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Ferroelectric HfO2 has attracted much attention owing to its superior ferroelectricity at an ultra-thin thickness and good compatibility with Si-based complementary metal–oxide–semiconductor (CMOS) technology. However, the crystallization of polar orthorhombic phase (o-phase) HfO2 is less competitive, which greatly limits the ferroelectricity of the as-obtained ferroelectric HfO2 thin films. Fortunately, the crystallization of o-phase HfO2 can be thermodynamically modulated via interfacial stress engineering. In this paper, the growth of improved ferroelectric Al doped HfO2 (HfO2:Al) thin films on (111)-oriented Si substrate has been reported. Structural analysis has suggested that nonpolar monoclinic HfO2:Al grown on (111)-oriented Si substrate suffered from a strong compressive strain, which promoted the crystallization of (111)-oriented o-phase HfO2 in the as-grown HfO2:Al thin films. In addition, the in-plane lattice of (111)-oriented Si substrate matches well with that of (111)-oriented o-phase HfO2, which further thermally stabilizes the o-phase HfO2. Accordingly, an improved ferroelectricity with a remnant polarization (2 P r) of 26.7 μC/cm2 has been obtained. The results shown in this work provide a simple way toward the preparation of improved ferroelectric HfO2 thin films. [ABSTRACT FROM AUTHOR]

Remote sensing images carry crucial ground information, often involving the spatial distribution and spatiotemporal changes of surface elements. To safeguard this sensitive data, image encryption technology is essential. In this paper, a novel Fibonacci sine exponential map is designed, the hyperchaotic performance of which is particularly suitable for image encryption algorithms. An encryption algorithm tailored for handling the multi-band attributes of remote sensing images is proposed. The algorithm combines a three-dimensional synchronized scrambled diffusion operation with chaos to efficiently encrypt multiple images. Moreover, the keys are processed using an elliptic curve cryptosystem, eliminating the need for an additional channel to transmit the keys, thus enhancing security. Experimental results and algorithm analysis demonstrate that the algorithm offers strong security and high efficiency, making it suitable for remote sensing image encryption tasks. [ABSTRACT FROM AUTHOR]

Shear-thinning fluids have been widely used in microfluidic systems, but their internal flow mechanism is still unclear. Therefore, in this paper, molecular dynamics simulations are used to study the laminar flow of shear-thinning fluid in a microchannel. We validated the feasibility of our simulation method by evaluating the mean square displacement and Reynolds number of the solution layers. The results show that the change rule of the fluid system's velocity profile and interaction energy can reflect the shear-thinning characteristics of the fluids. The velocity profile resembles a top-hat shape, intensifying as the fluid's power law index decreases. The interaction energy between the wall and the fluid decreases gradually with increasing velocity, and a high concentration of non-Newtonian fluid reaches a plateau sooner. Moreover, the velocity profile of the fluid is related to the molecule number density distribution and their values are inversely proportional. By analyzing the radial distribution function, we found that the hydrogen bonds between solute and water molecules weaken with the increase in velocity. This observation offers an explanation for the shear-thinning phenomenon of the non-Newtonian flow from a micro perspective. [ABSTRACT FROM AUTHOR]

This paper explores a double quantum images representation (DNEQR) model that allows for simultaneous storage of two digital images in a quantum superposition state. Additionally, a new type of two-dimensional hyperchaotic system based on sine and logistic maps is investigated, offering a wider parameter space and better chaotic behavior compared to the sine and logistic maps. Based on the DNEQR model and the hyperchaotic system, a double quantum images encryption algorithm is proposed. Firstly, two classical plaintext images are transformed into quantum states using the DNEQR model. Then, the proposed hyperchaotic system is employed to iteratively generate pseudo-random sequences. These chaotic sequences are utilized to perform pixel value and position operations on the quantum image, resulting in changes to both pixel values and positions. Finally, the ciphertext image can be obtained by qubit-level diffusion using two XOR operations between the position-permutated image and the pseudo-random sequences. The corresponding quantum circuits are also given. Experimental results demonstrate that the proposed scheme ensures the security of the images during transmission, improves the encryption efficiency, and enhances anti-interference and anti-attack capabilities. [ABSTRACT FROM AUTHOR]

Due to the fact that a memristor with memory properties is an ideal electronic component for implementation of the artificial neural synaptic function, a brand-new tristable locally active memristor model is first proposed in this paper. Here, a novel four-dimensional fractional-order memristive cellular neural network (FO-MCNN) model with hidden attractors is constructed to enhance the engineering feasibility of the original CNN model and its performance. Then, its hardware circuit implementation and complicated dynamic properties are investigated on multi-simulation platforms. Subsequently, it is used toward secure communication application scenarios. Taking it as the pseudo-random number generator (PRNG), a new privacy image security scheme is designed based on the adaptive sampling rate compressive sensing (ASR-CS) model. Eventually, the simulation analysis and comparative experiments manifest that the proposed data encryption scheme possesses strong immunity against various security attack models and satisfactory compression performance. [ABSTRACT FROM AUTHOR]

Quantum dialogue (QD) enables two communication parties to directly exchange secret messages simultaneously. In conventional QD protocols, photons need to transmit in the quantum channel for two rounds. In this paper, we propose a one-step QD protocol based on the hyperentanglement. With the help of the non-local hyperentanglement-assisted Bell state measurement (BSM), the photons only need to transmit in the quantum channel once. We prove that our one-step QD protocol is secure in theory and numerically simulate its secret message capacity under practical experimental condition. Compared with previous QD protocols, the one-step QD protocol can effectively simplify the experiment operations and reduce the message loss caused by the photon transmission loss. Meanwhile, the non-local hyperentanglement-assisted BSM has a success probability of 100% and is feasible with linear optical elements. Moreover, combined with the hyperentanglement heralded amplification and purification, our protocol is possible to realize long-distance one-step QD. [ABSTRACT FROM AUTHOR]

For digital image transmission security and information copyright, a new holographic image self-embedding watermarking encryption scheme is proposed. Firstly, the plaintext is converted to the RGB three-color channel, the corresponding phase hologram is obtained by holographic technology and the watermark is self-embedded in the frequency domain. Secondly, by applying the Hilbert transform principle and genetic center law, a complete set of image encryption algorithms is constructed to realize the encryption of image information. Finally, simulation results and security analysis indicate that the scheme can effectively encrypt and decrypt image information and realize the copyright protection of information. The introduced scheme can provide some support for relevant theoretical research, and has practical significance. [ABSTRACT FROM AUTHOR]

Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure. Superalkalis have low ionization energy. Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs. In this paper, the geometry, bonding properties, electronic structure, absorption spectrum, and nonlinear optical (NLO) properties of superalkaline M 3O (M = Li, Na)-doped cyclo[18]carbon were studied by using density functional theory. M 3O and the C18 rings are not coplanar. The C18 ring still exhibits alternating long and short bonds. The charge transfer between M 3O and C18 forms stable [ M 3O]+[C18]− ionic complexes. C18 M 3O (M = Li, Na) shows striking optical nonlinearity, i.e., their first- and second-order hyperpolarizability (β vec and γ ||) increase considerably at λ = 1907 nm and 1460 nm. [ABSTRACT FROM AUTHOR]

This paper presents a novel view of the impact of electron collision off-axis positions on the dynamic properties and relativistic nonlinear Thomson inverse scattering of excited electrons within tightly focused, circularly polarized laser pulses of varying intensities. We examine the effects of the transverse ponderomotive force, specifically how the deviation angle and speed of electron motion are affected by the initial off-axis position of the electron and the peak amplitude of the laser pulse. When the laser pulse intensity is low, an increase in the electron's initial off-axis distance results in reduced spatial radiation power, improved collimation, super-continuum phenomena generation, red-shifting of the spectrum's harmonic peak, and significant symmetry in the radiation radial direction. However, in contradiction to conventional understandings, when the laser pulse intensity is relatively high, the properties of the relativistic nonlinear Thomson inverse scattering of the electron deviate from the central axis, changing direction in opposition to the aforementioned effects. After reaching a peak, these properties then shift again, aligning with the previous direction. The complex interplay of these effects suggests a greater nuance and intricacy in the relationship between laser pulse intensity, electron position, and scattering properties than previously thought. [ABSTRACT FROM AUTHOR]

Based on the substitution rule and symmetry, we propose a method to generate an octagonal quasilattice consisting of square and rhombus tiles. Local configurations and Ammann lines are used to guide the growth of the tiles in a quasiperiodic order. The structure obtained is a perfect eight-fold symmetric quasilattice, which is confirmed by the radial distribution function and the diffraction pattern. [ABSTRACT FROM AUTHOR]

We have successfully developed cryogen-free dilution refrigerators with medium cooling power that can be applied to quantum experiments. Breakthroughs have been made in some key technologies and components of heat switches and dilution units. Our prototype has been running continuously and stably for more than 100 hours below 10 mK, with a minimum temperature of 7.6 mK and a cooling power of 450 μW at 100 mK. At the same time, we have also made progress in the application of dilution refrigerators, such as quantum computing, low-temperature detector, and magnet integration. These indicators and test results indicate good prospects for application in physics, astronomy, and quantum information. [ABSTRACT FROM AUTHOR]

A novel color image encryption scheme is developed to enhance the security of encryption without increasing the complexity. Firstly, the plain color image is decomposed into three grayscale plain images, which are converted into the frequency domain coefficient matrices (FDCM) with discrete cosine transform (DCT) operation. After that, a two-dimensional (2D) coupled chaotic system is developed and used to generate one group of embedded matrices and another group of encryption matrices, respectively. The embedded matrices are integrated with the FDCM to fulfill the frequency domain encryption, and then the inverse DCT processing is implemented to recover the spatial domain signal. Eventually, under the function of the encryption matrices and the proposed diagonal scrambling algorithm, the final color ciphertext is obtained. The experimental results show that the proposed method can not only ensure efficient encryption but also satisfy various sizes of image encryption. Besides, it has better performance than other similar techniques in statistical feature analysis, such as key space, key sensitivity, anti-differential attack, information entropy, noise attack, etc. [ABSTRACT FROM AUTHOR]

Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides, which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes (TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings. [ABSTRACT FROM AUTHOR]

The FitzHugh–Nagumo neuron circuit integrates a piezoelectric ceramic to form a piezoelectric sensing neuron, which can capture external sound signals and simulate the auditory neuron system. Two piezoelectric sensing neurons are coupled by a parallel circuit consisting of a Josephson junction and a linear resistor, and a binaural auditory system is established. Considering the non-singleness of external sound sources, the high–low frequency signal is used as the input signal to study the firing mode transition and synchronization of this system. It is found that the angular frequency of the high–low frequency signal is a key factor in determining whether the dynamic behaviors of two coupled neurons are synchronous. When they are in synchronization at a specific angular frequency, the changes in physical parameters of the input signal and the coupling strength between them will not destroy their synchronization. In addition, the firing mode of two coupled auditory neurons in synchronization is affected by the characteristic parameters of the high–low frequency signal rather than the coupling strength. The asynchronous dynamic behavior and variations in firing modes will harm the auditory system. These findings could help determine the causes of hearing loss and devise functional assistive devices for patients. [ABSTRACT FROM AUTHOR]

The primary radiation damage in pure V and TiVTa concentrated solid-solution alloy (CSA) was studied using a molecular dynamics method. We have performed displacement cascade simulations to explore the generation and evolution behavior of irradiation defects. The results demonstrate that the defect accumulation and agglomeration in TiVTa CSA are significantly suppressed compared to pure V. The peak value of Frenkel pairs during cascade collisions in TiVTa CSA is much higher than that in pure V due to the lower formation energy of point defects. Meanwhile, the longer lifetime of the thermal spike relaxation and slow energy dissipation capability of TiVTa CSA can facilitate the recombination of point defects. The defect agglomeration rate in TiVTa CSA is much lower due to the lower binding energy of interstitial clusters and reduced interstitial diffusivity. Furthermore, the occurrence probability of dislocation loops in TiVTa CSA is lower than that in pure V. The reduction in primary radiation damage may enhance the radiation resistance of TiVTa CSA, and the improved radiation tolerance is primarily attributed to the relaxation stage and long-term defect evolution rather than the ballistic stage. These results can provide fundamental insights into irradiation-induced defects evolution in refractory CSAs. [ABSTRACT FROM AUTHOR]

Recently, lipid nanoparticles (LNPs) have been extensively investigated as non-viral carriers of nucleic acid vaccines due to their high transport efficiency, safety, and straightforward production and scalability. However, the molecular mechanism underlying the interactions between nucleic acids and phospholipid bilayers within LNPs remains elusive. In this study, we employed the all-atom molecular dynamics simulation to investigate the interactions between single-stranded nucleic acids and a phospholipid bilayer. Our findings revealed that hydrophilic bases, specifically G in single-stranded RNA (ssRNA) and single-stranded DNA (ssDNA), displayed a higher propensity to form hydrogen bonds with phospholipid head groups. Notably, ssRNA exhibited stronger binding energy than ssDNA. Furthermore, divalent ions, particularly Ca2+, facilitated the binding of ssRNA to phospholipids due to their higher binding energy and lower dissociation rate from phospholipids. Overall, our study provides valuable insights into the molecular mechanisms underlying nucleic acid-phospholipid interactions, with potential implications for the nucleic acids in biotherapies, particularly in the context of lipid carriers. [ABSTRACT FROM AUTHOR]

In a multi-bubble system, the bubble behavior is modulated by the primary acoustic field and the secondary acoustic field. To explore the translational motion of bubbles in cavitation liquids containing high-concentration cavitation nuclei, evolutions of bubbles are recorded by a high-speed camera, and translational trajectories of several representative bubbles are traced. It is found that translational motion of bubbles is always accompanied by the fragmentation and coalescence of bubbles, and for bubbles smaller than 10 μm, the possibility of bubble coalescence is enhanced when the spacing of bubbles is less than 30 μm. The measured signals and their spectra show the presence of strong negative pressure, broadband noise, and various harmonics, which implies that multiple interactions of bubbles appear in the region of high-intensity cavitation. Due to the strong coupling effect, the interaction between bubbles is random. A simplified triple-bubble model is developed to explore the interaction patterns of bubbles affected by the surrounding bubbles. Patterns of bubble interaction, such as attraction, repulsion, stable spacing, and rebound of bubbles, can be predicted by the theoretical analysis, and the obtained results are in good agreement with experimental observations. Mass exchange between the liquid and bubbles as well as absorption in the cavitation nuclei also plays an important role in multi-bubble cavitation, which may account for the weakening of the radial oscillations of bubbles. [ABSTRACT FROM AUTHOR]

We conduct a theoretical analysis of the massive and tunable Goos–Hänchen (GH) shift on a polar crystal covered with periodical black phosphorus (BP)-patches in the THz range. The surface plasmon phonon polaritons (SPPPs), which are coupled by the surface phonon polaritons (SPhPs) and surface plasmon polaritons (SPPs), can greatly increase GH shifts. Based on the in-plane anisotropy of BP, two typical metasurface models are designed and investigated. An enormous GH shift of about −7565.58 λ 0 is achieved by adjusting the physical parameters of the BP-patches. In the designed metasurface structure, the maximum sensitivity accompanying large GH shifts can reach about 6.43 × 108 λ 0/RIU, which is extremely sensitive to the size, carrier density, and layer number of BP. Compared with a traditional surface plasmon resonance sensor, the sensitivity is increased by at least two orders of magnitude. We believe that investigating metasurface-based SPPPs sensors could lead to high-sensitivity biochemical detection applications. [ABSTRACT FROM AUTHOR]

Dynamic topological photonics is a novel research field, combining the time-domain optics and topological physics. In this review, the recent progress and realization platforms of dynamic topological photonics have been well introduced. The definition, measurement methods and the evolution process of the dynamic topological photonics are demonstrated to better understand the physical diagram. This review is meant to bring the readers a different perspective on topological photonics, grasp the advanced progress of dynamic topology, and inspire ideas about future prospects. [ABSTRACT FROM AUTHOR]