Search Results (53)

Conventional public-key cryptographic systems are increasingly threatened by advances in quantum computing, accelerating the need for robust post-quantum cryptographic solutions. Among these, Falcon, a compact lattice-based digital signature scheme, has emerged as a leading candidate in the NIST post-quantum standardization process due to its efficiency and theoretical security grounded in hard lattice problems. This work introduces Falcon-M, a modified version of the Falcon algorithm that significantly reduces implementation complexity. It does so by replacing Falcon’s intricate trapdoor-based key-generation mechanism with a simplified approach that utilizes randomized polynomial Gaussian sampling and fast Fourier transform (FFT) operations. Falcon-M incorporates SHA-512 hashing and discrete Gaussian sampling to preserve cryptographic soundness and statistical randomness while maintaining the core structure of Falcon’s signing and verification processes. We formally specify the Falcon-M algorithm, provide an updated pseudocode, and offer a comparative analysis with the original Falcon in terms of algorithmic complexity, security assumptions, and implementation overhead. Additionally, we present formal lemmas and theorems to ensure correctness and define theoretical bounds on forgery resistance. Although Falcon-M does not rely on a formal cryptographic trapdoor, we demonstrate that it achieves strong practical security based on assumptions related to the Short Integer Solution (SIS) problem. Falcon-M is thus well-suited for lightweight post-quantum applications, particularly in resource-constrained environments, such as embedded systems and Internet-of-Things (IoT) platforms. Full article

Quantum mechanics (QM) revolutionizes drug discovery by providing precise molecular insights unattainable with classical methods. This review explores QM’s role in computational drug design, detailing key methods like density functional theory (DFT), Hartree–Fock (HF), quantum mechanics/molecular mechanics (QM/MM), and fragment molecular orbital (FMO). These methods model electronic structures, binding affinities, and reaction mechanisms, enhancing structure-based and fragment-based drug design. This article highlights the applicability of QM to various drug classes, including small-molecule kinase inhibitors, metalloenzyme inhibitors, covalent inhibitors, and fragment-based leads. Quantum computing’s potential to accelerate quantum mechanical (QM) calculations is discussed alongside novel applications in biological drugs (e.g., gene therapies, monoclonal antibodies, biosimilars), protein–receptor dynamics, and new therapeutic indications. A molecular dynamics (MD) simulation exercise is included to teach QM/MM applications. Future projections for 2030–2035 emphasize QM’s transformative impact on personalized medicine and undruggable targets. The qualifications and tools required for researchers, including advanced degrees, programming skills, and software such as Gaussian and Qiskit, are outlined, along with sources for training and resources. Specific publications on quantum mechanics (QM) in drug discovery relevant to QM and molecular dynamics (MD) studies are incorporated. Challenges, such as computational cost and expertise requirements, are addressed, offering a roadmap for educators and researchers to leverage quantum mechanics (QM) and molecular dynamics (MD) in drug discovery. Full article

The essence of coal spontaneous combustion lies in the existence of a large number of chemically active functional groups in the coal molecule, such as aldehyde group (-CHO) and methoxy group (-OCH₃) in the side chain structure of coal molecule, which can be easily oxidized, thus triggering the spontaneous combustion process. Retardant is a more widely used technology to prevent the spontaneous combustion of coal, but the research on the microscopic level of the mechanism of coal spontaneous combustion retardation has been weak for many years, so deepening the exploration in this field is crucial for the optimization of the retardation strategy. The inhibition effect of Li⁺, Na⁺, and K⁺ inhibitors was investigated through the programmed warming experiments, and the results showed that the carbon monoxide production and oxygen consumption of coal samples inhibited by Li⁺, Na⁺, and K⁺ inhibitors were reduced to different degrees compared with that of the original coal, which proved that it had an inhibitory effect on the spontaneous combustion of coal. In order to deeply investigate the interaction between the molecular structure properties of coal and alkali metal ions, the complexes formed by three typical alkali metal ions-Li⁺, Na⁺, and K⁺-with specific reactive groups (-CHO and -OCH₃) in coal were investigated with the help of the quantum chemical calculation software Gaussian 16W, and the following conclusions were made after analyzing the complexes: on the one hand, the complexes formed by Li⁺, Na⁺, and K⁺ with the reactive groups in coal can occupy the sites where the reactive groups bind with oxygen, reduce the chance of coal oxygen contact and inhibit its oxidation process; on the other hand, the coordinating action of alkali metal ions increases the maximum energy barrier that needs to be overcome for the reaction of the originally active groups, resulting in the coal molecules in the process of oxidation reaction, increasing the difficulty of the reaction, thus effectively curbing the tendency of spontaneous combustion of coal. Full article

Partially nonlocal (PNL) variable-coefficient nonlinear Schrödinger equations (NLSEs) represent a significant area of study in mathematical physics and quantum mechanics, particularly in scenarios where potential and coefficients vary spatially or temporally. The (3+1)-dimensional partially nonlocal (PNL) coupled nonlinear Schrödinger (NLS) model, enriched with different values of two transverse diffraction profiles and subjected to gain or loss phenomena, undergoes dimensional reduction to a (2+1)-dimensional counterpart model, facilitated by a conversion relation. This reduction unveils intriguing insights into the excited mechanisms underlying partially nonlocal waves, culminating in analytical solutions that describe high-dimensional extreme waves characterized by Hermite–Gaussian envelopes. This paper explores novel extreme wave solutions in (3+1)-dimensional PNL systems, employing Hirota’s bilinearization method to derive analytical solutions for ring-like bright–bright vector two-component one-soliton solutions. This study examines the dynamic evolution of these solutions under varying dispersion and nonlinearity conditions and investigates the impact of gain and loss on their behavior. Furthermore, the shape of the obtained solitons is determined by the parameters s and q, while the Hermite parameters p and n modulate the formation of additional layers along the z-axis, represented by $p+1$ and $n+1$, respectively. Our findings address existing gaps in understanding extreme waves in partially nonlocal media and offer insights into managing these phenomena in practical systems, such as optical fibers. The results contribute to the theoretical framework of high-dimensional wave phenomena and provide a foundation for future research in wave dynamics and energy management in complex media. Full article

During this study, a molecular system was modeled: a nimesulide, β-cyclodextrin, inclusion complex. The use of the Gaussian 16W software package allowed us to optimize geometry and determine the thermochemical characteristics of molecular systems without considering a solvent. And this was also carried out in water media, accounted for by the polarized continuum model (PCM). To confirm the accuracy of the geometry of the β-cyclodextrin molecule, a structural alignment of 46 β-cyclodextrin molecules, accessible by a corresponding search query in the RCSB database, was performed. The RSMD values of carbon and oxygen atom deviations, as well as the total number of atoms aligned, were calculated. This calculation showed a complete conformational coincidence between the β-cyclodextrin structure designed by us and the RCSB database structures. This ensures the correct approach to subsequent calculations involving this structure. Quantum-mechanical modeling of the relationship was carried out in several stages with a gradual complexity of the basic set. The hybrid method of functional density B3LYP and 6-31G(d) was used. At the end of the calculation stage, on the surface of the studied complex, the potential energy of several minimal elements was detected. This means that there are several conformational forms of the molecular system with likely differences. The change in potential energies of the investigated compounds, caused by their application to optimize the in vacuum molecules of the PCM, allowed us to determine the values of the solvatization energies. The greater magnitude of these values in the complex under consideration indicates its better solubility in water compared to nimesulide. Full article

The cooling of a macroscopic mechanical oscillator to its quantum ground state is an important step for achieving coherent control over mechanical quantum states. Here, we theoretically study the cooling of a rotating mirror in a Laguerre–Gaussian (L-G) cavity optorotational system with a nonlinear cross-Kerr (CK) interaction. We discuss the effects of the nonlinear CK coupling strength, the cavity detuning, the power of the input Gaussian beam, the topological charge (TC) of the L-G cavity mode, the mass of the rotating mirror, and the cavity length on the cooling of the rotating mirror. We find that it is only possible to realize the improvement in the cooling of the rotating mirror by the nonlinear CK interaction when the cavity detuning is less than the mechanical frequency. Compared to the case without the nonlinear CK interaction, we find that the cooling of the rotating mirror can be improved by the nonlinear CK interaction at lower laser powers, smaller TCs of the L-G cavity mode, larger masses of a rotating mirror, and longer optorotational cavities. We show that the cooling of the rotating mirror can be enhanced by the nonlinear CK interaction by a factor of about 23.3 compared to that without the nonlinear CK interaction. Full article

Molecular imprinting is a promising approach for developing polymeric materials as artificial receptors. However, only a few types of molecularly imprinted polymers (MIPs) are commercially available, and most research on MIP_S is still in the experimental phase. The significant limitation has been a challenge for screening imprinting systems, particularly for weak functional target molecules. Herein, a combined method of quantum mechanics (QM) computations and molecular dynamics (MD) simulations was employed to screen an appropriate 2,4-dichlorophenoxyacetic acid (2,4-D) imprinting system. QM calculations were performed using the Gaussian 09 software. MD simulations were conducted using the Gromacs2018.8 software suite. The QM computation results were consistent with those of the MD simulations. In the MD simulations, a realistic model of the ‘actual’ pre-polymerisation mixture was obtained by introducing numerous components in the simulations to thoroughly investigate all non-covalent interactions during imprinting. This study systematically examined MIP systems using computer simulations and established a theoretical prediction model for the affinity and selectivity of MIPs. The combined method of QM computations and MD simulations provides a robust foundation for the rational design of MIPs. Full article

Aiming at the removal of radioactive cobalt ions from water by graphene oxide (GO), the adsorption mechanism of Co²⁺ on graphene oxide was analyzed using the quantum chemical calculation software Gaussian 16 based on density functional theory. The influence of material structure factors such as carboxyl groups, hydroxyl groups, epoxy groups and graphene sheets as well as external environmental factors such as pH, temperature and interfering ions on the adsorption effect was determined, and the influence of external environment was verified through experiments. Through calculation and experiment, it was found that the existence of oxygen-containing functional groups on graphene oxide can improve the adsorption efficiency of the material appropriately, and increasing the pH under acidic conditions was also helpful to improve the adsorption effect. The material had certain selectivity for Co²⁺, and the adsorption capacity and selectivity could be further improved when it was modified by increasing hydroxyl groups. Full article

The Internet of Things (IoT) plays an essential role in people’s daily lives, such as healthcare, home, traffic, industry, and so on. With the increase in IoT devices, there emerge many security issues of data loss, privacy leakage, and information temper in IoT network applications. Even with the development of quantum computing, most current information systems are weak to quantum attacks with traditional cryptographic algorithms. This paper first establishes a general security model for these IoT network applications, which comprises the blockchain and a post-quantum secure identity-based signature (PQ-IDS) scheme. This model divides these IoT networks into three layers: perceptual, network, and application, which can protect data security and user privacy in the whole data-sharing process. The proposed PQ-IDS scheme is based on lattice cryptography. Bimodal Gaussian distribution and the discrete Gaussian sample algorithm are applied to construct the fundamental difficulty problem of lattice assumption. This assumption can help resist the quantum attack for information exchange among IoT devices. Meanwhile, the signature mechanism with IoT devices’ identity can guarantee non-repudiation of information signatures. Then, the security proof shows that the proposed PQ-IDS can obtain the security properties of unforgeability, non-repudiation, and non-transferability. The efficiency comparisons and performance evaluations show that the proposed PQ-IDS has good efficiency and practice in IoT network applications. Full article

In information transfer, the dissipation of a signal is of crucial importance. The feasibility of reconstructing the distorted signal depends on the related permanent loss. Therefore, understanding the quantized dissipative transversal mechanical waves might result in deep insights. In particular, it may be valid on the nanoscale in the case of signal distortion, loss, or even restoration. Based on the description of the damped quantum oscillator, we generalize the canonical quantization procedure for the case of the transversal waves. Then, we deduce the related damped wave equation and the state function. We point out the two possible solutions of the propagating-damping wave equation. One involves the well-known Gaussian spreading solution superposed with the damping oscillation, in which the loss of information is complete. The other is the Airy function solution, which is non-spreading–propagating, so the information loss is only due to oscillation damping. However, the structure of the wave shape remains unchanged for the latter. Consequently, this fact may allow signal reconstruction, resulting in the capability of restoring the lost information. Full article

The vibrational and electronic properties of several basic radiation defects in potassium bromide are computed at the quantum mechanical level using a periodic supercell approach based on hybrid functionals, an all-electron Gaussian-type basis set, and the Crystalcomputer code. The exciton energy in alkali halides is sufficient to create lattice defects, such as F–H Frenkel defect pairs, resulting in a relatively high concentration of single defects and their complexes. Here, we consider eight defects: the electronic ${\mathrm{F}}^{+}$- and F-centers (bromine vacancy without and with trapped electrons) and their dimers; hole H-center (neutral bromine atom forming the dumbbell ion with a regular ${\mathrm{B}\mathrm{r}}^{-}$ ion.); ${\mathrm{V}}_K$-center (${\mathrm{B}\mathrm{r}}_2^{-}$ molecular ion consisting of a hole and two regular ions); and two complex ${\mathrm{B}\mathrm{r}}_3^{-}$ defects, combinations of several simple defects. The local geometry and the charge- and spin-density distributions of all defects are analyzed. Every defect shows its characteristic features in Raman spectra, and their comparison with available experimental data is discussed. Full article

In certain problems in model building and Bayesian analysis, the results end up in forms connected with generalized zeta functions. This necessitates the introduction of an extended form of the generalized zeta function. Such an extended form of the zeta function is introduced in this paper. In model building situations and in various types of applications in physical, biological and social sciences and engineering, a basic model taken is the Gaussian model in the univariate, multivariate and matrix-variate situations. A real scalar variable logistic model behaves like a Gaussian model but with a thicker tail. Hence, for many of industrial applications, a logistic model is preferred to a Gaussian model. When we study the properties of a logistic model in the multivariate and matrix-variate cases, in the real and complex domains, invariably the problem ends up in the extended zeta function defined in this paper. Several such extended logistic models are considered. It is also found that certain Bayesian considerations also end up in the extended zeta function introduced in this paper. Several such Bayesian models in the multivariate and matrix-variate cases in the real and complex domains are discussed. It is stated in a recent paper that “Quantum Mechanics is just the Bayesian theory generalized to the complex Hilbert space”. Hence, the models developed in this paper are expected to have applications in quantum mechanics, communication theory, physics, statistics and related areas. Full article

Vortex beams with helical phase wavefronts have recently emerged as a research hotspot because of their widespread applications such as ultra-high dimensional information encoding, quantum entanglement, and data transmission due to their unique properties. Research, as of yet, on the easy preparation of vector vortex beams is hindered by technical bottlenecks such as large mechanical modulation errors and limited bandwidths of meta-structured devices in spite of the massive experimental and theoretical breakthroughs in the generation of vortex beams that have been made. To make up for the deficiency in this area, we propose here a broadband vortex beam modulating system based on electrically controlled liquid crystal (LC) devices. An electrically controlled LC q-plate and an LC broadband polarization grating (PG) are integrated in the system as the crux devices. The system enables pure vortex-phase modulation within a wide spectral range in the visible spectrum and electrical control on the output beam intensity of the vortex and Gaussian components. Experiments at different voltages of 533 nm and 632.8 nm were conducted for validation. This system overcomes the complexity and stringent optical path requirements of traditional methods for generating vortex beams, offering an efficient, convenient, and rapidly tunable approach for generating vortex beams that is easily and highly integrable. Full article

Quantum entanglement will play an important role in future quantum technologies. Here, we theoretically study the steady-state entanglement between a cavity field and a macroscopic rotating mirror in a Laguerre–Gaussian-(LG)-cavity optomechanical system with cross-Kerr nonlinearity. Logarithmic negativity is used to quantify the steady-state entanglement between the cavity and mechanical modes. We analyze the impacts of the cross-Kerr coupling strength, the cavity detuning, the input laser power, the topological charge of the LG-cavity mode, and the temperature of the environment on the steady-state optomechanical entanglement. We find that cross-Kerr nonlinearity can significantly enhance steady-state optomechanical entanglement and make steady-state optomechanical entanglement more robust against the temperature of the thermal environment. Full article

Quantum entanglement in macroscopic systems plays an important role in quantum information processing. Here, we show that the steady-state entanglement between the two cavity modes in the macroscopic Laguerre–Gaussian (L–G) cavity optorotating system can be enhanced by placing a degenerate optical parametric amplifier (OPA) inside the cavity. The two L–G cavity modes are coupled to the same rotating mirror and are respectively driven at the red and blue mechanical sidebands. We use the logarithmic negativity to quantify the steady-state entanglement between the two cavity modes. We study the influences of the nonlinear gain and phase of the OPA, the temperature of the environment, and the angular momentums of the two cavity modes on the entanglement between the two cavity modes. In the cryogenic environment temperatures, when the angular momentums of the two cavity modes are identical, the enhancement of the entanglement between the two cavity modes by the OPA is the most significant. Full article