negligible Standard Model backgrounds and would constitute a striking signature of new physics. Conventional dark matter annihilation or decay, however, is too strongly constrained to produce an observable rate of such events. We therefore consider scenarios in which an excited dark matter state is extremely long-lived in
vacuum but decays much more rapidly in the presence of ordinary matter. We present two realizations of this mechanism. In the first, a long-range scalar field sourced by ordinary matter modifies the dark-sector mass spectrum, kinematically opening the decay $\chi_2 \rightarrow \chi_1 Z'$ near the Earth while leaving it forbidden in
vacuum. In the second, the scalar background induces kinetic mixing between a heavy $Z'$ and the
photon, greatly enhancing the three-body decay $\chi_2\to\chi_1\mu^+\mu^-$ in matter-rich environments. We calculate the resulting distributions of
muon energies and opening angles and show that viable regions of parameter space can yield observable event rates in IceCube, KM3NeT, and other large-volume
neutrino telescopes while remaining consistent with existing constraints. We also briefly consider the sensitivity of IceCube to multi-
muon events produced by the decays of cosmologically long-lived charged particles with masses $\gtrsim 1$ TeV.
Read the full abstract ▾
Astrophysics of Galaxies
Emission line formation in scattering dominated media: implications for LRDs
Elisha Modelevsky, Omri Nitzan, Re'em Sari et al. (+1 more)
Recent JWST observations of “Little Red Dots” (LRDs) reveal broad and prominent Balmer emission lines. We present a theoretical framework for intrinsic emission line formation and broadening within static, optically thick, scattering-dominated gas envelopes with thermal populations. Using random-walk and
diffusion approximations, we derive analytical line profiles for lines forming intrinsically within the scattering medium. We demonstrate that a geometrically thin planar photosphere produces a shallow line profile characterized by a logarithmic plateau and a $v^{-1}$ wing. A radially extended photosphere yields a broken power-law spectrum transitioning from $v^{-\alpha}$ to $v^{-(\alpha+1)}$, with $0 < \alpha < 1$. This is in contrast to a scattering medium external to the line-forming region, which produces an exponential line profile. We show that this broken power-law model can fit the $\mathrm{H}\alpha$ line profiles observed in LRDs. Higher quality spectra may be able to distinguish between intrinsic and extrinsic models for the line broadening in LRDs. In our LTE models, the high contrast between the $\mathrm{H}\alpha$ and continuum flux cannot be explained. Quantitative comparison to LRD spectra requires expanding our models to non-LTE situations.
Read the full abstract ▾
All authors Elisha Modelevsky, Omri Nitzan, Re'em Sari, Eliot Quataert
High Energy Physics (Phenomenology)
First-principles upper bounds on dark matter-electron scattering rates from condensed matter sum rules
Bradford A. Barker, Jay Epstein, Luke James et al. (+5 more)
A wide variety of condensed matter systems are used or proposed as detectors to search for dark matter-electron scattering. In general, the scattering rate depends on detailed knowledge of the electronic properties of these systems. However, when dark matter couples to electron density, the dark matter-electron scattering rate can be related to the electron energy loss function, whose integrals are bounded by first-principles sum rules that rely on only a few macroscopic target properties. In this paper, we use these first-principles sum rules to derive upper bounds on the dark matter-electron scattering rate depending on only a few material properties: the
plasma frequency $\omega_\text{p}$, the target mass density $\rho_T$, and the static (longitudinal) dielectric function at finite momentum transfer, $\varepsilon(q, 0)$. The bulk material properties $\omega_\text{p}$ and $\rho_T$ vary only over a limited range across a wide variety of materials, and to a good approximation, the generic large-$q$ dependence of $\varepsilon(q, 0)$ can be understood from a simple scaling law depending only on $\omega_\text{p}$ which we verify with analytic and numerical examples. Thus, our upper bounds are largely material-agnostic, and place a fundamental limit on the sensitivity of any dark matter-electron direct detection experiment probing the coupling to electron density.
Read the full abstract ▾
All authors Bradford A. Barker, Jay Epstein, Luke James, Yonatan Kahn, Elizabeth A. Peterson, Anirudh Prabhu, Tanner Trickle, Samuel L. Watkins
Astrophysics of Galaxies
On the Origin of the Ly$\alpha$ Damping Wing in Galaxies at $8\le z \le 10$: Explorations using the NINJA Simulations
Sukanya Mallik, Raghunathan Srianand and Nishikanta Khandai
Ly$\alpha$ damping wing measurements of
galaxies at $7\leq z\leq14$ with the JWST provide a powerful probe of the Epoch of Reionization. We combine the large-scale cosmological hydrodynamical NINJA simulations with an idealized ionized-bubble model at z=8 and 10 to quantify the contributions of the intergalactic medium (IGM), circumgalactic medium (CGM), and interstellar medium (ISM) to the observed Ly$\alpha$ damping wing. We generate mock Ly$\alpha$ absorption spectra, and consider three idealized scenarios: (i)
galaxies embedded in a uniformly ionized IGM, (ii)
galaxies surrounded by HII regions with radii of 0-400 pkpc, and (iii) the same models including Ly$\alpha$ absorption from partially ionized gas within the virial radius. We explore IGM neutral fractions ($x_{\rm HI}$) of 0.1, 0.8, and 1.0, and compare the distribution of inferred HI column densities (NHI) with observations to constrain the sizes of HII regions and $x_{\rm HI}$ of the IGM and gas in and around
galaxies.
Galaxies are surrounded by over-dense gas extending to $\sim$60-100 pkpc, with its extent increasing with
halo mass and showing little
evolution between z=8 and 10. The inferred NHI also increases with
halo and
stellar mass. While the observed incidence of damped Ly$\alpha$ absorption and the median NHI can be reproduced by different combinations of $x_{\rm HI}$ of the IGM and HII region size, models with a uniformly ionized IGM or HII regions larger than $\sim50$ pkpc fail to reproduce the strongest absorbers (NHI>$10^{22}cm^{-2}$). Including partially ionized gas within the virial radius substantially increases the incidence of these absorbers, although the predicted values remain below the observations, suggesting an additional contribution from unresolved gas in
stellar birth clouds. The strongest damped Ly$\alpha$ absorbers therefore provide a unique probe of the ionization state of the ISM, CGM, and IGM.
Read the full abstract ▾
High Energy Physics (Theory)
Mass and Force Relations for Extremal E2MD Black Holes
Sera Cremonini, Mirjam Cvetič, Christopher N. Pope et al. (+1 more)
We study static extremal black holes in Einstein
gravity coupled to a dilaton and two Maxwell fields with independent dilaton couplings $a$ and $b$. When $b=-1/a$ in four dimensions, a time-symmetric initial-value construction allows us to determine the masses and interaction energies of multi-black-hole configurations. On this special locus, the long-range force between any two extremal black holes vanishes. For arbitrary $a$ and $b$, a constant dilaton-shift
symmetry, together with homogeneity and the extremality condition, yields a first-order ordinary differential equation that determines the extremal mass as a function of the two electric charges. This equation allows us to analyze the force between non-identical extremal black holes without having to know the explicit black-hole geometry. In all analytically controlled regimes that we examine, the locus $b=-1/a$ separates attractive behavior for $b>-1/a$ from repulsive behavior for $b<-1/a$. We extend the analysis to arbitrary spacetime dimensions, where the corresponding force-cancellation condition is $ab=-2(d-2)/(d-1)$. Finally, we test this sign pattern using the exact $A_2$, $B_2$ and $G_2$ Toda black holes. In the $G_2$ case, a potentially problematic branch is excluded because it contains naked singularities outside the horizon, suggesting an intriguing connection between regularity and the sign of long-range forces.
Read the full abstract ▾
All authors Sera Cremonini, Mirjam Cvetič, Christopher N. Pope, Aritra Saha
High Energy Physics (Phenomenology)
Axion-driven spontaneous leptogenesis, precisely
Konstantin Kuckenberg, Martin A. Mojahed, Kai Schmitz et al. (+1 more)
We revisit a minimal scenario for spontaneous leptogenesis where the asymmetry generation is driven by a heavy
axion-like field evolving via standard misalignment. We focus on the simplest framework in which
lepton number violation originates from the dimension-five Weinberg operator and contributions from standard thermal leptogenesis become negligible. The asymmetry is computed by solving a set of transport equations, which incorporate fully
flavor-dependent interaction rates for the Weinberg operator that are presented here for the first time. We also derive a simple algebraic master formula for the generated $B\!-\!L$ asymmetry, valid for arbitrary
axion velocities and classically shift-symmetric couplings to the Standard Model, that reproduces the $B\!-\!L$-production dynamics of the full set of transport equations in controlled parameter regions. Along the way, we quantify the importance of low-scale
neutrino masses and the two mass orderings on the final prediction for the generated asymmetry. Finally, we assess the cosmological viability of different
axion couplings by accounting for
entropy dilution from late-time
axion decays and imposing constraints from baryonic isocurvature perturbations. We demonstrate that explaining the
baryon asymmetry via standard Majoron misalignment is under severe tension due to dilution from late-time decays. In contrast,
axions coupled to strong or weak sphalerons can successfully produce the observed asymmetry for decay constants near the energy scale of grand unification and
axion oscillation temperatures $T_{\text{osc}} \gtrsim 10^{11\cdots12}$ GeV, provided a cosmological history featuring high-scale inflation and efficient reheating.
Read the full abstract ▾
All authors Konstantin Kuckenberg, Martin A. Mojahed, Kai Schmitz, Hidenaga Watanabe