Quantum computers are increasingly being utilized in various fields such as quantum chemistry, artificial intelligence, and computation. Today's quantum computers also face challenges. Quantum algorithms performed on small quantum computers have high overhead costs. Due to the translation and initialization of algorithms, quantum computers have errors in their calculations that are caused by interference from the environment. Therefore, the results must be checked and any errors corrected. Due to these challenges, quantum computers have recently been linked to classical computers, especially High-Performance Computing systems. This has created a new hybrid quantum system that includes both classical and quantum computers. This bachelor’s thesis is a literature review that examines the different uses of High-Performance Computing in hybrid quantum systems. Applications are divided into three main categories, which include several ways to achieve the same goal. The three groups are: error correction, simulation of quantum computer, and algorithm optimization. The main application of high-performance computing is error correction in the result of a quantum computer. Errors occur when the interference causes decoherence in quantum computer qubits. In this case, they lose the properties of superposition and entanglement. Error correction is an NP-hard problem, with the efficiency requirements of classic machines increasing exponentially with the number of qubits. These requirements cannot be met with ordinary machines, but exceptionally large combinations of machines are needed. High-performance computing is also used to simulate quantum computers. Simulators can perform the same algorithms as quantum computers, but without errors in the results. When classical machines simulate quantum computers, they must keep in memory all the possible states that a quantum machine can have. This sets the memory requirement for a classical machine to O(2n), where n is the number of qubits in a quantum machine. There are various simulator applications that store the states in either a space vector or tensor networks. Tensor-based simulators use less memory than space-based ones. In addition to saving space, different simulators are either made for specific machines or are hardware agnostic. The third application of high-performance computing is the optimization of calculations in hybrid systems. Quantum computers can run optimization algorithms that are exponentially slower on classical machines. However, the quantum algorithms can be enhanced by attaching a classic part, which creates a hybrid solution. These Hybrid Quantum Classical (HQC) algorithms have been used to optimize chemical reaction simulations, database queries and artificial intelligence model training. The high cost and errors of the quantum computers make simulators a more efficient alternative when a small number of qubits is sufficient. For large numbers of qubits, the resource needs of simulators grow exponentially, and they exceed the standard cost of quantum machines.
Quantum computers are increasingly being utilized in various fields such as quantum chemistry, artificial intelligence, and computation. Today's quantum computers also face challenges. Quantum algorithms performed on small quantum computers have high overhead costs. Due to the translation and initialization of algorithms, quantum computers have errors in their calculations that are caused by interference from the environment. Therefore, the results must be checked and any errors corrected. Due to these challenges, quantum computers have recently been linked to classical computers, especially High-Performance Computing systems. This has created a new hybrid quantum system that includes both classical and quantum computers. This bachelor’s thesis is a literature review that examines the different uses of High-Performance Computing in hybrid quantum systems. Applications are divided into three main categories, which include several ways to achieve the same goal. The three groups are: error correction, simulation of quantum computer, and algorithm optimization. The main application of high-performance computing is error correction in the result of a quantum computer. Errors occur when the interference causes decoherence in quantum computer qubits. In this case, they lose the properties of superposition and entanglement. Error correction is an NP-hard problem, with the efficiency requirements of classic machines increasing exponentially with the number of qubits. These requirements cannot be met with ordinary machines, but exceptionally large combinations of machines are needed. High-performance computing is also used to simulate quantum computers. Simulators can perform the same algorithms as quantum computers, but without errors in the results. When classical machines simulate quantum computers, they must keep in memory all the possible states that a quantum machine can have. This sets the memory requirement for a classical machine to O(2n), where n is the number of qubits in a quantum machine. There are various simulator applications that store the states in either a space vector or tensor networks. Tensor-based simulators use less memory than space-based ones. In addition to saving space, different simulators are either made for specific machines or are hardware agnostic. The third application of high-performance computing is the optimization of calculations in hybrid systems. Quantum computers can run optimization algorithms that are exponentially slower on classical machines. However, the quantum algorithms can be enhanced by attaching a classic part, which creates a hybrid solution. These Hybrid Quantum Classical (HQC) algorithms have been used to optimize chemical reaction simulations, database queries and artificial intelligence model training. The high cost and errors of the quantum computers make simulators a more efficient alternative when a small number of qubits is sufficient. For large numbers of qubits, the resource needs of simulators grow exponentially, and they exceed the standard cost of quantum machines.
Hybrid computing models, which integrate both classical and quantum systems, represent a promising frontier in enhancing computational power and efficiency. Classical computing systems, while highly efficient for a broad range of tasks, encounter significant limitations when addressing complex, large-scale problems such as optimization, cryptography, and molecular simulations. Quantum computing, on the other hand, offers exponential speedup for specific algorithms, particularly in areas like factorization, search, and simulation of quantum systems. However, quantum systems are not yet mature enough to replace classical systems entirely, due to issues like error rates, qubit coherence, and the need for cryogenic environments. As a result, hybrid models are emerging as the most viable solution, combining the strengths of both paradigms to tackle computationally intensive tasks more efficiently. This paper provides a comprehensive analysis of the development and application of hybrid computing models. It explores how these models leverage the parallel processing power of quantum systems while utilizing the robustness and data handling capabilities of classical systems. We discuss various architectures proposed for hybrid computing, focusing on their scalability, efficiency, and real-world applications across industries such as healthcare, finance, cryptography, and artificial intelligence. Additionally, we examine the challenges involved in integrating classical and quantum systems, including synchronization, resource management, and algorithm development. The paper concludes with future directions for hybrid computing, emphasizing the potential for these models to revolutionize fields that rely on high-performance computing by offering unprecedented computational capabilities. In summary, hybrid computing models stand at the intersection of classical and quantum technologies, providing a synergistic approach to solving some of the most challenging computational problems faced today.
The entwining of quantum computing with classical machine learning has proven to be one of the most promising frontiers of artificial intelligence, as it possesses the potential to speed up intricate computations in ways that classical systems will never be able to achieve. This study delves into the theoretical and practical implications of hybrid quantum-classical approaches in machine learning, while also examining their advantages, limitations, and applicability in different domains. Utilizing quantum entanglement and parallelism, hybrid solutions also have the potential to process high-dimensional data, optimize complex functions, and facilitate pattern recognition tasks more efficiently. However, noise, decoherence, and limited qubit connectivity on current hardware pose considerable barriers to practical implementations. The authors discuss hybrid architectures like quantum-enhanced optimizers and variational quantum circuits which include classical pre- and post-processing to alleviate quantum limitations. Moreover, a comparative study is performed to show the effectiveness of hybrid models comparing with classical machine learning state-of-the-art in natural language processing, computer vision and financial modeling. Results indicate that although hybrid quantum–classical approaches provide significant gains in optimization and computational efficiency; these benefits remain limited by hardware limitations and the scalability of quantum algorithms. With these considerations in mind, the paper offers guidance for targeting future research directions in quantum machine learning, including advances in quantum error correction, quantum hardware scalability, and new algorithmic approaches. Additional advancements needed and notably, the study focused on a smaller representation of data Since quantum computing is relatively new and researchers are still exploring its application, it is still early days in terms of machine learning models that are solely, intrinsically quantum.
The technology of Quantum Computing (QC) is continuously evolving, as researchers explore new technologies and the public gains access to quantum computers with an increasing number of qubits. In addition, the research community and industry are increasingly interested in the potential use, application, and contribution of QCs to large-scale problems in the real world as a result of this technological enhancement. QCs operations are based on quantum mechanics, and their special properties are mainly exploited to solve computationally intensive problems in polynomial time, problems that are commonly unsolvable, even by High-Performance Computing systems (HPCs) in a feasible time. However, since QCs cannot perform as general-purpose computing machines, alternative computational approaches aiming to boost further their enormous computing abilities are requested, and their combination as an additional computing resource to HPC systems is considered as one of the most promising ones. In the proposed hybrid HPCs, the Quantum Processing Units (QPUs), similar to GPUs and CPUs, target specific problems that, through Quantum Algorithms, can exploit quantum properties like quantum entanglement and superposition to achieve substantial performance gains from the HPC point of view. This interconnection between classical HPC systems and QCs towards the creation of Hybrid Quantum-Classical computing systems is neither straightforward nor standardized while crucial for unlocking the real potential of QCs and achieving real performance improvements. The interconnection between the classical and quantum systems can be performed in the hardware, software (system), or application layer. In this study, a concise overview of the existing architectures for the interconnection interface between HPCs and QCs is provided, focusing mainly on hardware approaches that enable effective hybrid quantum-classical operation.
Abstract: Quantum computing is a new type of computing that uses the principles of quantum physics to perform calculations in ways that are not possible with traditional computers. Unlike classical computers, which process information using bits that are either 0 or 1, quantum computers use quantum bits (qubits) that can exist in multiple states at the same time. This ability allows quantum systems to solve certain complex problems much faster than classical machines. This paper presents a simple and human-centered explanation of quantum computing, focusing on how it works, why it matters, and how it can be applied in real-world situations. The study discusses key concepts such as superposition, entanglement, and quantum gates using easy-to-understand language. It also explores practical applications including cryptography, optimization, drug discovery, and material simulation. In addition, this paper examines the current challenges in quantum computing, such as hardware instability, error correction, limited qubit scalability, and high implementation cost. A conceptual hybrid classical–quantum system model is proposed to show how quantum and classical computers can work together to solve complex problems more efficiently. The goal of this research is to make quantum computing more understandable to students, educators, and decision-makers, and to encourage early awareness and responsible development of this powerful technology. Keywords — quantum computing, qubit, superposition, entanglement, quantum gate, error correction, hybrid computing
Quantum computing aims to outperform classical computers for some specific calculations. It relies on the additional resources given by the qubit superposition states, which can be used to design more efficiently. Reversibility of quantum computation may help in solving NP problems, which are easy in one direction but hard in the opposite sense. Quantum computers can enhance data processing and analysis tasks. The potential impact of quantum algorithms on optimization problems, simulation of quantum systems, and machine learning tasks such as clustering and classification. It also includes efforts to standardize quantum hardware and software interfaces, enabling interoperability and accelerating the adoption of quantum computing. The barriers we face while adopting Quantum computing are the accuracy of the information, lack of technical experts, and organizational interest in adopting the new process. We find one more critical barrier is the lack of standards of secure communication techniques while adopting quantum computing. While numerous challenges lie ahead, the promise of quantum computing in solving complex problems and driving innovation is too significant to ignore. We will examine the existing quantum algorithms and applications that have demonstrated quantum advantage or potential utility in various domains. The quantum computing field is expected to transition from physical qubits to error-corrected logical qubits. AI is likely to be unleashed by quantum computing for formidable progress advances in speed, cost, and algorithm learning function. Quantum computing solves one or two problems, with little practical use, and costs a fortune to run. Additionally, we will assess the challenges associated with scaling up quantum systems, addressing the issues of quantum coherence, error correction, and noise reduction.
This chapter provides a basic overview of Quantum Computers (QCs) used in Quantum Computing (Quacomp) applications. Classical computers utilize silicon-based semiconductor devices. In recent years integrated circuit lateral feature sizes have been reduced to 10 nm, increasing chip density; however, as these sizes progress to be reduced to 5 nm and smaller, silicon-based circuits become impractical. QCs make use of quantum phenomena such as entanglement and superposition to increase and improve the computation speed as compared to classical computers, enabling them to solve some computationally complex problems in practical time windows. At this juncture QCs are not able to act as replacements for general- purpose computers, but they can outperform classical computers in a set of specific computational problems, such as optimization problems or for identifying the best solution from a set of feasible solutions. This chapter covers three QC approaches: the circuit model (or gate model), the adiabatic quantum computation model, and the categorical quantum model. Quacomp has experienced relatively rapid development in recent years, starting with the basic ideation in the early 1980s, then continuing with early proof of concepts for hardware in the next two decades, and now, in the 2020s, with QC hardware that can implement over one-thousand qubits (e.g., [ TIL22 ], [ FEY82 ], [ LEU00 ], [ NEG06 ], [ PLA07 ], [ MON11 ], [ MON16 ], [ CAS23 ]). Figure 5.1 (courtesy of IBM) depicts recent illustrative achievements in practical QC development at IBM, a key player in this arena (in the fall of 2023, IBM® announced the Condor prototype, the world’s first universal QC with 1,121 qubits 1 ). The generation of QCs at the time of this writing is known as Noisy-Intermediate Scale Quantum (NISQ) devices (some proponents cite this as being the third generation). These NISQ QCs are typically cooled to cryogenic temperatures (around −273° C) in order to operate efficiently; these environmental conditions are challenging to maintain in other than laboratory settings. In practical terms, QCs remain of somewhat limited and specialized functionality and are prone to computational errors. Considering these limitations, Hybrid QC (HQC) 170 171 172 arrangements and Hybrid Quantum Applications (HQApps) endeavor to combine classical and QC systems in order to undertake calculations directed at various (but specific) optimization or related use cases; tasks such as preparing inputs for quantum algorithms, storing data, or interacting with the user are typically still performed using classical computers. The number of operations in a QC typically equates with the number of quantum gates and the number of qubits supported; however, the larger the number of gates, the more likely it is that errors, including decoherence, are introduced into the quantum state. NISQ entails a somewhat limited number of logical qubits and associated physical qubits to support error correction schemes. Fortunately, a category of algorithms running on NISQ devices can proceed with only a small number of qubits and exhibit some degree of noise resilience; typically, they are hybrid algorithms, with a portion of the computational steps performed on a quantum device and with other computational steps running on a conventional computer. The bottom line is that with NISQ devices, the number of operations is typically moderate at this juncture, thus the scope and type of algorithms that can be implemented is relatively limited. However, there is research that shows that even these QCs can outperform conventional computers on a set of mathematical problems (e.g., [ PRE18 ], [ BRO19 ], [ MAD22 ]). The next step in the evolution is the interconnection of QCs over a distance network, as discussed in Chapter 6 . A classification of fundamental QC technologies has been proposed the European standards body CEN-CENELEC, specifically the Focus Group on Quantum Technologies (FGQT), which was established in June 2020 to coordinate and support the development of standards relevant for European industry and research [ OVA22 ]. See Table 5.1 .