In order to enhance the effectiveness of the quantum genetic algorithm (QGA), it is proposed to switch to higher-order quantum registers in the quantum chromosome representation. Such representation makes it possible to apply a powerful quantum computations mechanism – quantum state entanglement. In the algorithm implementation, we also use an adaptive quantum gate operator and propose a quantum chromosome recovery technology for solving constrained combinatorial optimization problems. The influence of the quantum register size on the algorithm efficiency has been investigated. The advantages of the suggested approach in comparison with the QGA traditional implementation are demonstrated on the example of multidimensional 0–1 knapsack problem and different levels of input data correlation.
In order to enhance the effectiveness of the quantum genetic algorithm (QGA), it is proposed to switch to higher-order quantum registers in the quantum chromosome representation. Such representation makes it possible to apply a powerful quantum computations mechanism – quantum state entanglement. In the algorithm implementation, we also use an adaptive quantum gate operator and propose a quantum chromosome recovery technology for solving constrained combinatorial optimization problems. The influence of the quantum register size on the algorithm efficiency has been investigated. The advantages of the suggested approach in comparison with the QGA traditional implementation are demonstrated on the example of multidimensional 0–1 knapsack problem and different levels of input data correlation.
Quantum Genetic Algorithm (QGA) has a number of advantages in comparison with its classical version: operating speed, small population size and auto-balance between the global search and the local search. It is based on the ideas of traditional evolutionary algorithms, applied to the quantum computations technology, which operate with quantum bits, superposition of states and quantum measurements. This paper proposes a QGA with a new adaptive quantum gate operator and a restoring technology for the quantum chromosome during the process of solving combinatorial problems with constraints. Meta-optimization of the primary algorithm parameters is used for providing the algorithm efficiency. The productiveness of the suggested approach is proven by the model studies, carried out using a wide range of test 0–1 knapsack problems.
Quantum genetic algorithms(QGA) typically construct traditional quantum chromosomes as independent quantum bit systems, which has facilitated the enhancement of search speed and precision in genetic algorithms, demonstrating powerful problem-solving capabilities in optimization issues. Although traditional QGA have enriched population diversity, they still tend to fall into local optima, and the evolutionary update operations require rotation directions to be determined by lookup tables, a process involving multiple conditional judgments that affect algorithm efficiency. To address these issues, an improved method has been proposed to further enhance the performance of QGA. In the initial population selection, a population grouping evolution method based on microhabitat coevolution strategy is used to prevent the algorithm from getting trapped in local optima when solving complex function problems. Additionally, quantum entanglement is introduced on top of quantum super-position by implementing quantum entanglement using quantum registers, and higher-order quantum rotation gates are employed that do not involve multiple conditional judgments of lookup tables, thus improving the efficiency of quantum chromosome measurement and evolutionary updates. Finally, traditional QGA and higher-order quantum genetic algorithms were applied to test functions in multiple experiments. The results indicate that, compared to traditional QGA, the higher-order quantum genetic algorithms have achieved an increase in convergence speed, an approximate 14.3% improvement in convergence precision, and possess enhanced global search capabilities.
Based on quantum mutation, a quantum genetic algorithm (QGA) to solve combinatorial optimization problem is proposed.It has good features of genetic quantum algorithm (GQA) and traditional genetic algorithm,which can obtain the best solution with one chromosome in a short time.Comparing experiments have been conducted on a typical combinatorial optimization problem——0/1 knapsack problem.Experimental results have shown that the proposed quantum genetic algorithm is superior to genetic quantum algorithm and traditional genetic algorithm on performance.
Based on quantum genetic algorithm(QGA),a novel improved quantum genetic algorithm(NIQGA)to solve combinatorial optimization problem is proposed.To make full use of interference and entanglement characteristics of quantum state,dynamic step length in adjustment of angle of quantum gate,quantum crossover operation and quantum mutation operation are introduced,therefore high efficiency for optimization is achieved.Two typical combinatorial optimization problems—0/1 knapsack problem and route selection problem,are adopted to confirm the performance of NIQGA.Experimental results show that compared with GA and QGA,NIQGA is characterized by fast convergence rate and excellent capability on global optimization,especially better performance for combinatorial optimization problem with less correlation of genes.
Abstract Quantum Genetic Algorithms (QGAs) integrate genetic programming and quantum computing to address search and optimization problems. Most QGA approaches add quantum features to genetic algorithm operators, such as selection, crossover, or mutation. Oppositely, the Reduced Quantum Genetic Algorithm (RQGA) is a fully quantum algorithm that encodes the entire search space (i.e., population) as a superposition of all possible solutions (chromosomes) using the individuals’ quantum register; the fitness function takes the individuals’ quantum register as input to generate corresponding fitness values within the chromosomes’ superposition. RQGA finds the best fitness value and its corresponding chromosome (i.e., the solution or one of the solutions) using Grover’s algorithm. The complexity of Grover’s algorithm is O(2N⁄2), where N is the number of superposed individual chromosomes. However, RQGA operates on an exponentially-big search space (N = 2n, where n is the number of qubits in the individuals’ quantum register), which entails an exponential runtime of O(2n⁄2). This paper introduces an optimization solution for RQGA that controls the algorithm complexity by selecting a limited number of qubits in the individuals’ register and fixing the remaining ones as classical values of ’0’ and ’1’ with a genetic algorithm. We also improve the performance of the RQGA by discarding unfit solutions and bounding the search only in the valid individuals’ area. Putting it all together, we introduce a novel quantum genetic algorithm—Hybrid Quantum Algorithm with Genetic Optimization (HQAGO)—that solves search problems in O(2(n-k)⁄2) oracle queries, where k is the number of fixed classical bits in the individuals’ register. We illustrate instantiations of HQAGO that solve the NP-hard knapsack and graph coloring problems, analyze the complexity of the new algorithm, and study the convergence of its heuristic part.
This paper proposes a novel evolutionary computing method called a genetic quantum algorithm (GQA). GQA is based on the concept and principles of quantum computing such as qubits and superposition of states. Instead of binary, numeric, or symbolic representation, by adopting qubit chromosome as a representation GQA can represent a linear superposition of solutions due to its probabilistic representation. As genetic operators, quantum gates are employed for the search of the best solution. Rapid convergence and good global search capability characterize the performance of GQA. The effectiveness and the applicability of GQA are demonstrated by experimental results on the knapsack problem, which is a well-known combinatorial optimization problem. The results show that GQA is superior to other genetic algorithms using penalty functions, repair methods and decoders.