Many swimming microorganisms navigate their environment by modulating the curvature of their swimming trajectories in response to external cues. Here, we show that the biflagellate alga Chlamydomonas reinhardtii swims in circles and actively switches its trajectory handedness in response to orthogonal illumination: the cell swims counterclockwise at low light intensities yet clockwise at high light intensities. This handedness switching arises from light-dependent modulation of flagellar beating, including rapid and reversible changes in beat extension, phase, and—crucially—beat plane orientation. Using high-speed imaging and hydrodynamic modeling, we reveal that this beat plane reorientation is critical for Chlamydomonas to swim orthogonally to light as well as to dynamically modulate its trajectory curvature, enabling transitions between global exploration and localized searching in spatially structured light fields. Our results establish beat plane reorientation as a novel mechanism for curvature control in microswimmer navigation.

A power ramp from L- to H-mode-like conditions is carried out in a 50 ms long global full-$f$ turbulence simulation of ASDEX Upgrade with the grillix code. After 32 ms of slow profile evolution, a sudden change in transport triggers a pedestal buildup within $\sim 100\mathrm{\mu }\mathrm{s}$. This transition results from an abrupt shift from drift-wave (DW) to kinetic-ballooning-mode (KBM) turbulence. The self-consistently evolved $E\times B$ flow shear first increases slowly and then sharply. Geodesic acoustic mode and Alfvénic flow oscillations intensify prior to the transition and subsequently die out. This is followed by slow oscillations of the transport and profiles, reminiscent of a dithering I-phase or edge-localized-mode (ELM) cycles observed experimentally. This study paves the way for a better understanding of confinement regime transitions.

We report ultrahigh magnetic field Faraday rotation results on the chiral helimagnet ${\mathrm{Cu}}_2{\mathrm{OSeO}}_3$, the first Mott insulator showing skyrmion lattice phases and a linear magnetoelectric effect. Between 180 and 300 T, we find signatures of a Bose-Einstein condensation of magnons, which can be described as a canted XY ferrimagnet. Because of the magnetoelectric coupling, the transverse magnetic order of the individual ${\mathrm{Cu}}^{2+}$ spins is accompanied by a characteristic domelike electric polarization which is crucial for the observation of the condensate via the Faraday rotation effect.

Gravitational waves emitted in the late inspiral of binary neutron stars are affected by their tidal deformation. We study the tidal dynamics in full general relativity through matched-asymptotic expansions and show that the dynamical tidal response can be expanded in a set of modes. We further show that the mode amplitudes satisfy an effective, forced harmonic oscillator equation, which generalizes the overlap-integral formulation of Newtonian gravity. Our relativistic treatment of dynamical tides will avoid systematic biases in future gravitational-wave parameter estimation and can be generalized to model nonlinear tidal interactions and include the presence of elastic, electromagnetic, or dark matter field interactions with nuclear matter.

We report a search for exotic spin-spin interactions between neutrons and electrons which could signal new physics beyond the standard model using slow neutron polarimetric imaging through a dense medium of polarized electrons. Our dense polarized electron target is a ferrimagnet held at its magnetic compensation temperature, which realizes a polarized electron ensemble with zero net magnetization. We sought the spin rotation of transversely polarized neutrons from a neutron-spin–electron-spin interaction of the form $V_2=-g_A^e{g}_A^n(\hslash c/4\pi ){\overrightarrow{\sigma }}_e·{\overrightarrow{\sigma }}_n(e^{-r/{\lambda }_c}/r)$, where $g_A^e$ and $g_A^n$ are the electron and neutron axial couplings, $\overrightarrow{{\sigma }_e}$ and $\overrightarrow{{\sigma }_n}$ are the electron and neutron spin, and ${\lambda }_c$ is the interaction range for an exotic axial vector interaction from massive spin-1 boson exchange of mass $\hslash c/{\lambda }_c$. The resulting average neutron-spin-rotation angle per unit length, $(d{\overline{\varphi }}_{F5}/dz)=[0.41\pm 6.3(\mathrm{stat})\pm 4.4(\mathrm{sys})]\times {10}^{-3}\mathrm{rad}/\mathrm{m}$, is consistent with zero. Our novel approach improves the previous upper limits on the coupling constant product $g_A^e{g}_A^n$ by several orders of magnitude in the poorly explored ${10}^{-8}\le {\lambda }_c\le {10}^{-2}\mathrm{m}$ range.

Polarized single-photon sources (SPSs) are valuable for quantum information applications and can be implemented by exploiting an elliptical or birefringent cavity that provide polarization-selective Purcell enhancement. However, current designs suffer from similar quality ($Q$) factors of split cavity modes, requiring both high Purcell factor and substantial mode splitting for ideal polarization performance. Here, we report a low-Purcell anisotropic Dirac cavity that supports orthogonally polarized modes with significantly distinct $Q$ factors (1032 vs 98). When coupled to a single quantum dot, this cavity enables single-photon emission [$g^{(2)}(0)=0.028$] with $>99\%$ degree of linear polarization (DoLP). The high DoLP is tolerant to emission wavelength, originating from suppression of competing radiative channels. Lifetime measurements demonstrate a 1.72-fold enhancement at cavity resonance and a 3.47-fold inhibition in a photonic band gap. Additionally, the anisotropic Dirac cavity exhibits vertical directionality with simulated collection efficiency up to 92.7%. Our results offer a novel strategy toward ideal solid-state polarized SPSs.

Achieving high-fidelity qubit readout and reset while maintaining qubit coherence is crucial for quantum error correction and advanced quantum algorithms. Here, we design and experimentally demonstrate a scalable architecture based on frequency-tunable nonlinear Purcell filters, which enables flexible readout and rapid unconditional reset of multiple superconducting qubits. Our readout protocol dynamically adjusts the effective linewidth of the readout resonator through a tunable Purcell filter, optimizing the signal-to-noise ratio during measurement while suppressing photon noise during idle periods. Combined with a multilevel readout protocol, we achieve the highest readout fidelity of 99.3% without any quantum-limited amplifier, even with a small dispersive shift. Moreover, by leveraging a reset channel formed via the adjacent coupling between the filter and the coupler, we realize unconditional qubit reset of both leakage-induced $|2⟩$ and $|1⟩$ states within 200 ns and reset of the $|1⟩$ state alone within 75 ns, with error rates $\le 1\%$. The filter also mitigates both photon-induced dephasing and the Purcell effect, thereby preserving qubit coherence. This scalable Purcell filter architecture shows exceptional performance in qubit readout, reset, and protection, marking it as a promising hardware component for advancing fault-tolerant quantum computing systems.

Entangled states hold the promise of improving the precision and accuracy of quantum sensors. We experimentally demonstrate that spectroscopy of an optical clock transition using entangled states can outperform its classical counterpart. Two ${{}^{40}\mathrm{Ca}}^{+}$ ions are entangled in a quantum state with vanishing first-order magnetic field sensitivity, extending the coherence time of the atoms and enabling near-lifetime-limited probe times of up to 550 ms. In our protocol, entangled ions reach the same instability as uncorrelated ions, but at half the probe time, enabling faster cycle times of the clock. We run two entangled ${{}^{40}\mathrm{Ca}}^{+}$ ions as an optical clock and compare its frequency instability with a ${}^{87}\mathrm{Sr}$ lattice clock. The instability of the entangled ion clock is below a clock operated with classically correlated states for all probe times. We observe instabilities below the theoretically expected quantum projection noise limit of two uncorrelated ions for interrogation times below 100 ms. The lowest fractional frequency instability of $7\times {10}^{-16}/\sqrt{\tau /1\mathrm{s}}$ is reached for 250 ms probe time, limited by residual phase noise of the probe laser. This represents the lowest instability reported to date for a ${{}^{40}\mathrm{Ca}}^{+}$ ion clock.

Structural superlubricity (SSL) promises nearly frictionless and wearless sliding but has until now been considered a special and extreme interfacial phenomenon limited to micro- and nanoscale contacts. Here, we demonstrate robust macroscale SSL within a single submillimeter graphite contact. Previously reported near-zero friction coefficients, where friction is nearly independent of normal load, have only been observed at microscale contacts under low loads. Our system expands both contact size and load into the macroscopic regime, exhibiting friction coefficients that fluctuate around zero and reach values as low as $\sim {10}^{-6}$ across a broad load range from 1 mN to 0.5 N. Negative friction coefficients are also observed. Similar behavior is observed at graphite$/{\mathrm{MoS}}_2$ interfaces, indicating that macroscale SSL is a generalizable phenomenon across flat layered materials. These findings overturn long-standing scaling limitations and establish macroscale SSL as a paradigm-shifting platform for next-generation mechanical and electromechanical systems.

Monolayers (MLs) of semiconducting transition metal dichalcogenides emit light very efficiently and display rich spin-valley physics, with gyromagnetic ($g$) factors of about $-4$. Here, we investigate how these properties can be tailored by alloying. Magneto-optical spectroscopy is used to reveal the peculiar properties of excitonic complexes in ${\mathrm{Mo}}_x{\mathrm{W}}_{1-x}{\mathrm{Se}}_2$ MLs with different metal concentrations. We show that the alloys feature extremely high $g$ factors for neutral excitons, that change gradually with the composition up to reaching values of the order of $-10$ for $x\approx 0.2$. First-principles calculations quantitatively identify the alloy-induced mixing between different conduction band valleys as the underlying mechanism originating the anomalous composition dependence of the neutral exciton $g$ factor. The theoretical framework also suggests a high strain sensitivity of the alloys, making them promising candidates for tailor-made optoelectronic devices.

We develop a mean-field theory of the stability of fractional Chern insulators based on the dipole picture of composite fermions (CFs). We construct CFs by binding vortices to Bloch electrons and derive a CF single-particle Hamiltonian that describes a Hofstadter problem in the enlarged CF Hilbert space, with the trace-condition term emerging naturally in the small-$q$ limit as part of the CF Hamiltonian. Going beyond the small-$q$ limit, we apply our theory to twisted ${\mathrm{MoTe}}_2$ and calculate its CF band structures. The resulting CF phase diagram matches closely with that from exact diagonalization, and the projected many-body wave functions achieve exceptionally high overlaps with the latter. Our theory provides both a microscopic understanding and a computationally efficient tool for identifying fractional Chern insulators.

We consider unconventional magnets with and without spin-singlet $s$-wave superconductivity and demonstrate the emergence of spin triplet states due to light drives. In particular, we find that a high-frequency linearly polarized light drive induces a spin-triplet density in $d$-wave altermagnets which does not exist in the static regime and can directly reveal the strength of the altermagnetic field. In this high-frequency regime, we also show that linearly polarized light enables the formation of odd-frequency spin-triplet superconducting correlations possessing $d$-wave and $s$-wave parities, which can be controlled by the light drive and accessed by measuring the spin density. Moreover, for low-frequency linearly and circularly polarized light drives, we obtain that the types of superconducting correlations are broadened due to the presence of Floquet bands, enabling spin-triplet pairs in $d$- and $p$-wave unconventional magnets, which are absent in the static phase.

Traveling fronts ubiquitous in physics, chemistry, and biology are prone to transverse cellular deformations due to diffusive or convective instabilities. Here, we show both theoretically and experimentally that new patterns can be obtained if the destabilization is triggered around a front locked radially by advection. Specifically, angularly shifting sun-ray-like patterns can develop around an autocatalytic front frozen by radial advection. These patterns arise from a diffusive instability that occurs when the autocatalyst $X$ and the reactant $Y$ diffuse at different rates. The properties of these shining-star structures can be controlled by tuning the flow rate $Q$ and the ratio of diffusion coefficients $\delta$ as evidenced by linear stability analysis, nonlinear simulations, and experiments on the chlorite-tetrathionate reaction.

Supermassive black hole (SMBH) binary systems are an unavoidable outcome of galaxy mergers. Their dynamics encode valuable information about their formation and growth, the composition of their host galactic nuclei, the evolution of galaxies, and the nature of gravity. Many SMBH binaries with separations pc-kpc have been found, but closer (subparsec) binaries remain to be confirmed. Identifying these systems may elucidate how binaries evolve past the “final parsec” until gravitational radiation drives them to coalescence. Methods to discover and characterize SMBH binaries can shed light on these important questions and potentially open new multimessenger channels. Here we show that SMBH binaries in nonactive galactic nuclei can be identified and characterized by the gravitational lensing of individual bright stars, located behind them in the host galaxy. The rotation of “caustics”—regions where sources are hugely magnified due to the SMBH binary’s orbit and inspiral—leads to quasiperiodic lensing of starlight (QPLS). The extreme lensing magnification of individual bright stars produces a significant variation in the host galaxies’ luminosity; their lightcurve traces the orbit of the SMBH binary and its evolution, analogous to the waveforms recorded by gravitational-wave (GW) detectors. QPLS probes the population of sources observable by pulsar timing arrays and space detectors (LISA, TianQin), offering advance warning triggers for merging SMBHs for coincident or follow-up GW detections. SMBH population models predict 1–50 $[190–5000](n_{\star }/{\mathrm{pc}}^{-3})$ QPLS binaries with period less than 10[40] yr with comparable masses and redshift $z<0.3$, where $n_{\star }$ is the stellar number density. Additionally, stellar and orbital motion will lead to frequent instances of single or double flares caused by SMBHBs with longer periods. This novel signature can be searched for in a wealth of existing and upcoming time-domain photometric data: identifying quasiperiodic variability in galactic lightcurves will reveal an ensemble of binary systems and illuminate outstanding questions around them.

We investigate how material diffusion processes affect the temporal evolution of the radii of DNA droplets formed from DNA nanoparticles whose phase-separation ability can be enzymatically degraded. The droplets are immobilized so as to disallow Brownian coalescence, and their size is tracked using confocal fluorescent microscopy. Without enzymes, we observe very slow Ostwald ripening in rough agreement with the Lifshitz-Slyozov-Wagner theory. With enzymes, we observe a dynamic radius distribution in which time and radius decouple, leading to an unusual behavior in which the average radius remains constant despite the total droplet volume decreasing. Our Letter provides insights into the statistical dynamics of phase-separated droplets, with relevance to both biological condensates and materials applications.

By combining artificial intelligence and fluid physics, we discover a closed-form closure for 2D turbulence from small direct numerical simulation data. Large-eddy simulation with this closure is accurate and stable, reproducing direct numerical simulation statistics, including those of extremes. We also show that the new closure could be derived from a fourth-order truncated Taylor expansion. Prior analytical and artificial-intelligence-based work only found the second-order expansion, which led to unstable large-eddy simulation. The additional terms emerge only when interscale energy transfer is considered alongside standard reconstruction criterion in the sparse-equation discovery.

The construction of cavity quantum electrodynamic systems is pivotal for advancing the development of quantum emitters, yet it is fundamentally constrained by the trade-off between a cavity’s quality factor ($Q$) and its mode volume ($V$) in conventional cavities. This causes a bottleneck for single-photon sources when improving the key performance metrics of brightness, purity, and indistinguishability. Here, we overcome this limitation by invoking nonradiative states in the plasmonic metasurface that decouples $Q$ and $V$. Quasibound states in the continuum regulate electromagnetic field confinement in time ($Q$) while anapole states enable strong electromagnetic field confinement in space ($V$). This independent manipulation over $Q$ and $V$ allows us to separately control Purcell factor and cavity linewidth, leading to concurrent improvements of brightness and indistinguishability. Working at room temperature, single-photon emission from two-dimensional hexagonal boron nitride integrated with the plasmonic metasurface is raised by about 3 orders of magnitude. Furthermore, maximal chiral emission is also demonstrated via coordinated spatiotemporal regulation. Our findings pave the way for practical application of compact quantum emitters, and provide new insights into light-matter interaction.

We demonstrate that the machine learning of density functionals allows one to determine simultaneously the equilibrium chemical potential across simulation datasets of inhomogeneous classical fluids. Minimization of a loss function based on an Euler-Lagrange equation yields both the universal one-body direct correlation functional, which is represented locally by a neural network, as well as the system-specific unknown chemical potential values. The method can serve as an efficient alternative to conventional computational techniques of measuring the chemical potential. It also facilitates using canonical data from Brownian dynamics, molecular dynamics, or Monte Carlo simulations as a basis for constructing neural density functionals, which are fit for accurate multiscale prediction of soft matter systems in equilibrium.

The emergence of the arrow of time in quantum many-body systems stems from the inherent tendency of Hamiltonian evolution to scramble quantum information and increase entanglement. While, in principle, one might counteract this temporal directionality by engineering a perfectly inverted Hamiltonian to reverse entanglement growth, such a scenario is fundamentally unstable because even minor imperfections in the backward evolution can be exponentially amplified, a hallmark of quantum many-body chaos. Therefore, successfully reversing quantum many-body dynamics demands a deep understanding of the underlying structure of quantum information scrambling and chaotic dynamics. In this Letter, by using solid-state nuclear magnetic resonance on a macroscopic ensemble of randomly interacting spins, we measure the out-of-time-ordered correlator and validate key predictions of scramblon theory, a universal theoretical framework for information scrambling. Crucially, this theory enables us to isolate and mitigate errors in the out-of-time-ordered correlator caused by imperfections in the backward evolution. As a result, this protocol uncovers the anticipated exponential behavior of quantum many-body chaos and extracts the quantum Lyapunov exponent in a many-body experimental system for the first time. Our results push the fundamental limits of dynamical reversibility of complex quantum systems, with implications for quantum simulation and metrology.

The ambient-pressure superconductivity in ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ thin films via compressive epitaxial strain provides a highly accessible platform for diverse characterization techniques, facilitating the studies of high-temperature superconductivity. Here, we systematically map the phase diagram and reveal the superconducting dome with an electron-hole crossover in compressively strained ${\mathrm{La}}_{3-x}{\mathrm{Sr}}_x{\mathrm{Ni}}_2{\mathrm{O}}_{7-\delta }$ thin films by simultaneously tuning Sr doping and oxygen content. The maximum transition temperature ($T_c$) coincides with an anomalous sign change in the Hall coefficient ($R_H$), reminiscent of electron-doped cuprates, which may signal a Fermi surface reconstruction. Beyond the superconducting dome, a $\ln 1/T$ insulating regime and a $T$-linear resistivity regime are also resolved, resembling behaviors observed in cuprates and infinite-layer nickelates. This work reveals a dome-shaped relationship between $T_c$ and $R_H$ and establishes a key framework for understanding unconventional superconductivity in nickelate systems.