Search Results (63)

Multiplication is a fundamental operation in digital signal processing, embedded computing, and nanoscale arithmetic data paths, where area, delay, and energy efficiency are critical design constraints. However, nanoscale multiplier design is challenged by high interconnect complexity, frequent wire crossings, clock-zone synchronization issues, and the rapid growth of area and latency with operand size. Quantum-dot cellular automata (QCA) technology offers a promising post-CMOS platform for compact arithmetic circuit realization through field-coupled computation and transistor-free switching. This paper presents a single-layer QCA-based Dadda Tree Multiplier (DTM) using layout-aware integration of compact half-adder, full adder, XOR, and carry-skip adder modules. The proposed design emphasizes partial-product compression, routing compactness, clock-aware organization, and area-efficient final accumulation. Functional verification is performed using QCADesigner 2.0.3, while energy-related behavior is evaluated using QCADesigner-E under the conventional QCA simulation framework. The proposed DTM consists of 4282 cells and occupies 6.14 μm². Compared with a recent compact QCA multiplier baseline, the proposed architecture reduces cell count by 59.12% and occupies area by 39.80%, while maintaining competitive clocking latency. These results indicate that layout-aware integration of arithmetic modules can substantially improve the area efficiency of QCA-based multipliers, making the proposed design a compact arithmetic core for future nanoscale embedded and signal-processing systems. Full article

Edge Internet of Things (IoT) blockchain deployments increasingly rely on continuous transaction ingestion from resource-constrained IoT devices to nearby edge gateways over heterogeneous wireless links. In this setting, transient channel noise and packet corruption can inject invalid payloads into the edge processing pipeline and trigger unnecessary buffering, parsing, and, most critically, computationally expensive cryptographic operations such as digital signature verification. This leads to wasted computation, increased latency, and reduced energy efficiency at the edge, particularly under dense IoT traffic. This paper presents an energy-aware and fault-tolerant Quantum-Dot Cellular Automata (QCA)-based integrity pre-filter for IoT-to-edge blockchain transaction ingestion. At the circuit level, we adapt and modify a previously reported fault-tolerant five-input majority gate (MV5) structure and use it as a robust primitive for nanoscale integrity-screening circuits. Building on this modified MV5, we design a set of QCA integrity blocks, including a parity checker, a compact XNOR gate circuit, a parity-bit generation circuit, and a sender-to-channel/receiver nano-communication integrity workflow suitable for early screening of corrupted payloads. Compared with the best previously reported baseline considered in this study, the modified MV5 achieves 76.47% tolerance to single-cell omission defects, corresponding to a 17.47 percentage-point increase and an approximately 29.61% relative improvement over the prior 59% omission-tolerance result, while preserving 100% tolerance against extra-cell deposition defects. At the system level, the proposed circuit is discussed as a potential early screening stage for edge-IoT blockchain transaction ingestion. A bounded analytical model is used to estimate the possible reduction in unnecessary signature-verification workload under assumed corruption and detection conditions. This analysis is not intended as a deployment-level validation; full edge-node implementation, throughput measurement, queueing-delay evaluation, real traffic traces, retransmission behavior, and empirical signature-verification profiling remain future work. The proposed parity/chunk-parity pre-filter is designed for low-cost detection of random transmission-induced corruption and does not replace cryptographic authentication, hashing, digital signatures, CRC-based detection, or blockchain validation. All proposed designs are validated using QCADesigner tools. Full article

Internet of Things (IoT) nodes continuously acquire, buffer, and transmit sensor data under strict constraints on area, latency, and energy consumption. However, conventional complementary metal–oxide–semiconductor (CMOS)-based memory-access circuits face increasing power loss, parasitic effects, interconnect complexity, and sensitivity to process variations at the nanoscale. To address these limitations, this paper proposes a quantum-dot cellular automata (QCA)-based decoder-driven static random-access memory (SRAM)-access architecture for compact and energy-efficient IoT perception-layer memory. The proposed framework integrates three main components: a majority-logic RAM cell with feedback-based storage and non-destructive readout, a compact 2 × 4 decoder with enable and auxiliary asynchronous set/reset control, and a 1 × 4 SRAM array in which the decoder is embedded to reduce routing and clocking overhead. The circuit layouts were implemented and functionally verified using QCADesigner 2.0.3, while the energy behavior was evaluated using QCADesigner-E. Simulation results confirm correct write/read (W/R) and address-selection behavior. The proposed 2 × 4 decoder achieves 86 QCA cells, 0.08 µm² occupied area, and one clocking unit, reducing cell count, area, and clocking by 48.19%, 50.00%, and 20.00%, respectively, compared with the best selected decoder baseline. The integrated 1 × 4 SRAM array achieves 684 cells and 14 clocking units, improving timing by 30.00% compared with the closest SRAM-array baseline. These results demonstrate that the proposed QCA-based memory-access structure provides a compact and low-overhead solution for energy-constrained IoT communication systems. Full article

We formulate the Quantum Information Copy Time (QICT) framework for conserved charges under strictly local quantum dynamics and isolate its logically strongest consequence. The theorem-level core is a receiver-optimised variational speed-limit inequality: after projection away from the conserved zero mode, the copy time is bounded from below by the inverse square root of a Liouvillian-squared receiver susceptibility times a local encoding seminorm. This statement is written in a finite-volume operator framework and does not require a diffusive ansatz. We then examine what follows only after additional infrared assumptions. Under a single diffusive slow-mode hypothesis, the variational inequality reduces to the practical scaling relation used in the benchmark computations. That reduction is treated as conditional and is stress-tested numerically rather than promoted by rhetoric. Within the anomaly-free Abelian span relevant for one Standard-Model-like generation, hypercharge selection is elevated to theorem-level status; by contrast, minimal gauge-algebra uniqueness remains explicitly conditional on additional model-selection axioms. The remainder of the manuscript is organised as an explicitly documented closure programme built on top of this core. In that closure, a gauge-coded QCA construction, a microscopic benchmark for the transport normalisation, and an electroweak matching convention are combined to produce a resonance-centred Higgs-portal singlet-scalar mass band together with direct-detection, invisible-width, and relic-consistency checks. These latter results are presented as model-dependent consequences of an explicit closure ansatz rather than as deductions from locality alone. Full article

Rapid urbanization has transformed the face of Texas by converting agricultural and natural lands into expanding built-up areas. This study analyzes and simulates land-use and land-cover (LULC) changes in Kaufman County, Texas, one of the fastest-growing counties in the United States, using a hybrid Cellular Automata–Artificial Neural Network (CA–ANN) model within the Quantum Geographic Information System (QGIS) Modules for Land-Use Change Evaluation (MOLUSCE) framework. Multitemporal NLCD datasets (2001, 2011, and 2021) and six spatial drivers: Elevation, Slope, Aspect, Distance from Roads and Rivers, and Built-up Density were used in the modeling framework. Transition relationships were calibrated using the 2001–2011 LULC data, and the model was validated by simulating the 2021 LULC map from the 2011 baseline. The calibrated model was then used to simulate future LULC scenarios for 2031, 2041, and 2051. Model validation yielded an overall Kappa value of 0.84 and a correctness of 90.9%, indicating high similarity between the observed and simulated maps. The results indicate simulated urban expansion, with built-up areas increasing by nearly 30% by 2051 at the expense of cropland and open areas, with forest and water bodies slightly increasing, and wetlands remaining stagnant. The CA–ANN model effectively captured the nonlinear, spatially dependent land-transition patterns using open-source tools. These findings provided useful information for sustainable land-use planning and environmental management, with the potential to incorporate spatial modeling into regional development strategies in rapidly urbanizing areas of Texas. Full article

Quantum-dot Cellular Automata (QCA) technology has emerged as a promising approach for constructing nanoscale digital circuits, offering notable advantages such as minimal power consumption, rapid processing speeds, and highly compact layouts. Traditional CMOS technology faces significant challenges at the nanoscale, including reduced gate control and increased current leakage. QCA, on the other hand, provides a robust platform for building next-generation digital systems. In this study, a unique single-layer QCA-based Full-Adder (QCAFA) and Carry-Save Adder (CSA) architecture is developed to enhance key performance factors such as delay, space, cost, and cell block count. The outlined designs demonstrate superior efficiency compared to state-of-the-art single-layer and multilayer QCA designs. Simulation results conducted with QCADesigner 2.0.3 and QCADesigner-E reveal that the proposed architecture achieves a substantial 34.29% diminution in total cells compared with the recent design, utilising only 46 QCA cells. Similarly, for the CSA, the proposed design attains an 18.62% reduction in cell count compared with its best counterpart, utilising only 424 QCA cell blocks. To enhance design credibility and hardware relevance, this research additionally models and validates the architecture using the Verilog hardware description language (HDL Version 12.0), thereby bridging the gap between nano-architecture and HDL-based prototyping. Simulation results obtained through QCADesigner confirm the correctness and stability of the QCA layout, while HDL simulation verifies functional equivalence at the behavioural and structural levels. The proposed designs not only enhance speed and reduce energy consumption but also offer better manufacturability. The findings of this study highlight the potential of QCA technology as a feasible substitute for CMOS for high-performance digital arithmetic circuits at the nanoscale. Full article

Molecular quantum-dot cellular automata (QCA) are attracting much attention as an alternative that can improve the problems of digital circuit design technology represented by existing CMOS technology. In particular, they are well suited to the upcoming nanoquantum environment era with their small size, fast switching speed, and low power consumption. In this study, we propose a 5 × 5 × 1 ultra-slim vertical panel type multi-layer 2-to-1 multiplexer (Mux) using molecular QCA, departing from conventional multi-layer formats, and show its expansion to 4-to-1 Mux and application to vertical panel type D-latch and RAM cells. In addition, the polarization phenomenon of cells is physically proven using the potential energy, distance among electrons, and the relative positions of cells, and the secure RAM design takes noise elimination and polarization of the output signal into consideration. The circuits are simulated in terms of operation and performance using QCADesigner 2.0.3 and QCADesignerE, and the proposed multi-layer 2-to-1 Mux shows a significant improvement of at least 1473% and 277% in two representative standard design costs compared to the state-of-the-art multi-layer Muxes. Full article

One of the nanoscale technologies that shows its capability of implementing integrated digital circuits with low power, high speed, and high density is quantum-dot cellular automata (QCA). The fundamental device for designing and implementing circuits in QCA is majority logic. In this paper, a novel energy-efficient QCA design of three-input AND/OR logic functions is proposed. This design can perform both AND and OR logic operations using the same structure with an achievement of 58% and 64% approximate reductions in power consumption compared to majority-based structures, and 31% and 32% approximate reductions in power consumption compared to the best available circuits, respectively. In addition, other physical constraints such as area and latency are improved and have better or similar results compared to the best existing circuits. The proposed circuit can be considered as a fundamental and better alternative to the majority gate for energy-efficient circuit design in QCA. This will pave the way for developing efficient large-scale QCA-based sequential and combinational circuits. Full article

Mutually unbiased bases (MUBs) are essential tools in quantum information science, with applications in state tomography, quantum cryptography, and quantum error correction. In this work, we introduce a constructive framework for generating MUBs using linear bipermutive cellular automata (LBCAs). By leveraging the algebraic structure of generalized Pauli operators over finite fields, we show that disjoint families of LBCAs correspond to commuting sets of such operators (CSPOs), which, in turn, generate MUBs. This correspondence enables the systematic construction of complete or incomplete sets of MUBs, depending on the number of disjoint LBCAs available in a given dimension. We also provide algebraic conditions to verify disjointness and discuss how the finite dimensionality constrains MUB completeness. Our approach reinterprets classical combinatorial structures in a quantum setting, offering new computational pathways for exploring MUBs through discrete dynamical systems. Full article

Quantum-dot cellular automata (QCA) offer a high-performance, low-power alternative to traditional VLSI technology for nanocomputing. However, the existing metal-dot QCA-based parity generators and checker circuits suffer from increased energy dissipation, larger area consumption, and complex multilayered layouts, limiting their practical feasibility. This work designs a 3-bit parity generator and 4-bit checker to address these challenges using an optimized modified majority voter-based Ex-OR gate in QCA. A single-layered layout was simulated in QCADesigner 2.0.3, avoiding crossovers to reduce fabrication complexity. Energy analysis using QCADesigner-E reveals 34.4 meV energy consumption, achieving 31% energy efficiency and 75% area efficiency in the context of QCA costs compared to recent designs. The proposed circuit highlights the unique potential of QCA as a scalable, energy-efficient solution for high-density next-generation computing systems. Full article

Recent work has demonstrated a correspondence that bridges quantum information processing and high-energy physics: discrete quantum cellular automata (QCA) can, in the continuum limit, reproduce quantum field theories (QFTs). This QCA/QFT correspondence raises fundamental questions about how matter/energy, information, and the nature of spacetime are related. Here, we show that free QED is equivalent to the continuous-space-and-time limit of Fermi and Bose QCA theories on the cubic lattice derived from quantum random walks satisfying simple symmetry and unitarity conditions. In doing so, we define the Fermi and Bose theories in a unified manner using the usual fermion internal space and a boson internal space that is six-dimensional. We show that the reduction to a two-dimensional boson internal space (two helicity states arising from spin-1 plus the photon transversality condition) comes from restricting the QCA theory to positive energies. We briefly examine common symmetries of QCAs and how time-reversal symmetry demands the existence of negative-energy solutions. These solutions produce a tension in coupling the Fermi and Bose theories, in which the strong locality of QCAs seems to require a non-zero amplitude to produce negative-energy states, leading to an unphysical cascade of negative-energy particles. However, we show in a 1D model that, by extending interactions over a larger (but finite) range, it is possible to exponentially suppress the production of negative-energy particles to the point where they can be neglected. Full article

The Thirring Quantum Cellular Automaton (QCA) describes the discrete time dynamics of local fermionic modes that evolve according to one step of the Dirac cellular automaton, followed by the most general on-site number-preserving interaction, and serves as the QCA counterpart of the Thirring model in quantum field theory. In this work, we develop perturbative techniques for the QCA path sum approach, expanding both the number of interaction vertices and the mass parameter of the Thirring QCA. By classifying paths within the regimes of very light and very heavy particles, we computed the transition amplitudes in the two- and three-particle sectors to the first few orders. Our investigation into the properties of the Thirring QCA, addressing the combinatorial complexity of the problem, yielded some useful results applicable to the many-particle sector of any on-site number-preserving interactions in one spatial dimension. Full article

The crystalline state of matter serves as a reference point in the context of studies of properties of a variety of chemical compounds. This is due to the fact that prepared crystalline solids of practically useful materials (inorganic or organic) may be utilized for the thorough characterization of important properties such as (among others) energy bandgap, light absorption, thermal and electric conductivity, and magnetic properties. For that reason it is important to develop mathematical descriptions (models) of properties and structures of crystals. They may be used for the interpretation of experimental data and, as well, for predictions of properties of novel, unknown compounds (i.e., the design of novel compounds for practical applications such as photovoltaics, catalysis, electronic devices, etc.). The aim of this article is to review the most important mathematical models of crystal structures and properties that vary, among others, from quantum models (e.g., density functional theory, DFT), through models of discrete mathematics (e.g., cellular automata, CA), to machine learning (e.g., artificial neural networks, ANNs). Full article

The density classification (DC) task, a computation which maps global density information to local density, is studied using one-dimensional non-unitary quantum cellular automata (QCAs). Two approaches are considered: one that preserves the number density and one that performs majority voting. For number-preserving DC, two QCAs are introduced that reach the fixed-point solution in a time scaling quadratically with the system size. One of the QCAs is based on a known classical probabilistic cellular automaton which has been studied in the context of DC. The second is a new quantum model that is designed to demonstrate additional quantum features and is restricted to only two-body interactions. Both can be generated by continuous-time Lindblad dynamics. A third QCA is a hybrid rule defined by both discrete-time and continuous-time three-body interactions that is shown to solve the majority voting problem within a time that scales linearly with the system size. Full article