Quantum computers explained: potential, limits and the current state of the art

The quantum computer represents a technological revolution with enormous potential. From medicine and logistics to AI and cryptography – many areas could be fundamentally transformed by its computing power. However, we currently still face many technical hurdles. With the growing number of research institutions and increasing collaboration between academia and industry, one thing is clear: the future of quantum computing has already begun and will be showcased at Quantum Photonics.

What is a quantum computer?

A quantum computer is a completely new type of computing system based on the principles of quantum mechanics. Unlike classical computers, which operate with bits that can assume either the value 0 or 1, a quantum computer uses so-called qubits. These quantum bits can occupy multiple states simultaneously thanks to phenomena such as superposition and entanglement. This opens up enormous new computing possibilities.

Superposition allows a qubit to be in the states 0 and 1 simultaneously. In combination with quantum entanglement – ​​in which two or more qubits are connected in such a way that a change in one directly affects the other – this creates powerful computing models that can significantly outperform classical systems in certain tasks.

The Potential of Quantum Computers

1. Revolution in Computing Power

The greatest advantage of quantum computers lies in their ability to perform extremely complex calculations in significantly less time. While a conventional computer must consider each possibility individually when solving difficult tasks, quantum computers can analyze large amounts of data simultaneously through parallel processing.

2. Breakthrough in Medicine and Materials Research

In molecular research, quantum computers can help develop new drugs by precisely simulating the interactions between molecules. In materials research, they also enable the development of new materials with precisely defined properties – something that would take years with conventional computers.

3. Optimization of Complex Processes

Quantum computers offer enormous potential for logistics and industry. Route planning, traffic flows, and production chains can be optimally controlled with their help. The simultaneous analysis of countless combinations can provide solutions that were previously considered impractical.

4. A New Era of Artificial Intelligence

The combination of quantum computing with machine learning opens up entirely new possibilities in AI development. Learning algorithms could be trained more quickly and patterns could be recognized more efficiently – a major step towards more powerful artificial intelligence.

5. Advances in Cryptography

The impact of quantum computers on cryptography is a double-edged sword. On the one hand, they could crack existing encryption methods such as RSA in a very short time. On the other hand, they promote the development of so-called quantum-safe encryption, which is based on quantum mechanics and is intended to withstand future attacks.

The Limits of Today's Quantum Computers

Despite their great potential, we are still at the beginning of the quantum revolution. The technology is no longer in its infancy, but many challenges still need to be overcome before quantum computers can become part of everyday life.

1. Error susceptibility and stability

A key problem is the high error susceptibility of current systems. Qubits are extremely sensitive to external influences such as temperature, radiation, or magnetic fields. Even the smallest disturbances can corrupt calculations. The so-called quantum coherence—the period of time during which a qubit remains in a superimposed state—is extremely short and difficult to control.

2. High technical complexity

The infrastructure of a quantum computer is very complex. Current systems require special cooling systems to reach temperatures close to absolute zero (-273.15°C). The sensitive qubits only function stably under these conditions. This makes their production and operation extremely expensive.

3. Lack of Standardization

While hardware and software standards have long been established for classical computers, universal interfaces are still lacking in the quantum world. Different research groups and companies are pursuing different architectures and programming languages, which makes compatibility difficult.

4. Limited Practical Applications

Although some problems have already been solved with quantum computers, these mostly involve specific, highly theoretical issues. Powerful and error-corrected systems are still lacking for everyday problems or widespread use in business.

The current state of the art

Major tech companies like Google, IBM, Microsoft, and startups like Rigetti and IonQ are investing billions in quantum research. Research centers dedicated to developing this technology are also increasingly being established in Europe.

IBM operates one of the first publicly accessible quantum ecosystems, the "IBM Quantum Network." In 2019, Google caused a stir with the term "quantum supremacy" when a quantum chip solved a problem in seconds that would have taken a supercomputer thousands of years – although this result was later downgraded.

Technological approaches

There are different physical approaches to realizing quantum computers:

• Superconducting qubits: Here, current flows losslessly in microscopic circuits, which occurs at extremely low temperatures.
• Ion traps: Individual ions are manipulated with lasers and held in an electromagnetic trap.
• Photonic quantum computers: Light particles perform the computational work, which could make room-temperature operation possible. This approach is considered particularly promising for scalable and energy-efficient systems.
• Topological qubits: A promising, but still immature, technology with theoretically very high error resistance.

Quantum Computers in the Cloud

Another milestone in the development is cloud access to quantum computers. Platforms such as IBM Q, Amazon Braket, or Microsoft Azure Quantum allow users worldwide to test simple quantum algorithms – without the need for their own hardware. This significantly lowers the barriers to entry and makes the technology accessible to smaller companies and research groups. Cloud-based access promotes innovation, accelerates the development of new applications, and facilitates knowledge transfer between industry and academia. At the same time, it enables practical experiments with real quantum hardware, significantly advancing the further development and understanding of quantum computing.

The future: When will quantum computers arrive in everyday life?

Despite all the progress, the use of quantum computers in everyday life is still a distant prospect. Experts believe it will take at least another decade before quantum computers are widely available. However, quantum algorithms are already generating new ideas for solving problems more efficiently – and this is precisely where true progress lies.

In the long term, quantum computers may not replace traditional computers, but rather complement them meaningfully – as highly specialized systems for particularly complex tasks.

Conclusion

The quantum computer represents a technological revolution with enormous potential. From medicine and logistics to AI and cryptography – many areas could be fundamentally transformed by its computing power. However, we currently still face many technical hurdles. With the growing number of research institutions and the increasing collaboration between science and industry, one thing is clear: the future of quantum computing has already begun.