We present PyQUBO, an open-source Python library for constructing quadratic unconstrained binary optimizations (QUBOs) from the objective functions and the constraints of optimization problems. PyQUBO enables users to prepare QUBOs or Ising models for various combinatorial optimization problems with ease thanks to the abstraction of expressions and the extensibility of the program. QUBOs and Ising models formulated using PyQUBO are solvable by Ising machines, including quantum annealing machines. We introduce the features of PyQUBO with applications in the number partitioning problem, knapsack problem, graph coloring problem, and integer factorization using a binary multiplier. Moreover, we demonstrate how PyQUBO can be applied to production-scale problems through integration with quantum annealing machines. Through its flexibility and ease of use, PyQUBO has the potential to make quantum annealing a more practical tool among researchers.
We present PyQUBO, an open-source Python library for constructing quadratic unconstrained binary optimizations (QUBOs) from the objective functions and the constraints of optimization problems. PyQUBO enables users to prepare QUBOs or Ising models for various combinatorial optimization problems with ease thanks to the abstraction of expressions and the extensibility of the program. QUBOs and Ising models formulated using PyQUBO are solvable by Ising machines, including quantum annealing machines. We introduce the features of PyQUBO with applications in the number partitioning problem, knapsack problem, graph coloring problem, and integer factorization using a binary multiplier. Moreover, we demonstrate how PyQUBO can be applied to production-scale problems through integration with quantum annealing machines. Through its flexibility and ease of use, PyQUBO has the potential to make quantum annealing a more practical tool among researchers.
The Quadratic Unconstrained Binary Optimization (QUBO) model is widely used to solve combinatorial optimization problems by determining the optimal assignment of binary variables in a quadratic formulation. Given its versatility, extensive research has been conducted on developing QUBO solvers and converting combinatorial optimization problems into equivalent QUBO formulations. This paper introduces QUBO++, a novel C++ symbolic mathematical computation library specifically designed for QUBO modeling. It provides a comprehensive set of operators and functions for symbolic computation, enabling seamless transformation of optimization problems into QUBO models. While several Python-based libraries exist for similar purposes, QUBO++ is the only dedicated C++ library that supports multithreaded acceleration via Intel Threading Building Blocks (oneTBB). In addition to its modeling capabilities, QUBO++ includes two fundamental QUBO solvers: the Exhaustive Solver, which is useful for verifying small-scale problems, and the Easy Solver, designed for efficient testing and debugging. Compared to existing Python-based QUBO modeling tools such as PyQUBO, Fixstars Amplify, and Tytan, QUBO++ demonstrates significantly higher performance, achieving speedups of over 1,700 times in certain scenarios. By leveraging QUBO-based problem-solving techniques, QUBO++ serves as a powerful and versatile tool for addressing complex optimization challenges in both industrial and societal applications.
Multidimensional knapsack problem is a classical combinatorial optimization problem, the goal is to find a set of optimal options to satisfy all the constraints. The traditional algorithms for solving multidimensional knapsack problems generally have some disadvantages, such as slow computation speed and exponential increase of computation with the increase of problem dimension. To solve these problems, a QUBO (quadratic unconstrained binary optimization) model is proposed, and the multidimensional knapsack problem is expressed as a quadratic unconstrained binary optimization problem. Binary variables are used to represent the objective function of the multidimensional knapsack problem. The constraints are added to the objective function in the form of quadratic terms by means of penalty terms. The objective function is further transformed into QUBO form. The model is created by PyQUBO, an open source Python library, and solved by quantum annealing algorithm on D-Wave platform. The results show that the QUBO model has a strong ability of mathematical expression, which makes the problem more structured, and is suitable for large-scale problems, dealing with multidimensional knapsack problems with a lot of variables and constraints.
Combinatorial optimization problems are of great significance in many fields, and this paper explores the application of quantum annealing-based QUBO (Quadratic Unconstrained Binary Optimization) model to combinatorial optimization problems, including the 0/1 knapsack problem, the traveler's problem, the maximum cut problem, and the graph coloring problem. The quantum annealing algorithm can effectively avoid falling into local optimal solutions by virtue of its unique quantum tunneling advantage, and shows significant advantages in solving complex combinatorial optimization problems, especially in dealing with large-scale data and multiple constraints, quantum annealing provides an efficient solution.
The Quadratic Unconstrained Binary Optimization (QUBO) model has gained prominence in recent years with the discovery that it unifies a rich variety of combinatorial optimization problems. By its association with the Ising problem in physics, the QUBO model has emerged as an underpinning of the quantum computing area known as quantum annealing and has become a subject of study in neuromorphic computing. Through these connections, QUBO models lie at the heart of experimentation carried out with quantum computers developed by D-Wave Systems and neuromorphic computers developed by IBM. Computational experience is being amassed by both the classical and the quantum computing communities that highlights not only the potential of the QUBO model but also its effectiveness as an alternative to traditional modeling and solution methodologies. This tutorial discloses the basic features of the QUBO model that give it the power and flexibility to encompass the range of applications that have thrust it onto center stage of the optimization field. We show how many different types of constraining relationships arising in practice can be embodied within the "unconstrained" QUBO formulation in a very natural manner using penalty functions, yielding exact model representations in contrast to the approximate representations produced by customary uses of penalty functions. Each step of generating such models is illustrated in detail by simple numerical examples, to highlight the convenience of using QUBO models in numerous settings. We also describe recent innovations for solving QUBO models that offer a fertile avenue for integrating classical and quantum computing and for applying these models in machine learning.
This paper explores the application of Quantum Annealing (QA) to the field of combinatorial optimization. The core idea is to leverage the principles of quantum mechanics, specifically quantum tunneling, to efficiently solve complex optimization problems. We present a framework for utilizing QA to tackle problems represented as quadratic unconstrained binary optimization (QUBO) models. The methodology focuses on mapping the problem's constraints and objective function into a form suitable for QA hardware. We discuss the challenges involved in this mapping process, including the limitations of current QA devices and the need for careful problem formulation. Furthermore, we analyze the potential advantages of QA over classical optimization techniques, particularly concerning the exploration of a wider solution space. The research highlights the promise of QACO as a viable approach for tackling computationally demanding combinatorial optimization tasks, offering a novel method to enhance optimization efficiency.
We present QUBO.jl, an end-to-end Julia package for working with QUBO (Quadratic Unconstrained Binary Optimization) instances. This tool aims to convert a broad range of optimization problems in JuMP, Julia's mathematical programming package, for straightforward application in many physics and physics-inspired solution methods whose standard model form is equivalent to QUBO. These methods include quantum annealing, quantum gate-circuit optimization algorithms (Quantum Optimization Alternating Ansatz, Variational Quantum Eigensolver), other hardware-accelerated platforms, such as Coherent ising machines and Simulated Bifurcation Machines, and more traditional methods such as simulated annealing. In addition to working with reformulations, QUBO.jl allows its users to interface with the aforementioned hardware, sending QUBO models to these devices and retrieving results for subsequent analysis. QUBO.jl was written as a JuMP / MathOptInterface (MOI) layer that automatically maps between the input and output frames, thus providing a smooth modeling experience.