What is Quantum Computing, How Does It Work, and Why It’s the Future?

Quantum computing represents one of the most fascinating and promising frontiers of modern technology. Unlike traditional computers, which process information using binary bits (0 or 1), quantum computers exploit qubits, capable of existing simultaneously in multiple states thanks to the principles of quantum mechanics, such as superposition and entanglement. This characteristic allows them to tackle complex problems with a speed and efficiency unattainable for classical systems.

In recent years, the field of quantum computing has seen significant progress, attracting the attention of companies, academic institutions and governments around the world. Potential applications range from advanced cryptography to the simulation of chemical processes, from the optimization of complex systems to artificial intelligence. Despite the technical challenges that still need to be overcome, such as error management and system scalability, the enthusiasm and investment in the sector suggest that quantum computing could revolutionize many areas of our daily lives in the near future. In fact, it is already doing so.

What is quantum computing and what are quantum computers

Quantum computing, as mentioned, exploits the laws of quantum mechanics, that part of physics that studies the smallest particles and how they assume more than one state at the same time. It is a technology that is continually evolving and will be able to provide increasingly faster computing solutions. For this reason, established companies and governments are involved in its development and it is a breeding ground for startups.

But let’s put things in order and give a precise and technical definition of quantum computing:

quantum computing is a discipline that combines computer science and quantum mechanics to develop new computing paradigms. The heart of this technology is the qubit, or quantum bit, which unlike the classical bit can be in a superposition of states, simultaneously representing both 0 and 1. This property derives from the principle of quantum superposition, which allows qubits to explore multiple solutions at the same time.

Explaining it in the simplest way possible, this means that qubits, in traditional computing logic, can be both a zero, as well as a one, or even both at the same time, that is, they can form the so-called superposition. Another fundamental characteristic is entanglement, a phenomenon by which two or more qubits become interdependent, allowing instantaneous correlations regardless of the distance that separates them.

These features allow quantum computers to perform complex calculations in significantly less time than traditional computers. However, the practical realization of such systems presents significant challenges, including the coherence of qubits, error correction and the need to operate at temperatures close to absolute zero to maintain the stability of quantum states. Both academic and industrial research have been working for years now to create devices based on quantum computing that can be widespread use, in the long term and, above all, that are error-free.

When was quantum computing born? A bit of history

The origins of quantum computing can be traced back to 1935, when Albert Einstein tackled quantum matter together with other scientists, such as Boris Podolsky and Nathan Rosen. But we have to go back to 1981 to find the first application of quantum theory to computers, by the physicist Paul Benioff, who proposed a model of a Turing machine and the idea that a quantum computer could perform operations superior to those of a classical computer is attributed to the work of Richard Feynman and Jurij Manin.

In 1992 we see the first algorithm that exhibits a quantum advantage and the real turning point comes two years later, with Peter Shor’s algorithm for factoring integers in polynomial time that raises doubts about the invulnerability of RSA asymmetric cryptography. Let’s come to the beginning of the century, with Ibm demonstrating the first quantum algorithm calculation and with the first commercial quantum computer produced by D-Wave in 2012. In 2019, IBM again proposed its first quantum computer, the IBM Q System One, usable in the cloud, and Google also effectively entered the arena of quantum supremacy, claiming to have completed in three and a half minutes a calculation that would have taken thousands of years using a quantum computer.

Why quantum computing is more powerful than traditional computing

Later we will see how qubits work. In the meantime, let’s try to understand why quantum computers are more powerful than traditional ones, even if these take the form of supercomputers, that is, those large systems used by engineers and scientists and characterized by the work of thousands of CPUs (Control Process Units) and GPUs (Graphical Process Units), that is, processors and graphic coprocessors. But supercomputers are not always able to solve all problems. This is what Ibm itself, which created large computers starting from mainframes, says. If a supercomputer crashes, explains IBM, it is probably because it has been asked to solve a problem with too high a degree of complexity. So what is a complex problem? It is a problem with many variables, which relate to each other in complicated ways.

The examples are well-known and often cited: they range from modeling the behavior of atoms in a molecule, but also to finding the ideal arrangement to seat a group of ten people at the table, each of whom has preferences regarding the people to have next to them. Important problems of collective value or trivial problems, it doesn’t matter: what makes the difference are the combinations of mathematical calculation, which can put a traditional computer in crisis, forcing it to perform long calculations. The fact is that quantum computers are faster and in fact we speak of quantum supremacy. This terminology refers to the empirical measurement of the greater effectiveness of quantum computers compared to traditional computers in solving certain categories of problems.

And quantum supremacy itself is not a defined concept, it does not lie on a fixed line: its boundary is constantly changing, the bar is raised, because the technology industry develops algorithms capable of increasing the supercomputing performance of classical computing.

How do quantum computers work?

IBM also offers us an example that explains in a simple way how quantum computers can succeed where classical computers fail: understanding how proteins behave, a topic that has important implications for medicine and the human sciences. A classical supercomputer may be suitable for carrying out operations such as sorting a large database of protein sequences, but it struggles to find in that data the patterns that determine the behavior of proteins, which are long strings of amino acids that fold into complex shapes.

The supercomputer can use its processors to test every possible way to fold the chemical chain, but when the protein sequences become longer and more complex, the supercomputer grinds to a halt. Theoretically, a chain of 100 amino acids could fold in trillions of ways, and no computer has the capacity and memory to consider all the possible combinations of individual folds. Quantum algorithms, on the other hand, approach these complex problems by creating multidimensional spaces in which patterns emerge that connect individual data points. Classical computers cannot create these spaces and therefore cannot find the patterns. Quantum computers are machines that require less energy than supercomputers: a quantum processor is not much larger than a laptop, and the machine that houses it mostly requires cooling systems to keep the processor at the low temperature (close to freezing) necessary for its operation, unlike traditional computers, which are typically cooled by fans. Supercooled fluids are used to allow electrons to move without encountering resistance.

They are therefore called superconductors: when electrons pass through superconductors they pair up, forming "Cooper pairs", which carry a charge through barriers, or insulators, in a process known as quantum tunneling. We said that if a classical processor uses bits to perform operations, a quantum computer uses qubits to run multidimensional quantum algorithms. Remember that qubits operate differently from normal computer bits in that each qubit can be both a 1 and a 0 at the same time. This type of superposition allows quantum computers to process information in faster ways to solve complex problems. The qubit puts quantum information into a state called superposition, which represents a combination of all possible configurations. Groups of superimposed qubits can create complex, multidimensional computational spaces. It is in these spaces that complex problems are represented in new ways.

Where quantum computing is already being used

The applications of quantum computing are rapidly expanding, finding application in several key sectors.

Due to its unusual processing power, quantum computing is targeting sectors that are traditionally computationally intensive, such as finance, healthcare and the humanities, and artificial intelligence, understood as a macro technological sector that finds outlets in any discipline.

• In chemistry and pharmacology, quantum computers can accurately simulate molecular interactions, accelerating the discovery of new drugs and materials.
• In the finance sector, these technologies offer advanced tools for portfolio optimization, risk management and the development of more efficient trading strategies.
• Furthermore, quantum computing has the potential to revolutionize artificial intelligence, improving machine learning and large-scale data processing.
• Logistics and supply chain management can also benefit from quantum algorithms to optimize routes and processes, reducing costs and times.
• Finally, quantum cryptography promises to raise the security standards in communications, making data practically inviolable thanks to protocols based on quantum principles.

Use in finance
These applications highlight how quantum computing can profoundly transform various sectors, offering innovative solutions to complex problems. According to the American analysis company, Inside Quantum Technology Research, already at the end of 2019, Bank of America said that quantum computing would be revolutionary in the following decade, on a par with smartphones in the 2010s. Fundamental technology for financial services according to Goldman Sachs, JPMorgan, Citigroup and Wells Fargo, quantum computing is also attracting European and Asian banks, insurance companies, credit card companies, financial advisors and hedge funds. The idea is to employ quantum computing in portfolio management and construction, fraud detection, CRM, credit scores, risk modeling, pricing of derivatives.
According to Inside Quantum Technology, quantum computers, less expensive in terms of operation, could also be used profitably in smaller financial institutions and in transactional networks.

The use between AI and machine learning
Regarding the human sciences sector, called protein research, there are numerous examples of its use in the chemical and biological fields, from pharmaceutical research to the creation of new materials, from the evolution of viruses to the creation of vaccines. The predictive aspect is precisely one of the factors that drive the use of quantum computing and that combine it with the large field of action of artificial intelligence.
Production line optimization, fault detection, transport planning, are three examples in as many production and service fields that trace a line of connection between quantum computing and machine learning. The same machine learning models can have generalization problems and since they are assigned the task of making increasingly precise predictions, they become more complex, require data and their calculations become more expensive. In this case, quantum computing is a turning point, because it promises improved performance and better generalization. The discipline is still in its infancy, but QML (Quantum Machine Learning) can already be used in hybrid approaches to accelerate computation and increase precision.

Which companies offer quantum computing

Many technology companies are involved in development projects in the quantum computing field. We can mention Toshiba, Nec, Fujitsu, At&T, Mitsubishi, BT, Alibaba, Nokia in the communications field.

Already today, therefore, several leading companies in the technology sector are investing significantly in quantum computing, offering services and platforms to exploit this emerging technology.

• IBM is among the pioneers, making available IBM Quantum Experience, a platform cloud that allows researchers and developers to access its quantum computers for experimentation and algorithm development.
• Google recently announced significant progress with its quantum chip "Willow", which can perform complex calculations in extremely short times, opening up new possibilities for practical applications in various industries.
• Microsoft offers Azure Quantum, a platform that integrates quantum solutions in the cloud, allowing users to develop and test quantum algorithms using different qubit technologies.
• NVIDIA, although primarily known for its GPUs, has developed NVIDIA Quantum Cloud, providing tools for quantum simulation and algorithm development, supporting the quantum ecosystem with advanced hardware and software solutions.
• Amazon Web Services provides Amazon Bracket, a fully managed quantum computing service designed to help accelerate scientific research and software development to solve complex problems.
• Finally, companies like IonQ are developing quantum hardware based on innovative technologies, offering access to their systems through cloud platforms, contributing to the expansion of the accessibility and adoption of quantum computing.

These initiatives highlight the private sector’s commitment to making quantum computing a tangible reality, accelerating innovation and the integration of this technology into real-world applications.

Original article published on Money.it Italy. Original title: Cos’è il quantum computing, come funziona e perché è il futuro