The growing demand in broadband and data networks is a tremendous driver for innovation and investment. Efficient usage of resources and reliable operations are key objectives for network management. Optimization plays a pivotal role to make the best decisions in limited time. To tackle such difficult and elaborate (typically NP-hard) computational problems the latest developments in Quantum Computing are coming into focus. Successes with models for road traffic, logistics or financial industry have already demonstrated the applicability of these new methods to real-world problems. In this paper we formulate a model for resource assignment for transporting data over networks. For applicability in existing network management environments the model was designed on top of Segment Routing (SR) concepts. The validity of the model is proven for different cost and reliability targets. Based on a Digital Annealer (DA) as quantum-inspired hardware and an appropriate decomposition approach realistic data sets of a tier-1 provider can be processed. The quality of the results is comparable to classical optimization methods while the new approaches outperform those in computation time and have potential for a higher number of demands. An end-to-end comparison of quadratic model creation and solving on large data sets versus a processing as linear integer problem is presented. This shows that quantum approaches and algorithms are not only a preparation for a more distant future of fully functional quantum computers but can generate business advantages even today.
The growing demand in broadband and data networks is a tremendous driver for innovation and investment. Efficient usage of resources and reliable operations are key objectives for network management. Optimization plays a pivotal role to make the best decisions in limited time. To tackle such difficult and elaborate (typically NP-hard) computational problems the latest developments in Quantum Computing are coming into focus. Successes with models for road traffic, logistics or financial industry have already demonstrated the applicability of these new methods to real-world problems. In this paper we formulate a model for resource assignment for transporting data over networks. For applicability in existing network management environments the model was designed on top of Segment Routing (SR) concepts. The validity of the model is proven for different cost and reliability targets. Based on a Digital Annealer (DA) as quantum-inspired hardware and an appropriate decomposition approach realistic data sets of a tier-1 provider can be processed. The quality of the results is comparable to classical optimization methods while the new approaches outperform those in computation time and have potential for a higher number of demands. An end-to-end comparison of quadratic model creation and solving on large data sets versus a processing as linear integer problem is presented. This shows that quantum approaches and algorithms are not only a preparation for a more distant future of fully functional quantum computers but can generate business advantages even today.
Routing and wavelength assignment with protection is an important problem in telecommunications. Given an optical network and incoming connection requests, a commonly studied variant of the problem aims to grant a maximum number of requests by assigning lightpaths with minimum network resource usage, while ensuring the provided services remain functional in the case of a single-link failure through dedicated protection paths. We consider a version where alternative lightpaths for requests are assumed to be given as a precomputed set and show that it is NP-hard. We formulate the problem as an Integer Programming (IP) model and also use it as a foundation to develop a Quadratic Unconstrained Binary Optimization (QUBO) model. We present necessary and sufficient conditions on objective function parameters to prioritize request granting objective over wavelength-link usage for both models, and a sufficient condition ensuring the exactness of the QUBO model. Moreover, we implement a problem-specific branch-and-cut algorithm for the IP model and employ a new quantum-inspired technology, Digital Annealer (DA), for the QUBO model. We conduct computational experiments on a large suite of nontrivial instances to assess the efficiency and efficacy of all of these approaches as well as two problem-specific heuristics. Although the objective penalty coefficient values that guarantee the exactness of the QUBO model were outside the acceptable range for DA, it always yielded feasible solutions even with smaller values in practice. The results show that the emerging technology DA outperforms the considered techniques coupled with GUROBI in finding mostly significantly better or as good solutions in two minutes compared to two-hour run time, whereas problem-specific heuristics fail to be competitive.
In planning and scheduling, large-scale optimization problems often have complex limits and a lot of factors, which makes them hard to answer with standard methods. Quantum annealing has become a hopeful way to deal with these problems because it can quickly look into a lot of possible solutions. This essay looks into how quantum annealing might be used to solve optimization problems in transportation and scheduling, with a focus on how it could be used for route planning, inventory management, and arranging workers. To do these optimization jobs, quantum annealing is used. This is a quantum computing method that gets the global minimum of a cost function. We use the D-Wave quantum annealer in this method. It turns the problem's limits and objective function into a quadratic unconstrained binary optimization (QUBO) model. The quantum annealer then works on this model to find the best answers. The suggested method combines traditional preparation methods with quantum annealing to get the best results for big schedule and transportation issues. We use quantum annealing to solve difficult multi-objective optimization problems, like reducing shipping time, cost, and resource use all at the same time. Preliminary results show that quantum annealing can make solutions much better and use computers much more efficiently than traditional methods for optimizing supplies and schedules. Quantum annealing works especially well with problems that have a lot of dimensions. It can provide scalable answers that sometimes work better than standard methods.
Abstract In this work we propose a high-quality decomposition approach for qubit routing by swap insertion. This optimization problem arises in the context of compiling quantum algorithms formulated in the circuit model of computation onto specific quantum hardware. Our approach decomposes the routing problem into an allocation subproblem and a set of token swapping problems. This allows us to tackle the allocation part and the token swapping part separately. Extracting the allocation part from the qubit routing model of Nannicini et al. (Optimal qubit assignment and routing via integer programming, 2021, http://arxiv.org/abs/2106.06446 ), we formulate the allocation subproblem as a binary linear program. Herein, we employ a cost function that is a lower bound on the overall routing problem objective. We strengthen the linear relaxation by novel valid inequalities. For the token swapping part we develop an exact branch-and-bound algorithm. In this context, we improve upon known lower bounds on the token swapping problem. Furthermore, we enhance an existing approximation algorithm which runs much faster than the exact approach and typically is able to determine solutions close to the optimum. We present numerical results for the fully integrated allocation and token swapping problem. Obtained solutions may not be globally optimal due to the decomposition and the usage of an approximation algorithm. However, the solutions are obtained fast and are typically close to optimal. In addition, there is a significant reduction in the number of artificial gates and output circuit depth when compared to various state-of-the-art heuristics. Reducing these figures is crucial for minimizing noise when running quantum algorithms on near-term hardware. As a consequence, using the novel decomposition approach leads to compiled algorithms with improved quality. Indeed, when compiled with the novel routing procedure and executed on real hardware, our experimental results for quantum approximate optimization algorithms show an significant increase in solution quality in comparison to standard routing methods.
Transport network design problem (TNDP) is a well-studied problem for planning and operations of transportation systems. They are widely used to determine links for capacity enhancement, link closures to schedule maintenance, identify new road or transit links and more generally network enhancements under resource constraints. As changes in network capacities result in a redistribution of demand on the network, resulting in changes in the congestion patterns, TNDP is generally modelled as a bi-level problem, which is known to be NP-hard. Meta-heuristic methods, such as Tabu Search Method are relied upon to solve these problems, which have been demonstrated to achieve near optimality in reasonable time. The advent of quantum computing has afforded an opportunity to solve these problems faster. We formulate the TNDP problem as a bi-level problem, with the upper level formulated as a Quadratic Unconstrained Binary Optimization (QUBO) problem that is solved using quantum annealing on a D-Wave quantum computer. We compare the results with Tabu Search. We find that quantum annealing provides significant computational benefit. The proposed solution has implications for networks across different contexts including communications, traffic, industrial operations, electricity, water, broader supply chains and epidemiology.
Quantum computing offers transformative potential to solve complex optimisation problems in transportation and logistics, particularly those that involve large combinatorial decision spaces such as vehicle routing, traffic control, and supply chain design. Despite theoretical promise and growing empirical interest, its adoption remains limited. This systematic literature review synthesises fifteen peer-reviewed studies published between 2015 and 2025, examining the application of quantum and quantum-inspired methods to transport optimisation. The review identifies five key problem domains (vehicle routing, factory scheduling, network design, traffic operations, and energy management) and categorises the quantum techniques used, including quantum annealing, variational circuits, and digital annealers. Although several studies demonstrate performance gains over classical heuristics, most rely on synthetic datasets, lack statistical robustness, and omit critical operational metrics such as energy consumption and queue latency. Four cross-cutting barriers are identified: hardware limitations, data availability, energy inefficiency, and organisational readiness. The review identifies limited real-world deployment, a lack of standardised benchmarks, and scarce cost–benefit evaluations, highlighting key areas where further empirical work is needed. It concludes with a structured research agenda aimed at bridging the gap between laboratory demonstrations and practical implementation, emphasising the need for pilot trials, open datasets, robust experimental protocols, and interdisciplinary collaboration.
Motivated by recent progress in quantum hardware and algorithms, researchers have developed quantum heuristics for optimization problems, aiming for advantages over classical methods. To date, quantum hardware is still error-prone and limited in size such that quantum heuristics cannot be scaled to relevant problem sizes and are often outperformed by their classical counterparts. Moreover, if provably optimal solutions are desired, one has to resort to classical exact methods. As, however, quantum technologies may improve considerably in future, we demonstrate in this work how quantum heuristics with limited resources can be integrated in large-scale exact optimization algorithms for NP-hard problems. To this end, we consider vehicle routing as a prototypical NP-hard problem. We model the pricing and separation subproblems arising in a branch-price-and-cut algorithm as quadratic unconstrained binary optimization problems. This allows to use established quantum heuristics like quantum annealing or the quantum approximate optimization algorithm for their solution. A key feature of our algorithm is that it profits not only from the best solution returned by the quantum heuristic but from all solutions below a certain cost threshold, thereby exploiting the inherent randomness is quantum algorithms. Moreover, we reduce the requirements on quantum hardware since the subproblems, which are solved via quantum heuristics, are smaller than the original problem. We provide a proof-of-concept experimental study comparing quantum annealing to simulated annealing and to established classical algorithms in our framework. While our hybrid quantum-classical approach is still outperformed by purely classical methods, our results reveal that both pricing and separation may be well suited for quantum heuristics if quantum hardware improves.