We study the high power ferromagnetic resonance of perpendicularly magnetized BiYIG nanodisks where the uniaxial anisotropy almost compensates for the shape anisotropy. We observe a strong saturation of the averaged magnetization upon moderately increasing the amplitude of the rf field and a broadening of the ferromagnetic resonance line toward lower and higher magnetic fields. Full micromagnetic simulations reveal that a self-modulation of the dynamic magnetization is responsible for this behavior. To get more insight into this unstable dynamics, we analyze it in terms of normal modes. The number of modes involved is found to rapidly increase above the critical threshold. Still, a normal mode model taking into account only a few of them and their mutual nonlinear couplings allows us to reproduce the observed phenomenon. The normal mode analysis and micromagnetic simulations also predict a Suhl-like instability at a larger excitation power, when it is slowly increased from low values, and bistability. Using two-tone spectroscopy, we directly measure the self-modulation spectrum and provide experimental evidence of bistable dynamics. These findings open some perspectives on using high dimensional dynamics in magnetic nanostructures for unconventional information processing.

The control of unconventional magnetism, which displays ferromagnetismlike properties with compensated magnetization, has drawn intense attention for advancing antiferromagnetic spintronics. Here, through symmetry analysis, we propose a general stacking rule, characterized by a connection operator linking two stacked bilayers, for controlling unconventional magnetism via sliding ferroelectricity. Such a rule enables the simultaneous switching of both electric polarization and nonrelativistic spin splitting or anomalous Hall effect in altermagnets, a class of collinear unconventional magnets. By comprehensively surveying the 80 layer groups, we identify all the stacking orders that allow for such two types of simultaneous switching. Furthermore, we extend the stacking rule to collinear compensated ferrimagnets, where the opposite-spin sublattices are not connected by any symmetry operator, yet the net magnetization remains zero. Combined with first-principles calculations, we demonstrate the sliding ferroelectric control of spin polarization and anomalous Hall effect in the altermagnetic ${\mathrm{AgF}}_2$ and ${\mathrm{Fe}}_2{\mathrm{MoSe}}_4$ bilayers. Our Letter provides a symmetry strategy for achieving ferroelectric control of unconventional magnetism in bilayer systems and opens avenues for exploring new types of magnetoelectric coupling.

Overdamped stochastic systems maintained far from equilibrium can display sustained oscillations with fluctuations that decrease with the system size. The correlation time of such noisy limit cycles expressed in units of the cycle period is upper-bounded by the entropy produced per oscillation. We prove this constraint for first-order nonlinear systems in arbitrary dimensions perturbed by weak, uncorrelated Gaussian noise. We then extend the result to important examples of more general stochastic dynamics, including electronic and chemical clocks, illustrating the practical relevance of the dissipation-coherence bound for electronic computing and thermodynamic inference.

We revisit the measurement-induced phase transition (MPT) in Clifford circuits, which are both classically simulable and exhibit critical behavior widely believed to be distinct from classical percolation theory, using ZX calculus. We analyze the MPT in a dynamical model composed of controlled not (cnot) gates, SWAP gates, identity gates, and Bell-pair measurements, respectively, arranged randomly in a brickwork pattern. Our circuits exhibit a transition that is seemingly distinct from classical percolation based on standard arguments, that is in line with the prevailing understanding in the field. In contrast, by employing ZX-calculus based simplification techniques, we unveil a hidden percolation transition within the circuit structure. We demonstrate that the classical percolation transition in the ZX-simplified network coincides with the MPT observed through mutual information. Our findings suggest that the MPT in Clifford circuits is, in fact, controlled by a classical percolation transition in disguise.

Superconducting qubit systems, one of the leading candidates for universal quantum computing, face scalability challenges such as frequency crowding, wiring complexity, and packaging problems. Distributed quantum computing offers a viable strategy for constructing larger quantum information processing systems. Yet, direct universal quantum gates between remote qubits—critical to distributed architectures—remain unrealized. Here, we demonstrate direct high-fidelity entangling gates between two remote superconducting quantum processors separated by a 30 cm distance, utilizing standing-wave modes in their connecting coaxial cable. We achieve cross-entropy benchmarking fidelities of $(99.15\pm 0.02)\%$ and $(98.03\pm 0.04)\%$ for the controlled-not and controlled-z gates, respectively, outperforming state transfer and feedback-based protocols in fidelity and efficiency. This advancement significantly enhances the prospect of universal distributed quantum information processing, which is the critical step toward future large-scale quantum systems.

We introduce a new method for the study of fluctuations of partial transition widths based on nuclear resonance fluorescence experiments with quasimonochromatic linearly polarized photon beams below particle separation thresholds. It is based on the average branching of decays of $J=1$ states of an even-even nucleus to the $2_1^{+}$ state in comparison to the ground state. Between 5 and 7 MeV, a constant average branching ratio for $\gamma$ decays from $1^{-}$ states of 0.490(16) is observed for the nuclide ${}^{150}\mathrm{Nd}$. Assuming ${\chi }^2$-distributed partial transition widths, this average branching ratio is related to a degree of freedom of $\nu =1.93(12)$, rejecting the validity of the Porter-Thomas distribution, requiring $\nu =1$. The observed deviation can be explained by nonstatistical effects in the $\gamma$-decay behavior with contributions in the range of 9.4(10)% up to 94(10)%.

Highly charged cations are omnipresent species after the interaction of high-energy or high-intensity light with matter. When embedded in environments, the mechanism and outcome of the redistribution of the cation’s charge are crucial for the further fate of the whole system. Generally, ground-state cations can decay by charge transfer, proceeding radiatively, through nuclear dynamics, or by electron-transfer-mediated decay (ETMD). ETMD causes electron emission from a remote neighbor and appears ubiquitous in loosely bound systems. It remained unclear how multiply charged ions decay if conventional ETMD channels are closed. Here, we show that a yet undiscovered variant of ETMD is possible, where multiple electrons are collectively transferred. Explicitly, we observe ETMD in which two electrons from two distinct neighbors (partially) neutralize a multiply charged ion, and an electron from a fourth site is emitted. According to the established nomenclature, we suggest naming the process ETMD(4).

Waveguides offer a means to controllably couple atomic ensembles to the electromagnetic field therein. Here, we demonstrate x-ray propagation in planar thin-film waveguides coupled to Mössbauer nuclei under collective resonant excitation by short pulses of synchrotron radiation. We record x-ray photons that have been emitted into resonant modes of the waveguide. Depending on the geometry and mode of excitation, two fundamentally different signatures of the collective emission are observed, for which we present a unifying theoretical model. Our results form a new platform for waveguide quantum electrodynamics in the hard x-ray regime with the potential to provide a coherent narrow band source of x-rays on the nanometer scale.

We investigate the majorization order for comparing wave coherence and reveal its fundamental consequences in transport measurements, including power distribution, absorption, transmission, and reflection. We prove that all these measurements preserve the majorization order under unitary control, enabling direct experimental characterization of the majorization order. Specifically, waves with lower coherence in the majorization order exhibit more restricted ranges of achievable measurement values. Our results deepen the understanding of coherence in transport phenomena.

We demonstrate, both theoretically and experimentally, that arbitrary scatterers preserving parity–time-reversal–duality ($\mathcal{P}·\mathcal{T}·\mathcal{D}$) symmetry inherently produce a backscattered wave whose electric field is the mirror-symmetric counterpart of the incident electric field, up to an amplitude factor, with respect to the system’s characteristic mirror plane. Specifically, we establish that a general elliptically polarized wave, when reflected from such structures, exhibits a polarization state related to the polarization ellipse of the incident wave by a parity transformation. Notably, a circularly polarized wave reflects with spin angular momentum opposite to that of the incident field, in stark contrast to reflection from conventional conducting objects. These findings enable several applications such as reflective polarizers and spin-selective devices.

We show that activity and broken fore-aft shape symmetry enable microswimmers to cross streamlines in nonuniform shear, a key yet overlooked factor in active cross-stream migration. Using a model of flagellated microswimmers in microchannel flow, we find that hydrodynamic coupling and flagellar flexibility significantly impact migration. A simplified theory identifies key factors driving the underlying rich nonlinear dynamics. Our findings apply to dynamics and control of both living and artificial microswimmers, while the hydrodynamic framework extends to diverse shear flow scenarios.

Magnetic flux ropes, fundamental magnetohydrodynamic structures, often form braided helical configurations with net axial current, as observed in astrophysical and laboratory plasmas. However, an equilibrium model for such structures has remained elusive. We present a first-principles derivation of the braided flux ropes equilibrium by capturing the force balance of current-carrying plasma strands. This equilibrium reproduces the observed structure of the double helix nebula and provides a powerful tool for studying magnetic self-organization, plasma confinement, and astrophysical dynamics.

We investigate the spatially resolved dynamics of the collective amplitude Schmid-Higgs (SH) mode in disordered $s$-wave superconductors and fermionic superfluids. By analyzing the analytic structure of the zero-temperature SH susceptibility in the complex frequency plane, we find that, when the coherence length greatly exceeds the mean free path, (i) the SH response at fixed wave vectors exhibits late-time oscillations decaying as $1/t^2$ with frequency $2\mathrm{\Delta }$, where $\mathrm{\Delta }$ is the superconducting gap; (ii) subdiffusive oscillations with a dynamical exponent $z=4$ emerge at late times and large distances; and (iii) spatial oscillations at a fixed frequency decay exponentially, with a period that diverges as the frequency approaches $2\mathrm{\Delta }$ from above. When the coherence length is comparable to the mean free path, additional exponentially decaying oscillations at fixed wave vectors appear with a frequency above $2\mathrm{\Delta }$. Furthermore, we show that the SH mode induces an extra peak in the third-harmonic generation current at finite wave vectors. The frequency of this peak is shifted from the conventional resonance at $\mathrm{\Delta }$, thereby providing an unambiguous signature of order parameter amplitude dynamics.

Relying on the anharmonic special displacement method, we introduce an ab initio quasistatic polymorphous framework to describe local disorder, anharmonicity, and electron-phonon coupling in superionic conductors. Using cubic ${\mathrm{Cu}}_2\mathrm{Se}$, we show that positional polymorphism yields the breakdown of the phonon quasiparticle picture, leading to extremely overdamped anharmonic vibrations while preserving transverse acoustic phonons, consistent with experiments. We also demonstrate highly broadened electronic spectral functions with band gap openings of 1.0 eV due to polymorphism, and that anharmonic electron-phonon coupling leads to a band gap narrowing with increasing temperature. Our approach, relying on generating a handful of configurations, opens the way for efficient calculations in superionic crystals to elucidate their compelling high figure of merit.

As a hallmark of the quantum Hall effect, chiral edge modes (CEMs) counterpropagate along the two parallel edges of a ribbon structure. However, recent studies demonstrate counterintuitive anti-CEMs that copropagate along the parallel edges. Analogous to the established extension of the CEMs to helical edge modes (HEMs) in the quantum spin Hall effect, it is natural to extend the anti-CEMs to anti-HEMs, which comprise a pair of time-reversal-related anti-CEMs. In this Letter, we report the first observation of the anti-HEMs based on a bilayer model that features staggered positive and negative interlayer hoppings. Experimentally, we implement this antihelical model on an acoustic platform and provide compelling evidence for the anti-HEMs by selectively exciting different spin subspaces, along with identifying the energy-biased Dirac points in bulk spectra. Our findings may offer new insights into topological phases of matter and potentially pave the way for designing novel devices with unique edge transport properties.