Spectral crowding of collective motional modes limits the fidelity of entangling interactions in trapped-ion quantum processors by inducing off-resonant coupling to spectator modes. We introduce a geometric-phase entangling interaction driven by a transverse, time-dependent structured-light force. By applying the force in a plane orthogonal to the optical propagation direction, we reduce the effects of spectral crowding while preserving single-ion addressing. The scheme is compatible with arbitrary qubit encodings, provided that the qubit states experience a differential AC Stark shift. We experimentally realize high-fidelity two-qubit gates with error rates below $5\times {10}^{-3}$ in ion crystals containing up to 12 ions confined within a single potential well. These results establish gradient-field light-shift gates as a scalable approach to high-fidelity entanglement generation in spectrally crowded trapped-ion systems.

We employ terahertz Faraday magneto-optical spectroscopy to probe the relaxation dynamics of quantized helical Caroli–de Gennes–Matricon (CdGM) states in epitaxial ${\mathrm{FeTe}}_{1-x}{\mathrm{Se}}_x$ thin films, nodeless multiband superconductors with short coherence lengths in the moderately clean limit. By exploiting polarization-selective optical transitions, we directly resolve the helicity and band origin of vortex-core quasiparticles. We observe resonant transitions between long-lived CdGM states induced by radiation with opposite helicity for electronlike and holelike bands. This enables independent, band-resolved determination of quasiparticle lifetimes, vortex masses, coherence lengths, and upper critical fields, and reveals their systematic evolution with isovalent substitution $x$. The results establish terahertz magneto-optics as a direct probe of helical vortex-core excitations and provide dynamical evidence for multiband CdGM states in iron-based superconductors.

Diffraction redirects light by spatial structuring and is intrinsically chromatic, whereas reflection obeys a wavelength-independent geometric law. Here we show that a deep binary dielectric grating unifies these two principles to realize dispersion-suppressed diffraction across a broad spectral range, without invoking meta-atom group-delay engineering. The period selects a discrete family of diffraction orders that share a common output angle at distinct wavelengths, while the gap drives strong sidewall reflection that renders the modal beat length nearly insensitive to wavelength variation. Together, these two mechanisms redirect multiple discrete wavelengths into the same far-field direction with high channel efficiency and suppressed interorder leakage. Angle-resolved far-field measurements across the visible range confirm this convergence, consistent with full-wave far-field simulations.

A one-positron quantum cyclotron is realized with a single positron suspended indefinitely in the magnetic field of a Penning trap. This opens the possibility of quantum measurements of the positron magnetic moment at a precision much higher than attained with classical cyclotron motion. Comparing the magnetic moments measured using positron and electron quantum cyclotrons should provide the most stringent test of the fundamental $CPT$ invariance of the standard model of particle physics in the lepton sector.

Quantum gas microscopes offer unprecedented insights into quantum many-body states of cold atomic gases. Here we introduce concrete protocols for extending quantum gas microscopes to measure in phase space, by mapping momentum onto auxiliary degrees of freedom and using positive operator-valued measures. We distinguish between two distinct operational modes. In the Husimi-$Q$ phase-space microscope, position and momentum are jointly measured; in this mode, the fundamental quantum noise is distributed between position and momentum. Conversely, the averaged-mode phase space microscope extracts the spatial dependence of averages of the momentum density (and its moments); these averages can be retrieved with arbitrary spatial resolution. We illustrate the utility of these techniques in diverse physical settings.

We show that a bound impurity in a Bose-Einstein condensate can be directly mapped to an Unruh-DeWitt detector interacting with a relativistic quantum field. We provide explicit experimental parameters for an implementation using ${}^{41}\mathrm{K}$ impurities coupled to a ${}^{87}\mathrm{Rb}$ condensate via finite-time Feshbach tuning. As an application, we study the extraction of vacuum entanglement from distant regions of the condensate and find viable parameters for the implementation of entanglement harvesting.

Combining tight-binding theory, atom manipulation, and scanning tunneling spectroscopy, we demonstrate a quasicontinuous tuning of the flat-band energy in cluster-decorated Lieb lattices. By substituting the edge sites of Lieb lattices with tunable, rhombus-shaped four-site clusters, the emergent flat bands inherit the eigenenergies of the clusters and can be smoothly and predictably adjusted over a wide range, as verified experimentally with Fe atomic lattices on Ag(111). Our approach enables precise alignment of the flat-band energy with the Fermi level while preserving graph connectivity, providing a convenient and reliable platform for exploring emerging phenomena in quantum materials.

We experimentally demonstrate the detection of momentum transfers from individual collisions of Kr, Xe, and ${\mathrm{SF}}_6$ with an optically levitated nanoparticle, finding good agreement with theoretical expectations. The observed event rates accurately measure the gas partial pressures, while the spectral shape provides a sensitive probe of the surface properties of the nanoparticle, including its temperature. The reconstruction of impulse signals as small as $200\mathrm{keV}/c$ further establishes that levitated optomechanical sensors can reach the sensitivity required for precision measurements of fundamental particle interactions, and demonstrates a proof-of-principle for a primary pressure sensor based on the detection of individual gas particle collisions.

Commensurability and incommensurability are core concepts that permeate the field of structural superlubricity; among them, commensurate moiré patterns form a special class of configuration whose frictional properties have remained experimentally unexplored. Here we report the first direct observation of sharp friction peaks at 21.8° and 38.2° relative orientations of graphite interface corresponding to the (2, 1) commensurate moiré pattern, while other $(m,n)$ commensurate moiré patterns show no detectable signal. Unlike the observable load dependence at the coaligned commensurate state, these peaks display negligible load dependence, resembling superlubric behavior, analogous to incommensurate interface. Theoretical analysis and atomistic simulations reveal that sliding barriers decay exponentially with increasing $(m,n)$ indices, leaving only a minimal residual sliding barrier and remarkably stable interlayer separation—effectively approaching a state of “van der Waals levitation.” Our results complete the angular frictional landscape of two-dimensional homointerfaces and establish that higher-order commensurability is already sufficient to realize structural superlubricity.

Orbitronics assumes long-range orbital currents, like spin currents in spintronics. However, recent theories and experiments challenge this view, showing rather local characters for orbital polarization and importance of orbit-spin conversions. In our Letter, angular momentum is created by ferromagnetic resonance or thermal gradients in Ni/(Pt)Ti/Au heterostructures and detected by conversion to charge current. The observed charge currents are independent of Ti thickness up to 60 nm, which is incompatible with orbital transport and orbital Hall effect in Ti. Instead, they depend on both Ti interfaces, evidencing spin-mediated transport in between after and before local orbit-spin interconversions.

Electron-doped strontium titanate has emerged as a prototypical quantum ferroelectric metal. It provides a fertile ground to explore how ferroelectric instability intertwined with itinerant electrons creates quantum phenomena, including unconventional superconductivity. Despite extensive studies, the microscopic origin of the ferroelectric transition remains unsettled, with distinct interpretations based on a displacive mechanism driven by soft mode and order-disorder alignment of local dipoles. In particular, the local dipoles form nanoscale, spatially heterogeneous clusters, termed polar nanoregions, posing a significant challenge for probing or manipulating them. Here, using rotational anisotropy second harmonic generation, a symmetry-resolved probe, we quantify the orientational statistics of polar nanoregions in dilute electron-doped ${\mathrm{Sr}}_{0.95}{\mathrm{Ba}}_{0.05}{\mathrm{Ti}}_{1-x}{\mathrm{Nb}}_x{\mathrm{O}}_3$. By tracking the alignment and meltdown of polar nanoregions in thermal cycles, we unambiguously demonstrate the order-disorder nature of the ferroelectric transition. We further show that, above transition temperature, femtosecond optical fields enable deterministic control of otherwise disordered polar nanoregions, realizing reversible write and readout of polar textures on ultrafast timescales. Our findings provide new insight into ferroelectric instability and establish an all-optical route of controlling polar metal systems where conventional electrical approaches are not feasible.

We report the first robust evidence for the rotational kinematic Sunyaev-Zel’dovich (rkSZ) effect: the dipolar signal produced by the Thomson scattering of cosmic microwave background (CMB) photons off intracluster gas in dynamically active systems (including rotations and mergers). By combining CMB intensity and polarization measurements from the Planck satellite with spectroscopic member-galaxy redshifts from the Sloan Digital Sky Survey in a sample of 25 x-ray cross-matched, low-redshift ($0.02<z<0.09$), massive (${10}^{13.9}\lesssim M_{500\mathrm{c}}/M_{\odot }\lesssim {10}^{14.6}$) galaxy clusters, we detect a dipolar rkSZ signature aligned with the estimated angular momentum of each cluster, ruling out a chance fluctuation at 99.98% confidence ($3.6\sigma$). The significance of this measurement is enhanced by several new methodological improvements for isolating the rkSZ signal from primary CMB fluctuations and noise. The amplitude and shape of the signal are qualitatively consistent with predictions from state-of-the-art hydrodynamical simulations. These results establish a new tool with which to probe the dynamical state of galaxy clusters using CMB data.

Reconstruction of attosecond beating by interference of two-photon transitions is a cornerstone technique of attosecond chronoscopy, routinely used to extract photoemission delays from the phase of sideband oscillations. Here, we theoretically investigate the reconstruction of attosecond beating by interference of two-photon transitions protocol driven by quantum light and demonstrate that it is intrinsically sensitive to the quantum nature of the driving field. When the probe field is prepared in a nonclassical state, its photon statistics are imprinted onto photoelectrons via continuum-continuum transitions, giving rise to an additional time delay of several tens of attoseconds. We trace this delay to the phase associated with the second-order anomalous moment $⟨{\widehat{a}}^2⟩$ of the probe field. Extending the framework to a three-sideband configuration, which enables retrieval of the fourth-order anomalous moment $⟨{\widehat{a}}^4⟩$, we show that the interferometer exhibits significantly enhanced sensitivity to quantum fluctuations. Our work illustrates quantum attosecond photoelectron interferometry as a phase-sensitive probe of quantum light, offering a promising route for time-resolved quantum metrology at the attosecond scale.

Helicon current drive is an attractive solution for driving current to sustain steady state tokamak operation in reactor conditions. Dedicated DIII-D experiments have been conducted with a MW-level helicon system and successfully demonstrated core power deposition and current drive with helicon waves launched via a traveling wave antenna. The profile of the measured electron temperature response to helicon power injection is in good agreement with time-dependent integrated modeling that incorporates ray tracing and the effects of thermal transport simultaneously. When the helicon power is injected continuously to drive co-$I_p$ current, the reconstructed safety factor profile flattens significantly faster and sawteeth are triggered earlier than in comparison shots where the helicon is replaced by a comparable amount of electron cyclotron heating. Calculation of the helicon-driven current profile yields a peaked profile in the core, consistent with the observed power deposition profile and in good agreement with ray tracing predictions. Taken together, these experimental results represent strong evidence for the first definitive observation of auxiliary current drive due to helicon waves on any device.

A single-cycle terahertz pulse applied to single-crystal holmium iron garnet ${\mathrm{Ho}}_3{\text{Fe}}_5{\mathrm{O}}_{12}$ strongly perturbs the magneto-optical Faraday effect—an effect conventionally employed for optical readout of the magnetic state. This ultrafast perturbation sets in when cooling below the magnetization compensation temperature, where the unit cell distorts and the spins of ${\mathrm{Ho}}^{3+}$ form a noncollinear “double-umbrella” structure. The experimental dependencies reveal that the findings can be described as the ultrafast terahertz-electric-field-induced magneto-optical Faraday effect caused by the resonant excitation of crystal-field-split $f\text{−}f$ electronic transitions of ${\mathrm{Ho}}^{3+}$ in a noncentrosymmetric environment of oxygen ions. We demonstrate that the effect is not limited to ${\mathrm{Ho}}_3{\text{Fe}}_5{\mathrm{O}}_{12}$ but is also present in other rare-earth iron garnets, such as ${\mathrm{Tb}}_3{\text{Fe}}_5{\mathrm{O}}_{12}$. The effect can facilitate ultrafast optical readout of magnetic bits at a sub-100 nm spatial scale.

Strong-field ionization provides a fundamental route for probing nonlinear electron dynamics on ultrafast timescales, but it has been explored almost exclusively with classical coherent driving fields. Intense quantum light sources, particularly bright squeezed vacuum (BSV), now make it possible to ask how macroscopic photon-number fluctuations affect nonperturbative electron emission. Here, we address this question by performing shot-resolved BSV-photoelectron coincidence measurements in strong-field ionization of xenon atoms, with simultaneous access to the single-shot driving pulse intensity and the energy- and momentum-resolved photoelectron response. By calibrating the intensity-dependent ionization probability with a pulse-integrated Ammosov-Delone-Krainov response, we reconstruct the single-pulse ionization-yield distribution and quantify its fluctuations in electron momentum space. We find that intensity-conditioned BSV-driven spectra recover coherent-field-like cutoff scaling, while the reconstructed yield fluctuations increase toward higher electron energies and momenta, showing that high-energy electrons preferentially sample rare high-intensity BSV shots. Beyond ensemble-averaged spectra or photoelectron-number statistics, this approach resolves the momentum- and energy-dependent transfer of quantum-light fluctuations into atomic ionization yields. These results establish yield fluctuations as observables for strong-field quantum optics and benchmarks for theories beyond the classical-field approximation.

High-overtone bulk acoustic wave resonators (HBARs) promise advanced phononics, yet achieving nonlinearity remains challenging. We demonstrate a radiation-pressure-type parametric interaction between GHz HBARs and low-frequency flexural modes in a suspended silicon nitride membrane, where mechanical displacement modulates the external dissipation rate to enable dissipative acousto-mechanical coupling. Benefiting from the high quality factor, the system enters the resolved-sideband regime at room temperature, yielding acousto-mechanically induced transparency. We observe tunable Kerr nonlinearity and generate coherent HBAR frequency combs via two-tone driving. Notably, our dissipative coupling strength is 20 times larger than the dispersive coupling, the highest ratio among reported hybrid dissipative-dispersive coupling systems, resulting in the experimental observation of amplification in the reflection spectra under red-sideband driving. The ability to interface dense HBAR modes with a common mechanical resonator provides a scalable on-chip platform for multimode phononic information processing, with quantum phononics potentially achievable at sub-Kelvin temperatures.

In low-luminosity active galactic nuclei like M87* and Sgr A*, the accretion disk around the central supermassive black hole is tenuous and collisionless. As a result, the usual ideal magnetohydrodynamics approximation may not be applicable. In this Letter, we report on the first fully kinetic simulations of the accretion process where the plasma initially has finite angular momentum, focusing on the case of axisymmetry. The simulated accretion flow behaves remarkably similarly to the magnetically arrested disk regime of ideal magnetohydrodynamics, reproducing episodes of magnetic flux saturation and eruption typical of magnetically arrested disks. The resemblance to fluid models owes largely to kinetic instabilities, which regulate pressure anisotropy in the disk, allowing fluid terms to dominate the angular momentum transfer. In addition, by handling vacuum regions effectively, our kinetic approach probes the matter supply to the jet funnel. We observe no efficient penetration of the accreting material into this region, suggesting that a pair discharge may be required to sustain the Blandford-Znajek process. These initial findings represent important groundwork to be checked and built upon by future kinetic accretion simulations, especially in 3D.

Biological valves control the directionality of oscillatory or fluctuating internal flows by deforming (reversibly) to stop flow. To uncover the physical basis for flow rectification in these systems, we introduce a simple physical mimic of the mitral heart valve that is shaped like a soft conical shell in an impinging flow. Combining ex vivo porcine-heart and in vitro conical valve experiments, we show how noise-activated buckling deformations serve to rectify the flow. We quantitatively explain our observations using a minimal elastohydrodynamic theory for valve closure that leads to a dynamical bifurcation driven by stochastic hydrodynamic forces. Our theory also suggests that valve collapse can be triggered on demand, which we corroborate using experiments. Together, these results suggest a design principle for the efficient operation of soft valves.