Papers

In the gauge/gravity framework flavor degrees of freedom are introduced to the gauge theory side through the insertion of probe flavor $D$ branes in the supergravity background. Scalar, vector or spinor fluctuations on theses flavor branes perceive neither the background supergravity metric nor the worldvolume-induced metric of the flavor branes. Indeed, they follow an effective metric called the open string metric (OSM). Through a proper choice of worldvolume gauge fields, one can induce a horizon structure in these OSMs. Studying holographic information-theoretic quantities in these kinds of geometries is equivalent to studying information-theoretic quantities in the flavor sector on the gauge theory side. In this article, we have studied various information-theoretic measures like mutual information, entanglement wedge cross-section and entanglement negativity for an open string geometry. All the calculations are done by considering strip-like parallel boundary subsystems for three- and four-dimensional OSMs. We have also measured the change in these mixed-state information-theoretic quantities from the relevant quantities in the pure AdS geometry due to the application of a background electric field.

The recent LUX-ZEPLIN (LZ) experiment analysis reported a high energy nuclear recoil candidate at $E_R \simeq 248~{\rm keV}$, motivating interpretations in terms of inelastic dark matter. We study this event in a pseudo-Dirac fermion model with a vector boson mediator $Z'$, assuming a low-reheating temperature and dark matter production through freeze-in at stronger coupling. In contrast to the thermal freeze-out case, the reheating temperature provides an additional parameter controlling the relic abundance and breaks the one-to-one relation between the dark matter mass and direct-detection cross section. As a result, the LZ candidate can be reproduced over a continuous region of parameter space, including mass splitting below the thermal benchmark.

We study the dynamical scalar tidal Love numbers of wormholes that provide viable mimickers for black holes, focusing on thin-shell Schwarzschild and Damour-Solodukhin geometries. Using a matched near- and far-zone expansion, we determine their tidal response in the low-frequency regime. The presence of a long throat introduces an additional characteristic scale and naturally separates the modes into two classes. Super-throat modes probe the global wormhole geometry and are sensitive to both asymptotic regions, whereas sub-throat modes probe only one side of the wormhole and effectively perceive the throat as a black-hole horizon. We derive the scalar tidal Love numbers analytically for both classes of modes and show that their dissipative parts exhibit distinct low-frequency behavior, reflecting whether one or both potential barriers participate in the scattering process. We further find that, as the wormhole approaches the black-hole limit, the super-throat contribution becomes progressively negligible, while the sub-throat response smoothly reduces to that of a Schwarzschild black hole. These results demonstrate that the tidal response of wormholes depends crucially on whether the perturbation probes the global structure of the throat.

Excitons in magnetic semiconductors have energies and spin structures that are sensitive to the underlying magnetic order. We study this coupling in a minimal one-dimensional lattice model of a conduction electron and a valence hole moving in a ferromagnetic background of localized quantum spins, treating the electron, the hole, and the magnon(s) as explicitly resolved degrees of freedom. At zero temperature, spin conservation closes the relevant Hilbert subspaces at the one- or two-magnon level, so the model can be solved essentially exactly with a real-space Green's function method. Comparison against a frozen-spin approximation in which the local moments are replaced by their ordered values identifies which effects are due to emission and absorption of quantum magnons. A frozen background already lifts the spin degeneracy of the exciton and, if the two carriers couple with different strengths to the local moments, it mixes the singlet with the spin-zero triplet exciton. The emission and absorption of quantum magnons goes qualitatively further: it splits and shifts the exciton energies nonlinearly in the exchange coupling even when all frozen-spin effects vanish; for carriers with unequal hopping integrals, it hybridizes the singlet and spin-zero triplet excitons, thereby brightening the dark triplet; and it increases the exciton radius, which in turn enhances the magnon dressing by removing an on-site cancellation. These quantum effects are therefore strongest for extended, Wannier-like excitons, which is precisely the regime that is commonly modeled assuming a static (frozen-spin) magnetic order.

Kinematic perturbations observed with ALMA in CO line emission provide evidence for a population of embedded giant protoplanets shaping the structure of protoplanetary disks. We present JWST/MIRI F1140C ($\lambda = 11.3~\mu$m) coronagraphic observations of five protoplanetary disks, HD163296, RXJ1615.3-3255, RXJ1842.9-3532, SY Cha, and LkCa 15, with the goal of directly detecting candidate protoplanets orbiting at $\gtrsim$ 70 au previously inferred from gas kinematics. The data were analyzed using a bespoke methodology that combines reference PSF subtraction with forward modeling of partially resolved inner disk emission, which otherwise dominates the diffraction pattern in the images. This approach improves the sensitivity to young companions at small separations. No point source consistent with an embedded protoplanet is detected in any of the systems. Instead, in three systems we detect extended emission at $11.3~\mu$m tracing the outer disk out to radii comparable to those probed by CO. Injection tests indicate upper mass limits of roughly $3-20$ M$_J$ at separations of a few hundred au, assuming no additional thermal contribution from circumplanetary environment. Even with space-based observations, these limits remain mostly above the $\sim1-5$ M$_J$ masses inferred from disk kinematics, largely due to the limitations imposed by emission (and/or scattered light) contributions from both the inner and outer disk. These observations highlight the challenges of observing protoplanets embedded in their forming environment at large separation with JWST/MIRI. Lessons learned can inform future studies with the Extremely Large Telescope, which will probe separations where the occurrence rate of gas giants is expected to be higher.

We prove optimal trace-norm relaxation for the one-dimensional Lindbladian associated with the Witten differential $a=h\partial_x+V'$ which annihilates the classical Gibbs density: if $\lambda_1(h)$ is the first positive eigenvalue of $H=a^*a$, then the relaxation rate is $\gamma_h=\lambda_1(h)/(2h)$. It applies to initial operators whose Schwartz kernels, after a Gibbs conjugation, satisfy $ L^2 $ estimates for the restriction to the diagonal and for the normal derivative. An appendix by Chat GPT 6 presents a stronger result specialised to positive initial data.

We show that, for the unique case of a system of electrons and nuclei in one dimension, the $\hGamma$ operator in phase space electronic structure theory has a zero non-Abelian curl. Using this fact, we are able to show that a phase space electronic structure framework in Wigner space has a one-to-one mapping to the exact fully quantum vibronic Hamiltonian. In other words, one loses no information by working within the framework of phase space electronic structure theory rather than Born-Huang theory; the only difference is that, whereas Born-Huang theory represents the total vibronic Hamiltonian as a quadratic order expansion in $\hbar$, the Hamiltonian becomes an infinite order expansion in $\hbar$ within a phase space electronic structure framework (a so-called "Generalized Born-Huang" approach). That being said, numerical results at first or second order demonstrate that, for a limited number of electronic states, phase space electronic structure theory strongly outperforms Born-Huang theory – a result that justifies a great deal more research into this novel electronic structure approach.

Kohn-Sham density functional theory (DFT) remains the workhorse of ab initio materials simulation, yet cubic computational and quadratic memory scaling have confined calculations to a few hundred to thousands of atoms, spanning only nanometers, far below experimentally relevant length scales. We introduce XLSDFT, a linear-scaling DFT framework based on divide-and-conquer decomposition of the one-particle density matrix and Chebyshev-filtered subspace iteration, achieving linear computational and memory scaling while retaining DFT accuracy. Deployed on the LineShine exascale supercomputer, XLSDFT reduces computational complexity by orders of magnitude, enabling unprecedented DFT scale: a 200-million-atom silicon crystal, twentyfold beyond the prior record. Our implementation achieves 96.6% weak-scaling efficiency and sustained 157.9 Pflop/s (FP64) for a 100-million-atom scaling study. We further simulate an 11-million-atom all-solid-state battery interface of unprecedented complexity, 1,000 times beyond prior DFT for such systems, revealing how lithium metal reacts with the solid electrolyte at atomic resolution, in quantitative agreement with spectroscopy experiments.

Active disordered solids including dense human crowds and epithelial cells under confinement exhibit striking system-scale oscillatory spatiotemporal patterns. These are linked to a local feedback mechanism, self-alignment, that aligns the direction of a particle's motility vector to the total force. Simulations and experiments of solids made of such agents show these spontaneous oscillation patterns. Theoretically, they have been linked to both a nonlinear bifurcation and to selection of long-wavelength normal modes. Here we derive a closed nonlinear equation for the displacement field of active self-aligning 2d solids subject to angular noise. Along the normal modes of the solid, the dynamics of the mode amplitudes correspond to nonlinearly damped and stochastically driven harmonic oscillators. To linear order, we show that the system transitions from Active Brownian type correlated motion to oscillatory motion that increasingly condenses onto the lowest modes of the solid. We compare the analytical predictions for the mode spectra with simulations, finding excellent agreement approaching the transition from the disordered side. Strong nonlinearities manifest deep in the oscillating phase at strong alignment and small noise, consistent with the previous observations. At the continuum level, we derive a closed-form nonlinear wave equation for self-aligning solids. The transition to undamped oscillations is a second order dynamical phase transition driven by the competition between noise and alignment. At the linear level, we predict travelling acto-elastic waves, together with the emergence of system-scale oscillations for confined systems, consistent with observations in tissues and crowds. Our framework extends the understanding of self-aligning solids, which are pervasive among artificial and biological systems across multiple scales.

Surface modification is an important strategy for tailoring the physical and chemical properties of materials for advanced technological applications. In thin films, changes in surface structure, roughness, and composition can strongly influence their functional behavior. In this work, we studied the effect of N+-ion irradiation at 20 keV energy on Ru thin films of two different thicknesses, 100 Å and 1000 Å, over a fluence range of ~1014 to 1017 ions/cm2. The main objective of this study is to investigate the evolution of the structural and wettability properties of Ru thin films of different thicknesses under increasing ion fluence. Overall, the results reveal that increasing ion fluence promotes surface roughening in both film thicknesses, which is correlated with an increase in contact angle. This indicates a clear transition from hydrophilic to hydrophobic behaviour, with the highest contact angle of ~95.54{\deg} observed at a fluence of 1017 ions/cm2. TRIM simulations reveal that for the 100 Å film, the projected ion range exceeds the film thickness, allowing interaction with the bottom substrate, whereas in the 1000 Å film, ion penetration remains largely confined within the Ru layer. GIXRD confirms fluence-dependent structural modification, including peak broadening with preferred orientation changes from Ru (101) to (002). Overall, this study demonstrates that N+-ion irradiation serves as an effective route for tuning both the surface morphology and wettability of Ru thin films, enabling controlled enhancement of hydrophobicity.

Ultrafast creation and manipulation of topologically non-trivial spin objects promises significant potential for spintronic applications. Here, we demonstrate laser-induced nucleation of skyrmions and antiskyrmions with topological charge up to $|Q|=3$ from the saturated magnetization state of a Co/Ni-multilayer which does not intrinsically host a skyrmionic ground state. The resulting configuration of spin objects thus constitutes a metastable, thermodynamically hidden magnetic state. We control the number and type of spin objects by the excitation fluence and the external out-of-plane magnetic field.

In this work, we investigate the nature of gravitational instability of small-scale perturbation modes during the early nonstationary stages of the evolution of disk-like galaxies. To this end, we study the gravitational instability of small-scale horizontal perturbation modes, such as $(m;N) = (12;20)$, $(14;20)$, $(16;20)$, and $(18;20)$, in the framework of a nonlinear nonstationary anisotropic model of a self-gravitating disk. The corresponding nonstationary analogues of the dispersion equation for these perturbation modes are derived, and their numerical analysis is performed. The results are presented in the form of critical dependences of the initial virial ratio on the disk rotation parameter. The nature of the instability of small-scale perturbation modes in a nonlinear nonstationary self-gravitating disk is determined, and a comparative analysis of their instability increments is carried out.

We introduce an on-lattice minimal model of two-dimensional melting, a clock model with vacancies with control parameters temperature, chemical potential and external field. We study the full phase diagram using cluster Monte Carlo, Tensor Network Renormalisation Group and selfconsistent mean field methods. A non-universal ensemble of melting scenarios is observed including the KTHNY scenario of two Berezinskii-Kosterlitz-Thouless phase transitions delimiting a quasilong-range ordered phase. The upper transition evolves into first-order transition in analogy with simulations on hard and soft discs and at low chemical potential there is a single transition between ordered high density and disordered low density phases. The evolution is via a special tricritical point that is accessed in detail. This work therefore provides a framework for understanding the crossover between 2D melting scenarios and offers insights into the behavior of realistic systems.

Signatures of a material object's broken inversion symmetry within its intrinsic excitations and associated optical fields have largely evaded characterization from a perspective that evenly accounts for the inseparability between matter and field dynamics. Here, we formulate a complex-valued pseudoscalar chirality metric that is derived from the coupled electromagnetic and material governing equations, and demonstrate its resolution of the excitational chirality exhibited by the eigenmodes and eigenfields of a family of structurally chiral objects, including those with chirally connected enantiomeric states.

Error detection can suppress noise at a lower sampling cost than probabilistic error cancellation (PEC), but leaves residual logical errors. We combine the two approaches to mitigate these errors while lowering the cost of PEC. We introduce a spacetime Pauli-Lindblad representation and use it to construct the post-selected logical noise perturbatively from physical noise and syndrome information. Individually undetected faults contribute at first order, while detected faults with canceling syndromes generate higher-order terms coupling distinct spacetime locations. To reconcile the nonlinearity of post-selection with the linearity of PEC, we formulate the combined protocol in terms of unnormalized post-selected maps, with normalization performed only after averaging. On the ibm_aachen superconducting quantum processor, Clifford experiments validate the post-selected noise model and its perturbative scaling. We then demonstrate error detection with first-order PEC for transverse-field Ising dynamics using 22 data and 27 check qubits. The combined protocol recovers the mean magnetization within statistical uncertainty through six Trotter steps and reduces the inferred sampling overhead by up to a factor of 63 relative to PEC without post-selection.

The orbiter of the Chandrayaan-3 mission of the Indian Space Research Organisation (ISRO) carries an experimental payload called SHAPE (Spectro-polarimetry of HAbitable Planet Earth). This payload makes disc-integrated observations of Earth as an exoplanet, from the Moon as well as from the high altitude Earth orbit. The instrument consists of an Acousto-Optic Tunable Filter (AOTF) based near-infrared spectro-polarimeter making the measurements in the two orthogonally polarized directions using a pair of Indium-Gallium-Arsenide (InGaAs) detectors. The laboratory characterization of the flight model of the instrument included a relative measurement of the response of the two channels of the instrument. The field measurements of the instrument revealed a non-uniformity in the field response. In the light of non-identical response of the two channels and the non-uniformity of the field response, a theoretical model of such a polarimeter is developed to gain insights into the performance of a polarimeter. Analysis of lunar observations obtained within the SHAPE field of view indicates that the transmission ratio between the two polarized channels lies in the range 0.8-1.2. Such deviations from unity can introduce offsets in the measured polarization of up to about 10%. The suitability of SHAPE for studying the band polarization, defined as the relative polarization within a spectral absorption band, is studied. Using the Moon observations and the theoretical instrumental model, the suitability of measuring the relative band polarization is demonstrated. A study of systematic biases in the band polarization demonstrates a maximum offset of less than 1% in the measured value of the band polarization. The initial results of Earth observations, spectra and flux measurements across phase angles, and the methodology for retrieving the band polarization from these observations are also discussed.

Magic, or nonstabilizerness, is the resource that promotes stabilizer operations to universal quantum computation. For bipartite pure states, its component intrinsic to the correlations between the subsystems, the nonlocal magic, is obtained by minimizing a magic measure over local unitaries. For the stabilizer Rényi entropy (SRE), the minimum is conjectured to be attained by the computational-basis (CB) representative, the state obtained by assigning the Schmidt coefficients in decreasing order to matching computational-basis labels. We prove this conjecture for two families of states at every system size and bipartition: states with dyadic-staircase Schmidt spectra and states of Schmidt rank at most six. For arbitrary bipartite pure states, we show that the CB value exceeds the nonlocal SRE by at most $4$, fixing the leading term of any divergent scaling of nonlocal SRE. We further show that the nonlocal SRE grows at most logarithmically with the entanglement entropy. Consequently, one-dimensional area-law states have bounded nonlocal SRE, while critical states with logarithmic entanglement entropy permit at most doubly logarithmic growth with system size. We apply these results to the transverse-field Ising chain, where we tightly bound the nonlocal SRE in the gapped phases and identify its double-logarithmic growth at criticality.

We investigate the thermodynamic and topological phase structure of charged AdS black holes with a nonminimal gauge–curvature coupling in the grand canonical ensemble. In the minimal-coupling limit $\epsilon=0$, the system exhibits only Hawking–Page-like behavior and does not possess van der Waals criticality. Working perturbatively in the nonminimal coupling, we find that the $\epsilon\neq0$ interaction generates a rich phase structure as the electric potential is varied, including several distinct regimes of critical behavior, a double-critical region, and a regime where conventional criticality disappears. We complement the conventional thermodynamic analysis with a topological description based on the winding number of the thermodynamic vector field. The resulting $r_h$–$\tau$ diagrams reveal that the ordering and morphology of the black-hole branches depend sensitively on both the pressure and the off-shell inverse temperature, with monotonic, disconnected, S-shaped, and cusp-like structures appearing in different parameter ranges. Remarkably, these substantial rearrangements of the solution branches can occur without changing the global winding number. In particular, the system remains in the $W=+1$ topological class beyond the range of conventional criticality, before eventually entering a $W=0$ sector. Our results demonstrate that thermodynamic topology provides complementary global information that is not captured by conventional local criticality criteria alone.

The solution of nonlinear partial differential equations constitutes an important application domain for variational quantum algorithms (VQAs). In this work, we extend the application of VQAs to plasma physics by solving the two-dimensional Grad-Shafranov equation, which describes the equilibrium state of a plasma fluid within the framework of ideal magnetohydrodynamics. For this problem, we develop and investigate two distinct cost function formulations and compare their performance in terms of solution fidelity, convergence speed and quantum resource requirements. Our results, obtained from noiseless simulations, show that the choice of cost function formulation significantly affects the performance of the variational algorithm. The Weak and Picard formulations exhibit complementary characteristics: the former consistently converges faster, whereas the latter achieves slightly lower final infidelities. Exploiting these complementary properties, we introduce a hybrid optimization strategy that combines the rapid initial convergence of the Weak formulation with the higher final accuracy of the Picard formulation. In addition, the two approaches display different quantum resource requirements due to their distinct implementations of boundary conditions. These results highlight the importance of cost function design in the development of efficient VQAs for nonlinear partial differential equations.

We investigate the interference of a heavy radion with the QCD continuum in top-quark-pair production at the High-Luminosity Large Hadron Collider, restricting the numerical study to the pure-radion limit $\xi=0$. The gluon-fusion amplitude combines the QCD trace anomaly with the exact finite-top-mass loop form factor, whose coherent sum fixes both the magnitude and the phase of the production coefficient. Above the top threshold the loop develops an absorptive part, rendering the production coefficient complex and allowing the interference to remain non-zero on the resonance pole, where a purely real point-like coefficient would give none. The complex coefficient is validated independently using a native loop-induced implementation and a common-event phase-basis construction. The resulting signature is a peak–dip deformation rather than a positive bump, while detector smearing turns the narrow truth-level structure into a broad sub-percent distortion. For $3\,\mathrm{ab}^{-1}$ at $\sqrt{s}=14$ TeV, we construct an ATLAS-anchored phenomenological response and perform an exact binned Poisson Asimov analysis with a free background normalization and a correlated shape nuisance. For a $0.1\%$ shape benchmark with a $50$ GeV correlation length, the profiled median $95\%$ $CL_s$ reach in $\Lambda_r$ is $2.49$, $2.82$, $3.00$, $2.56$, and $2.19$ TeV for radion masses of $600$, $800$, $1000$, $1200$, and $1500$ GeV, respectively. A diagnostic decomposition at $800$ GeV gives $2.18$ TeV for the resonance-squared term alone and $2.83$ TeV for the interference term alone. A selected-background deformation stress test largely removes the apparent maximum near $1$ TeV, showing that its location and prominence are normalization-prescription dependent, while leaving the central conclusion unchanged: the projected sensitivity is predominantly interference driven.

We present a unified frozen natural orbital (FNO) framework for periodic Gaussian-orbital post-Hartree-Fock calculations with explicit k-point sampling. The approach includes conventional ground-state FNOs together with state-specific (SS-FNO) and state-averaged (SA-FNO) variants constructed from perturbative one-particle density matrices. We implement these approximations for periodic Moller-Plesset perturbation theory, algebraic diagrammatic construction, and equation-of-motion coupled cluster methods in the PySCF software package and benchmark them for correlation energies, equations of state, fundamental band gaps, and quasiparticle band structures of semiconductors and insulators. FNO truncation reproduces canonical results with small errors while substantially reducing computational cost. SS-FNO enables accurate large-basis band-gap calculations, including quadruple-zeta results, whereas SA-FNO efficiently compresses the virtual space for multi-state band-structure calculations. Combined with basis-set and thermodynamic-limit extrapolations, the framework provides a practical route to high-accuracy correlated calculations in periodic systems.

Fault-tolerant quantum programs thread together reusable logical operations, yet correcting errors requires comparing measurements across operation boundaries. Correlations tie each operation's error analysis to the computation around it. Adaptive computation makes this a runtime challenge: measurement results determine which operation comes next, so the error analysis must keep pace with execution. We introduce extended detector error models (EDEMs), which compose in sequence and in parallel, mirroring the composition of physical realizations and their detector contracts. We prove how detectors, the measurement parities used to diagnose errors, can be split across circuit boundaries, and establish conditions under which composition recovers the assembled circuit's detector error model. This structure supports symbolic precompilation and analysis of entire families of circuits. It also defines error models for decoding windows and the boundary information through which committed corrections affect subsequent windows. The same interface thus connects the design of individual logical operations to the decoding of an unfolding quantum program.

We experimentally demonstrate second- and third-order exceptional bound states in the continuum (EP-BICs), formed by the merging of two and three symmetry-protected BICs at an exceptional point (EP). Our passive reciprocal acoustic platform consists of symmetry-protected BIC cavities coupled through an acoustic waveguide and enables independent control of intrinsic loss, radiative loss, and near-field coupling between the cavities. A nonuniformly distributed intrinsic loss provides the non-Hermiticity required for EP formation while preserving decoupling from the waveguide radiation channel. The EP-BICs are probed using both near- and far-field excitation. In the near field, local intracavity excitation directly accesses the symmetry-protected BICs and reveals their spectral evolution. For far-field excitation, we intentionally break the protecting geometrical symmetry, converting the BICs into quasi-BICs and making them accessible through transmission measurements. Extending the system to three cavities with graded intrinsic loss realizes a third-order EP-BIC and yields a larger spectral response to the implemented coupling perturbation. These results establish a passive reciprocal route to higher-order exceptional degeneracies with independent control over intrinsic loss, near-field coupling, and radiative access.

The ability to controllably manipulate non-Hermitian wave scattering environments has been used to discover exotic scattering phenomena such as scattering exceptional points and coherent perfect absorption, and create numerous applications including signal routing, filtering, imaging, sensing, wireless power transfer, etc. We introduce the concept that many of these applications and phenomena are fundamentally governed by singularities of the scattering matrix. With this understanding, our demonstrated ability to control the location of scattering singularities can be used to enhance current applications and develop new ones. In generic complex scattering systems, there is an abundance of topologically protected scattering singularities corresponding to complex zeros of various functions of the scattering matrix. We show that with just three tunable parameters we are able to create the conditions for nearly any scattering singularity at arbitrary frequencies in such systems. With five tunable parameters, we demonstrate that more complex scenarios can be accomplished, such as making disparate singularities coincident or placing singularities at different frequencies. A benefit of systems with tunable parameters is that generic complex systems can be re-purposed into exhibiting many different useful properties solely by reconfiguring their tunable parameters. A particularly interesting scattering phenomenon is coherent perfect absorption, where a specific wavefront injected into the system is completely absorbed, with no energy reflected or transmitted through any channel. After creating the conditions for this singularity at an arbitrary preselected frequency, we can find and inject the coherent perfect absorption wavefront and demonstrate output-to-input power ratios as low as 1x10^{-10}, 2x10^{-8}, and 3x10^{-8} in a quarter bowtie billiard with two, three, and four ports, respectively.

We study dimension-free Bohnenblust–Hille inequalities for local operators on systems of $K$-level qudits. For the operator space of support at most $d$, uniformly over all tensor-product orthonormal operator bases, we prove a Bohnenblust–Hille inequality with the optimal exponent $2d/(d+1)$ whose asymptotic exponential base in the interaction order is of order $O(\sqrt K)$. Our proof is intrinsic, based on a one-site scalarization and block-transversal decoupling, and does not rely on a scalarization to the cyclic group or on a Remez-type argument. We complement the upper bound by showing that the asymptotic exponential Bohnenblust–Hille base satisfies $cK^{1/4}\le \beta(K)\le C\sqrt K$ with universal constants $c,C>0$. In this sense, the present work may be viewed as continuing the line of work of Slote–Volberg–Zhang from a complementary intrinsic viewpoint. We also revisit their Gell–Mann and Heisenberg–Weyl scalarization procedures. In the Heisenberg–Weyl setting, the prime-dimensional case already yields the optimal interaction exponent, whereas for composite $K$ the scalar total degree used in their reduction leads to a larger exponent. A support-sensitive formulation recovers the optimal interaction exponent for every $K$, while the intrinsic argument gives the stronger dependence on the local dimension at the level of the asymptotic exponential base. As further consequences, we determine the sharp scale, up to factors exponential in $d$ with base depending only on $K$, of coefficient $\ell_1$-normalization and unconditionality on the exact-support spaces. This yields dimension-free coefficient sparsification, including sparse generalized-Pauli approximation in Heisenberg–Weyl coordinates, as well as normalization and query bounds for canonical LCU/qubitization constructions.

Becker et al. produced a striking trace formula for the sum of fourth powers of generalized magic angles, $ \theta $, for the chiral model of twisted bilayer graphene (TBG) with the exact Bistritzer–MacDonald potential: $\sum \theta^{4} = 8 \pi / \sqrt 3 $. The purpose of this note is to generalize this formula to a larger class of potentials satisfying the symmetries of the model.

The cubic phase gate is the only non-Gaussian element of universal continuous-variable quantum computation. Its Fock amplitudes are known in closed form only when the input is a Fock state. For a Gaussian input the usual route is to build the cubic quadrature in a truncated Fock space and exponentiate it, which alters the generator before the exponential is taken. A closed form is obtained here for every pure single-mode Gaussian input, with the squeezing along any quadrature axis and with arbitrary displacement and boost. It is a finite combination of the Airy function and its derivative, and the argument is shared by all Fock indices, so a whole Fock profile costs two Airy evaluations. A recurrence is also derived that builds each coefficient from the four preceding ones, together with the regime in which it is stable. Evaluating the closed form at the weak nonlinearities of current experiments requires care, since its terms grow large and alternate in sign. The precision this demands is quantified, and the truncated construction is benchmarked against the exact result, whose error at cutoffs in common use is found to be of the same size as the quantity being computed.

An absolutely entangled set (AES) is a collection of states for which at least one member remains entangled under any choice of global unitary transformation. We develop a semi-device-independent framework for certifying this property from dimensionally bounded prepare-and-measure correlations. A witness value above the maximum attainable with separable preparations of a given dimension rules out every non-AES realization. To upperbound this limit, we construct a semidefinite-programming (SDP) hierarchy tailored to separable preparations. For a two-qubit random-access-code witness, the SDP upper bound and the heuristic lower bound coincide to the reported precision, yielding a concrete AES certification. We also formulate a general construction of witnesses for extended preparation sets containing target pure-state AESs. Examples based on equiangular tight frames, a minimal AES, and mutually unbiased bases further illustrate the scope of the method. In summary, our results establish a systematic and experimentally feasible approach to the certification of AESs in semi-device-independent quantum information protocols.

Recently, unconventional superconductivity hosted by twisted van der Waals (vdW) heterostructures has received immense interest due to the exotic pairing symmetry, electronic interactions and nontrivial topological nature that are naturally relevant to the fast-advancing quantum technologies. Here, we report scanning-probe quantum sensing of nanoscale electromagnetic behaviors of twisted vdW cuprate superconductors. Using single-spin relaxometry, we directly visualize edge modes spontaneously formed in twisted Bi2Sr2CaCu2O8+x (BSCCO). By investigating temperature dependent variations of edge-state-induced quantum spin relaxation, we experimentally evaluate the magnitude of nontrivial topological band gap opened at nodal points in twisted BSCCO and its critical temperature behaviors under different twist angles. We further observe alternating chiral domains defined by edge modes, exploring experimental signatures of in-plane magnetic field-induced topology in 45{\deg} twisted BSCCO. Our results advance the current understanding of twisted vdW nodal superconductors, presenting an appealing high-temperature topological superconducting material platform for cutting-edge quantum innovation.

Recently, we have shown that the hypothesis of the dark-matter (DM) origin of the Belle II excess events in $B\to K M_X$ decays allows for a successful description of the data. The DM parameters (masses and couplings) in two DM scenarios with either scalar (S-scenario) or vector (V-scenario) mediator have been extracted with rather small uncertainty from fits to the $B\to K M_X$ data. The same mechanism leads to a similar enhancement of the $B_s\to (\eta,\eta',\phi) M_X$ decay rates. We present a detailed analysis of $B\to K^* M_X$ and $B_s\to \phi M_X$ decays and show that these decays provide a clear probe of the S- and V-scenarios: Compared to the Standard Model, in the S-scenario an enhancement by a factor $\sim 1.6$ is expected, whereas the V-scenario leads to a much larger enhancement by a factor $\sim 3.5$. For the $B\to K^* M_X$ decays, we provide the expected number of events at Belle II for the sample for which a rather large enhancement of $B\to K M_X$ decays compared to the Standard Model expectations has been reported.