We solve robot-trajectory planning problems at industry-relevant scales. Our end-to-end solution integrates highly versatile random-key algorithms with model stacking and ensemble techniques, as well as path relinking for solution refinement. The core optimization module consists of a biased random-key genetic algorithm. Through a distinct separation of problem-independent and problem-dependent modules, we achieve an efficient problem representation, with a native encoding of constraints. We show that generalizations to alternative algorithmic paradigms such as simulated annealing are straightforward. We provide numerical benchmark results for industry-scale data sets. Our approach is found to consistently outperform greedy baseline results. To assess the capabilities of today’s quantum hardware, we complement the classical approach with results obtained on quantum annealing hardware, using qbsolv on Amazon Braket. Finally, we show how the latter can be integrated into our larger pipeline, providing a quantum-ready hybrid solution to the problem.

Active x-ray inspections have great potential for noninvasive detection of illicit materials. Dual-energy x-ray radiography, in particular, has been used to determine material composition by utilizing the energy-dependence of the x-ray attenuation coefficients. However, current implementations of this method are limited in their ability to determine the material composition of composite objects. Here we present an inverse algorithm that uses multienergy x-ray radiography data to noninvasively reconstruct the contents of a container. A critical feature of the current contribution is that material identification can be performed using conventional detectors and x-ray spectra with different endpoint energies produced by varying nothing more than the tube voltage. Adaptive regularization is used to increase the accuracy of material estimations from multienergy data sets. The utility of these methods is demonstrated with experimentally acquired radiographs obtained using a tunable x-ray source that produces spectra with endpoint energies of 100–450 keV. The object inspected is a scale model of a nuclear materials storage container composed of three-dimensional printed plastic and stainless-steel spheres inside a thin-walled steel container. Reconstructions of the steel sphere thicknesses are within a root-mean-square error of 0.37 cm.

The design for an inductive superconducting quantum interference proximity transistor with enhanced performance, the L-SQUIPT, is presented and analyzed. The interferometer is based on a double-loop structure, where each ring comprises a superconductor–normal-metal–superconductor mesoscopic Josephson weak link and the readout electrode is implemented in the form of a superconducting tunnel probe. Our design allows us to both improve the coupling of the transistor to the external magnetic field and increase the characteristic magnetic flux transfer functions, thereby leading to an improved ultrasensitive quantum limited magnetometer. The L-SQUIPT behavior is analyzed in both the dissipative and the dissipationless Josephson-like operation modes, in the latter case by exploiting both an inductive and a dispersive readout scheme. The improved performance makes the L-SQUIPT promising for magnetic flux detection as well as for specific applications in quantum technology, where a responsive dispersive magnetometry at millikelvin temperatures is required.

Midinfrared light is extensively used for identifying molecules because their characteristic vibrational modes commonly exist in the midinfrared spectral region. In this paper, a midinfrared quantum cascade laser is utilized for sorting silica particles with resonant enhancement of the optical force by exciting their vibrational mode. Silica particles on an evanescent wave drift rapidly along the prism surface, whereas identical-sized polystyrene particles drift at 7–10 times lower speed. We suggest the application of this principle for optical force chromatography in the midinfrared region.

We design an acoustic switch based on a spiral kirigami metasurface using numerical simulations and evaluate its performance experimentally. By etching an Archimedean spiral on a thin aluminum sheet, a band gap in out-of-plane vibration modes can be generated. The band gap is significantly suppressed by axially stretching the kirigami spiral structure, extending sound propagation to a broader frequency range. The kirigami metasurface is easily deformed and manipulated and can switch the energy transmission on and off in the desired operating-frequency range, providing an alternative design strategy for acoustic metasurfaces.

We demonstrate and study a microcell microwave atomic clock based on optical-microwave double resonance (DR) interrogation operated in a pulsed Ramsey scheme, called the μPOP clock, based on a microfabricated Rb vapor cell and a micro-loop-gap microwave resonator. For the mm-scale dimensions of this cell, the population and coherence relaxation rates of the Rb clock transition are on the order of 4–5 kHz, which puts constraints on the useful Ramsey times and overall pulse sequence in view of optimized clock performance. Our proof-of-principle demonstration of the μPOP clock shows that the pulsed DR approach is nevertheless feasible and results in a short-term clock stability of 1 × ${10}^{-11}$ τ${}^{-1/2}$ and reaching the ≤2 × ${10}^{-12}$ level at timescales of 1000 s to one day. The short-term instability budget established for the μPOP clock shows that the main limitation to the short-term stability arises from the detection noise. Thanks to the pulsed Ramsey scheme, light-shift effects are strongly reduced in the μPOP clock, which opens perspectives for further improvements of long-term clock stability, in view of future generations of miniature vapor-cell clocks with enhanced performances based on the DR scheme.

We present the concept of the optomagnonic logic gate, where interference of spin waves excited by femtosecond laser pulses at multiple points by the inverse Faraday effect in a bismuth-substituted yttrium iron garnet film plays a decisive role. The resulting spin-wave distribution is determined by constructive and destructive interference, which is controlled by the polarization of laser sources. A variable platform with a spatial light modulator is used to control the overall spin-wave distribution by manipulating the arrangement of the local spin-wave sources. We demonstrate the experimental optical excitation of backwards volume magnetostatic spin waves at multiple points and use wavelet analysis and micromagnetic numeric simulations to analyze them. Simulations provide an excellent agreement with the experimental data and are further used to model the magnon logical gate (xnor) based on optically excited spin-wave interference.

We propose a scheme to implement the phase-robust topological router based on a one-dimensional dimerized superconducting circuit lattice with long-range hopping. We show that the proposed dimerized superconducting circuit lattice can be mapped into an extended chiral-symmetric Su-Schrieffer-Heeger (SSH) model with long-range hopping, in which the existence of long-range hopping induces a special zero-energy mode. The peculiar distribution of the zero-energy mode enables us to engineer a phase-robust topological router, which can achieve quantum state transfer (QST) from one site (input port) to multiple sites (output ports). Benefiting from the topological protection of chiral symmetry, we demonstrate that the presence of the mild disorder in nearest-neighbor and long-range hopping has no appreciable effects on QST in the lattice. Particularly, after introducing another long-range hopping into the extended SSH lattice, we propose an optimized protocol of the phase-robust topological router, in which the number of the output ports can be efficiently increased. Resorting to the Bose statistical properties of the superconducting circuit lattice, the input port and output ports assisted by the zero-energy mode can be detected via the mean distribution of the photons. Our work breaks the traditional QST form with only one outport by the zero-energy mode and opens a pathway to construct large-scale quantum information processing in the SSH chains with long-range hopping.

MXene has emerged as one of the frontier two-dimensional materials. In this work, ${\mathrm{Ti}}_3{\mathrm{C}}_2{T}_2(T=-\mathrm{O},-\mathrm{Cl},-\mathrm{OH}$, or $-\mathrm{F})$ MXene-${\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ perovskite heterostructures are constructed, and the various surface terminations of ${\mathrm{Ti}}_3{\mathrm{C}}_2{T}_2$ can achieve functionalized perovskite optoelectronic applications in the heterostructures. Lattice-mismatch rates of the ${\mathrm{Ti}}_3{\mathrm{C}}_2{T}_2$ and ${\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ heterostructures are only about 1%, which makes the electronic properties of ${\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ independent of lattice stress in the heterostructures. The binding energies of the ${\mathrm{Ti}}_3{\mathrm{C}}_2{T}_2/{\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ interfaces are quite low, especially at the ${\mathrm{Ti}}_3{\mathrm{C}}_2(\mathrm{OH}{)}_2/{\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ interface. Due to the adjustable work function (WF) of ${\mathrm{Ti}}_3{\mathrm{C}}_2{T}_2$, the types of interface contacts are different, including n- and p-type Schottky contacts and an ohmic contact. The ${\mathrm{Ti}}_3{\mathrm{C}}_2(\mathrm{OH}{)}_2/{\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ interface is an ohmic contact; this is attributed to the big difference in the WFs of ${\mathrm{Ti}}_3{\mathrm{C}}_2(\mathrm{OH}{)}_2$ and ${\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$, which could greatly boost the charge-carrier separation and transfer efficiency. In addition, the constructed heterostructures enhance the optical absorption coefficient and reduce charge-carrier effective masses. These results indicate that the ${\mathrm{Ti}}_3{\mathrm{C}}_2{T}_2/{\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$ heterostructures, especially ${\mathrm{Ti}}_3{\mathrm{C}}_2(\mathrm{OH}{)}_2/{\mathrm{Cs}}_3{\mathrm{Bi}}_2{\mathrm{Br}}_9$, can significantly improve the optoelectronic performance of the lead-free perovskite.

The possibility of controlling Josephson vortices and fluxon states has always been an attractive area of research that can influence the development of superconducting devices and quantum computing. Here we demonstrate the capability of magnetic force microscopy to detect and manipulate Josephson vortices (JVs) and fluxons below the critical current in complex superconducting systems on the example of a dc superconducting quantum interference device. The simultaneous magnetic force microscopy and transport investigation method make it possible to generate JVs by direct current in Josephson junctions and simultaneously analyze their dynamics under various external conditions. Our results show a dynamic process of transition of $2\pi$-phase singularities of JVs and fluxons from one to another. Finally, we demonstrated that the magnetic force microscopy method could distinguish the difference in critical currents between several Josephson junctions in complex superconducting circuits without the need of direct electron transport measurements.

What is the fate of an oscillator when its inductance and capacitance are varied while its frequency is kept constant? Inspired by this question, we propose a protocol to implement parity-time ($\mathcal{P}\mathcal{T}$) symmetry in a lone oscillator. Different forms of constrained variations lead to static, periodic, or arbitrary balanced gain and loss profiles, that can be interpreted as purely imaginary gauge fields. With a state-of-the-art, dynamically tunable $LC$ oscillator comprising synthetic circuit elements, we demonstrate static and Floquet $\mathcal{P}\mathcal{T}$ breaking transitions, including those at vanishingly small gain and loss, by tracking the circuit energy. Concurrently, we derive and observe conserved quantities in this open, balanced gain-loss system, both in the static and Floquet cases. Lastly, by measuring the circuit energy, we unveil a giant dynamical asymmetry along exceptional-point contours that emerge symmetrically from the Hermitian degeneracies at Floquet resonances. Distinct from material or parametric gain and loss mechanisms, our protocol enables on-demand parity-time symmetry in a minimal classical system—a single oscillator—and may be ported to other realizations including metamaterials and optomechanical systems.

In this work, we develop upper bounds on key rates for device-independent quantum key distribution (DI-QKD) protocols and devices. We study the reduced $\mathrm{cc}$-squashed entanglement and show that it is a convex functional. As a result, we show that the convex hull of the currently known bounds is a tighter upper bound on the device-independent key rates of the standard Clauser-Horne-Shimony-Holt (CHSH)-based protocol. We further provide tighter bounds for DI-QKD key rates achievable by any protocol applied to the CHSH-based device. This bound is based on reduced relative entropy of entanglement optimized over decompositions into local and nonlocal parts. In the dynamical scenario of quantum channels, we obtain upper bounds for device-independent private capacity for the CHSH-based protocols. We show that the device-independent private capacity for the CHSH-based protocols on depolarizing and erasure channels is limited by the secret key capacity of dephasing channels.

Optical cavities find diverse uses in lasers, frequency combs, optomechanics, and optical signal processors. Complete reconfigurability of the resonant frequency as well as the loss enables development of generic field programmable cavities for achieving the desired performance in these applications. Conventional reconfigurable cavities are generally limited to specific material platforms or specific optical tuning methods and require sophisticated fabrication. Furthermore, the tuning of the loss is coupled to the resonance shift in the cavity. We propose and demonstrate a simple and generic interferometer in a cavity structure that enables quasiperiodic modification of the internal cavity loss and the cavity resonance to reconfigure the $Q$ factor, transmission characteristics, and group delay of the hybrid cavity, with simple tuning of the optical phase in the interferometer. We also demonstrate methods to decouple the tuning of the loss from the resonance shift, that enables resonance-locked reconfigurability. This structure also enables resonance shift to both shorter and longer wavelengths using the same phase-tuning technique, which is challenging to achieve in conventional reconfigurable cavities. These devices can be implemented in any guided-wave platform (on-chip or fiber-optic) with potential applications in programmable photonics and reconfigurable optomechanics.

Increasing the energy density in electric double-layer capacitors (EDLCs), also known as supercapacitors, remains an active area of research. Specifically, there is a need to design and discover electrode and electrolyte materials with enhanced electrochemical storage capacity. Here, using fully atomistic molecular dynamics (MD) simulations, we investigate the performance of hyper-branched “poly(amidoamine) (PAMAM)” dendrimer as an electrolyte and an electrode coating material in a graphene-based supercapacitor. We investigate the performance of the capacitor using two different modeling approaches, namely the constant charge method (CCM) and the constant potential method (CPM). These simulations facilitated the direct calculation of the charge density, electrostatic potential, and field, and hence the differential capacitance. We found that the presence of the dendrimer in the electrodes and the electrolyte increased the capacitance by about $65.25\mathrm{\%}$ and $99.15\mathrm{\%}$, respectively, compared with the bare graphene electrode-based aqueous EDLCs. Further analysis revealed that these increases were due to the enhanced electrostatic screening and reorganization of the double-layer structure of the dendrimer-based electrolyte.

Piezoelectric optomechanical platforms present one of the most promising routes towards efficient transduction of signals from the microwave to the optical frequency domains. While there has been significant recent progress particularly on the materials front, alternative device architectures that can potentially meet the stringent efficiency requirements of quantum transducers need to be continuously explored. In this work, we utilize the mechanical supermode principle to improve the overall microwave-to-optical transduction efficiency, by fabricating Lamb-wave resonators that are hybridized with the mechanical breathing modes of a rib waveguide in a suspended gallium arsenide ($\mathrm{Ga}\mathrm{As}$) photonic-integrated-circuit platform. Combining the strong elasto-optic interactions available in $\mathrm{Ga}\mathrm{As}$ with the increased phonon injection efficiency enabled by this architecture, we demonstrate signal transduction up to 7 GHz, and an increase in transduction efficiency of approximately 25 times for the hybridized mode ($f_m\approx 2$ GHz), using this approach. We also outline routes for improving device performance to enable quantum transduction within this platform.

A topological Fano resonance with ultrasharp asymmetric line shape is sensitive to external parameters and is immune to structural disorder, and thus, acts as a robust sensor. Here, an ultracompact tunable on-chip integrated topological Fano resonance is designed based on graphene-based nanomechanical phononic crystals. The Fano resonance comes from the interference between topologically protected even and odd edge modes at the interface between trivial and nontrivial insulators. The two edge modes have different edge-mode widths, resulting in distinct resonant lifetimes. The resonant frequency can be adjusted by employing different gate voltages, which can vary the tension of the graphene membrane. Such tunable topological Fano resonances can be applied to design a wide variety of highly sensitive and accurate robust sensors, including extremely tiny forces, masses, and spatial positions.

We propose a high-resolution label-free two-dimensional imaging method by introducing second-harmonic generation (SHG) and structured illumination in quantitative phase microscopy (QPM), termed ${\mathrm{S}}^2\mathrm{QPM}$, which can achieve a fourfold lateral resolution improvement compared with normal incident illumination for noncentrosymmetric structures. Unlike traditional QPM only obtaining information about the optical path difference, ${\mathrm{S}}^2\mathrm{QPM}$ can additionally recover structural information from the ${\chi }^{(2)}$ distribution. Analytical solutions for SHG fields are obtained by solving the inhomogeneous and nonlinear Helmholtz equation in the $\mathit{k}$-space in a both concise and accurate way. With the $\mathit{k}$-space SHG field solutions for different structured illumination patterns, an object reconstruction model is developed to retrieve the high-resolution normalized ${\chi }^{(2)}$ distributions and quantitative phase maps. We simulate high-resolution reconstructions of the normalized ${\chi }^{(2)}$ distributions and quantitative phase maps using various resolution targets. The lateral resolution improvement is quantified by synthesizing the object spectrum function and profiling resolution targets.

Drying plays a central role in various fabrication processes and applications of functional nanoporous materials, most prominently in relation to energy storage and conversion. During such processes, liquid coexists with air inside the sample, leading to transport as a result of concentration gradients of vapor and/or liquid. Experimentally, it is extremely challenging to unravel this transport phenomenology inside the hidden geometry of porous media. Here, we observe the drying of a model nanoporous material (monolithic mesoporous silica glass, Vycor) with magnetic resonance imaging. We show that, for various boundary conditions (air-flux intensities), no dry region develops, but the sample desaturates in depth. This desaturation is almost homogeneous throughout the sample for weak air flux, while saturation gradients can be observed for sufficiently strong air flux. We demonstrate that the transport of water is mainly ensured by liquid flow towards the free surface, resulting from a gradient of vapor pressure, associated with local saturation (via the desorption curve), leading to a gradient of liquid pressure (via the Kelvin law). Assuming otherwise standard hydrodynamic characteristics of the nanoconfined liquid, this results in a diffusionlike model, which appears to represent experimental data very well in terms of the spatial distribution of water over time inside the sample for various boundary conditions (air-flux intensities). Finally, we propose a predictive model of the detailed drying characteristics of a nanomaterial from knowledge of its pore size, permeability, and desorption curve. This provides an insight into the rational design of drying-based processes employing functional nanoporous materials and allows for a mechanistic understanding of drying phenomenologies in natural nanoporous media.

Quantum key distribution (QKD) allows two remote parties to share information-theoretically secure keys. In recent years, a revolutionary breakthrough called twin-field (TF) QKD has been developed to overcome the linear key-rate constraint and greatly increases the achievable distance. Phase randomization and subsequent postselection play roles in its security proof. Later, no-phase-postselection TF QKD was proposed and became a popular variant, since the removal of phase postselection leads to a higher key rate. However, the achievable distance is decreased compared to the original one. Here, we propose a TF QKD protocol with partial phase postselection. Namely, its code mode is still free from global phase randomization and postselection to make sure the advantage of the high key rate remain. On the other hand, phase postselection is introduced in the decoy mode to improve the performance. Applying an operator dominance condition, we prove universal security of the proposed protocol in the finite-key case under coherent attacks, and numerical simulations confirm its potential advantages in terms of key rate and achievable distance.