The coalescence of liquid drops is a fundamental process that remains incompletely understood, particularly in the intermediate regimes where capillary, viscous, and inertial forces are comparable. Here, we experimentally investigate the dynamics of drop-to-drop coalescence during the transition between viscous and inertial regimes using high-speed imaging. Our results reveal that the liquid bridge between droplets shows power-law growth with exponents between 1/2 and 1 during drop coalescence. We propose an alternative scaling approach using a dimensionless crossover function that smoothly transitions between viscous and inertial limits. This simple approach, inspired by previous work on drop impact, successfully collapses the experimental data for a wide range of liquid viscosities and coalescence times onto a single master curve. We further compare our results with recent theoretical models and demonstrate how our approach complements and extends current understanding in the crossover of drop coalescence. This study contributes to both the fundamental physics of drop coalescence and its practical applications in various industrial processes.

Despite progress towards achieving low error rates with superconducting qubits, error-prone two-qubit gates remain a bottleneck for realizing large-scale quantum computers. Therefore, a systematic framework to design high-fidelity gates becomes imperative. One type of two-qubit gate in superconducting qubits is the controlled-phase (cphase) gate, which utilizes a conditional interaction between higher-energy levels of the qubits controlled by a baseband flux pulse on one of the qubits or a tunable coupler. In this work, we study an adiabatic implementation of cphase gates and formulate the design of the control trajectory for the gate as a pulse-design problem. We show in simulation that the Chebyshev-based trajectory can, in certain cases, enable gates with gate infidelity lower by an average of $23.3\mathrm{\%}$ when compared to the widely used Slepian-based trajectory.

Towards the development of strategies for tailoring spin-wave band gaps in magnonic crystals, this work examines the band-gap properties in a one-dimensional magnonic crystal with double periodicity. A long and narrow yttrium iron garnet thin film strip is etched with an array of transverse groove lines separated by alternating distances, where the second distance is twice the first. This double periodicity in the magnonic crystal translates into dissimilar band gaps in the frequency domain, with the third and sixth band gaps being more pronounced than others. These band gaps are more pronounced because the corresponding wave numbers simultaneously satisfy the Bragg scattering conditions for the periods equal to the two groove separations as well as their sum. Experimental observations are reproduced by numerical simulations. Together, the experimental and numerical results demonstrate how multiple periodicities could be an effective design parameter for creating magnonic crystals with desired band gaps.

We propose a simple scheme for a dual-linearly-polarized metagrating achieved through an orthogonally embedded gratings approach that allows efficient coupling of the incident electromagnetic wave to the desired channel even at near-grazing angles. The diffraction properties of the scatterers are discussed primarily over an angular coverage from 50° to 80°. An exemplary metagrating-assisted hybrid metalens with a near-unity numerical aperture (0.987) is then numerically and experimentally demonstrated. Compared with conventional gradient metalenses, this design offers comprehensively improved focusing quality, including focusing efficiency and intensity. The proposed method can readily be extended to other frequencies from millimeter wave to optical frequencies, providing a promising platform for device designs in communication and imaging systems, as well as applications such as sensing, signal processing, and high-density data recording.

The design of asymmetric tunneling barriers in ultrathin ferroelectric tunnel junctions (FTJ) using two-dimensional (2D) materials is crucial for realizing large on:off ratios in miniaturized nonvolatile memory devices. This work investigates the impact of the contact interlayer on device performance in 2D FTJs based on van der Waals heterostructures composed of ferroelectric and 2D transition-metal dichalcogenides as contact interlayers. First-principles quantum transport simulations reveal that the contact interlayer creates asymmetric charge screening in the contact electrodes, enabling effective modulation of the tunneling barrier through ferroelectric polarization switching. A giant tunneling electroresistance ratio reaching 8 × ${10}^7$% is achieved in FTJ devices incorporating ${\mathrm{Sn}\mathrm{Se}}_2$ and doped ${\mathrm{Mo}\mathrm{S}}_2$ contact interlayers, attributed to their highly tunable band alignment with α-${\mathrm{In}}_2{\mathrm{Se}}_3$. The results also indicate that doping of the contact interlayer effectively modulates the screening of the asymmetric contact and significantly alters the tunneling barrier, offering a practical approach to enhancing FTJ performance via interface charge engineering.

The accurate modeling of mode hybridization and calculation of radiative relaxation rates have been crucial to the design and optimization of superconducting quantum devices. In this work, we introduce a spectral theory for the electrohydrodynamics of superconductors that enables the extraction of the relaxation rates of excitations in a general three-dimensional distribution of superconducting bodies. Our approach addresses the long-standing problem of formulating a modal description of open systems that is both efficient and allows second quantization of the radiative hybridized fields. This is achieved through the implementation of finite but transparent boundaries through which radiation can propagate into and out of the computational domain. The resulting spectral problem is defined within a coarse-grained formulation of the electrohydrodynamical equations that is suitable for the analysis of the nonequilibrium dynamics of multiscale superconducting quantum systems.

We present an innovative robotic device designed to provide controlled motion for studying active matter. Motion is driven by an internal vibrator powered by a small rechargeable battery. The system integrates acoustic and magnetic sensors along with a programmable microcontroller. Unlike conventional vibrobots, the motor induces horizontal vibrations, resulting in cycloidal trajectories that have been characterized and optimized. Portions of these orbits can be utilized to create specific motion patterns. As a proof of concept, we demonstrate how this versatile system can be exploited to develop active particles with varying dynamics, ranging from ballistic motion to run-and-tumble diffusive behavior.

The control of fluids is a crucial aspect of modern engineering, where hydrodynamic metamaterials have emerged as transformative solutions for flow manipulation. However, until now, the design of hydrodynamic metamaterials has been limited to Newtonian fluids, lacking exploration of non-Newtonian fluids. In this study, we explore cloak designs for power-law and Bingham fluids within a Hele-Shaw cell using transformation theory. We establish a generalized transformation framework enabling anisotropic and isotropic material cloaks for power-law and Bingham fluids in Hele-Shaw configurations. The derived tensor-invariance conditions reveal unidirectional cloaking capability dictated by a pressure-gradient-orientation dependence. Simulations validate our findings. In contrast to traditional nonlinear transformation theories centered on potential-dependent diffusion systems, our theory extends to gradient-field-dependent scenarios and offers insights into the design of systems across various physical domains.

Silicon-based diodes are fundamental components in modern semiconductor technology. However, their performance is hindered by the Boltzmann switching limit, resulting in an ideality factor larger than 1 and a high operating voltage. In this work, we propose a silicon cold-source diode (CSD) to realize energy-efficient switching with subunity ideality factor. The silicon cold-source diode integrates a $p$-$n$ junction with a cold source comprised of a metal layer sandwiched between $N$-type and $P$-type silicon. Through first-principles transport calculations, it is demonstrated that the silicon cold-source diode can enable low-energy carrier injection and enhanced current by adjusting the doping concentration and varying the metal material. The CSDs can realize a subunity ideality factor, as low as 0.79. The operating voltage can be further reduced to 0.4 V. At the same time, the rectification characteristics can also be improved with the on-off current ratio exceeding ${10}^9$. By optimizing the metal layer, on-state current comparable to $p$-$n$ diode can be achieved in CSDs. We have designed potential preparation processes for CSDs and analyzed the associated challenges. The doping concentration in the $N$-type and $P$-type regions is critical to device performance. Insufficient doping concentration leads to significant performance degradation. These findings serve as a valuable framework for the design and optimization of cold-source diodes compatible with CMOS technology, particularly tailored for low-power applications.

Efficient verification of entangled states is crucial to many applications in quantum information processing. However, the effectiveness of standard quantum state verification (QSV) is based on the condition of independent and identical distribution (IID), which impedes its applications in many practical scenarios. Here we demonstrate a defensive QSV protocol, which is effective in all kinds of non-IID scenarios, including the extremely challenging adversarial scenario. To this end, we build a high-speed preparation-and-measurement apparatus controlled by quantum random-number generators. Our experiments clearly show that standard QSV protocols often provide unreliable fidelity certificates in non-IID scenarios. In sharp contrast, the defensive QSV protocol based on a homogeneous strategy can provide reliable and nearly tight fidelity certificates at comparable high efficiency, even under malicious attacks. Moreover, our scheme is tolerant of the imperfections in a realistic experiment, which is very appealing to practical applications.

We experimentally demonstrate a protocol that effectively suppresses low-frequency noise, including the qubit-bath interaction in diamond. This enables the detection of ac signals below 1 MHz with an increased signal-to-noise ratio of up to approximately 17. The method is based on ac magnetometry with single- and doubly dressed states, which are adiabatically transferred from the initial bare qubit states via concatenated continuous dynamical decoupling. We compare the dressed-state protocols with a conventional pulsed dynamical decoupling method, XY16. This work paves an alternative way toward the sensitive detection of weakly coupled nuclear spins in low-field NMR experiments and submegahertz ac magnetometry.

Quantum network coding provides a solution for information transmission at bottleneck channels. However, the single-path scheduling approach is hampered in the face of massive data transmission demands, which is particularly challenging in large-scale network communication scenarios. Here we propose a continuous-variable quantum network coding (CVQNC) scheme for parallel transmission of multiple quantum states based on optical frequency combs. The quantum communication channel is naturally constructed due to the nonclassical correlations exhibited by the symmetric sideband modes at around half the pump frequency on the squeezed field. Source nodes with preshared multiplex entanglement enable the transmission of multiple quantum states in parallel and simultaneously, which increases the channel capacity of the network and relieves the single-path transmission pressure. In particular, fidelity is calculated as a critical measure of transmission performance, and we provide a method to increase fidelity using photon catalysis, along with squeezing parameters and beam splitter transmittance for non-Gaussian source states at optimal fidelity. Furthermore, the channel capacity and fidelity of the CVQNC system are predicted on the basis of the $k$-nearest neighbor algorithm, and the predicted data match well with the actual derivation.

Inspired by recent advancements in simulating periodic systems on quantum computers, we develop an approach to further advance the simulation of these systems, named (SC)${}^2$-ADAPT-VQE. Our approach extends the scalable-circuits ADAPT-VQE framework, which builds an ansatz from a pool of coordinate-invariant operators defined for arbitrarily large, though not arbitrarily small, volumes. Our method uses a classically tractable “surrogate constructed” method to remove irrelevant operators from the pool, reducing the minimum size for which the scalable circuits are defined. Bringing together the scalable circuits and the surrogate constructed approaches forms the core of the (SC)${}^2$ methodology. Our approach allows for a wider set of classical computations on small volumes, which can be used for a more robust extrapolation protocol. While developed in the context of lattice models, the surrogate construction portion is applicable to a wide variety of problems where information about the relative importance of operators in the pool is available. As an example, we use it to compute the properties of the Schwinger model—quantum electrodynamics for a single, massive fermion in $1+1$ dimensions—and show that our method can be used to accurately extrapolate to the continuum limit.

Charge transport in disordered organic semiconductors is determined by charge carriers hopping through a series of molecules in an energetically disordered landscape, which can be viewed as a percolation problem in a three-dimensional network. Using combined three-dimensional kinetic Monte Carlo simulation and fat percolation theory, we systematically investigated the effect of variable-range hopping (VRH) on percolative charge transport in disordered organic semiconductors. Material dilution is a commonly used technique for bulk heterojunction optoelectronic devices, and has recently been proposed as a method for achieving a high-efficiency charge transport layer in light-emitting devices. In diluted materials, competition between energetic disorder–dominated percolation and spatial site disorder–dominated percolation needs to be clarified, which is theoretically identified and discussed in detail in this work. We find that for realistic molecular wave-function decay lengths, VRH plays a significant role in charge transport. At low temperatures or low active material fractions, VRH becomes even more important. Exponentially shaped deep trap states can further enhance VRH especially at low temperatures. With materials becoming more diluted, energetic disorder–dominated percolation gradually transforms into spatial site disorder–dominated percolation.

Vortex-based single-beam tweezers have the ability to precisely and selectively move a wide range of objects, including particles, bubbles, droplets, and cells with sizes ranging from the millimeter to micrometer scale. In 2017, Karlsen and Bruus [Phys. Rev. Appl. 7, 034017 (2017)] theoretically suggested that these tweezers could also address one of the most challenging issues: the patterning and manipulation of miscible fluids. In this paper, we experimentally demonstrate this ability using acoustic vortex beams generated by interdigital transducer-based active holograms. The experimental results are supported by a numerical model based on acoustic body force simulations. This work paves the way for the precise shaping of chemical concentration fields, a crucial factor in numerous chemical and biological processes.

A macroscopic square artificial spin ice (ASI) is a collection of bar magnets placed in a square lattice arrangement. Each magnet is supported by hinges that allow its mechanical rotation. Previous investigations in these structures have shown ground-state configurations and driven dynamics similar to those of their nanosized counterparts. Here we numerically investigate the impact of the wave dynamics of a uniform state and the impact of a domain wall on the driven dynamics. We find that waves quickly lose coherence by scattering between modes in this system. In addition, we observe a distinct mode associated with the isolated oscillation at the domain wall. As expected from spatial localization, this resonant mode is under the band of propagating waves in the macroscopic square ASI. The results are analogous to the development of low-frequency edge modes in nanoscopic spin ices in the presence of defects. Our results provide valuable insight into the physics of mechanomagnetic systems, demonstrating the existence of wave scattering and spatial confinement phenomena in macroscopic square ASIs.

A perturbative ac field superposed on a dc bias ($J_b$) is known to excite the Higgs mode in superconductors. The dirty limit, where disorder enhances the Higgs resonance, provides an ideal setting for this study and is also relevant to many superconducting devices operating under strong dc biases. However, the effects of a strong dc bias near the depairing current in dirty-limit superconductors remain largely unexplored, despite their significance in both fundamental physics and applications. In this paper, we derive a general formula for the complex conductivity of disordered superconductors under an arbitrary dc bias using the Keldysh-Usadel theory of nonequilibrium superconductivity. This formula is relatively simple, making it more accessible to a broader research community. Our analysis reveals that in a strongly dc-biased dirty-limit superconductor, the Higgs mode induces an instability in the homogeneous superflow within a specific frequency window, making the high-current-carrying state vulnerable to ac perturbations. This instability, which occurs exclusively in the $\mathrm{ac}\parallel \mathrm{dc}$ configuration, leads to a nonmonotonic dependence of kinetic inductance on frequency and bias strength. By carefully tuning the dc bias and the frequency of the ac perturbation, the kinetic inductance can be enhanced by nearly 2 orders of magnitude. In the weak-dc-bias regime, our formula recovers the well-known quadratic dependence, $L_k\propto 1+C(J_b/J_{\mathrm{dp}}{)}^2$, with coefficients $C=0.409$ for $\mathrm{ac}\parallel \mathrm{dc}$ and $C=0.136$ for $\mathrm{ac}\perp \mathrm{dc}$, where $J_{\mathrm{dp}}$ is the equilibrium depairing current density. These findings establish a robust theoretical framework for dc-biased superconducting systems and suggest that Higgs-mode physics could be exploited in the design and optimization of superconducting detectors. Moreover, they may lead to a yet-to-be-explored detector concept based on Higgs-mode physics.