Quantum computers are considered the most groundbreaking revolution in information technology since the invention of the classical computer.
The quantum computer technology promises to perform calculations that would be virtually impossible with conventional computers. But what exactly are quantum computers, how do these innovative systems work, and why is so much potential attributed to them? In this article, we explain the key aspects of quantum computing in a way that is both understandable and well-founded.
What is a quantum computer?
A quantum computer uses the principles of quantum mechanics to process information. While classical computers store data in bits (0 or 1), quantum computers use qubits (quantum bits), which can be 0, 1, or both simultaneously thanks to the phenomenon of superposition.
This feature allows quantum computers to perform certain calculations exponentially more efficiently than conventional systems. They can solve complex problems that even the most powerful supercomputers would fail at.
The basic principles of quantum computing
Quantum computers are based on three central concepts of quantum physics:
- Superposition: Qubits can exist in multiple states at once. While a classical bit must be either 0 or 1, a qubit can occupy a superposition of both states, enabling the simultaneous processing of exponentially larger amounts of data.
- Quantum entanglement: Qubits can be entangled with each other, meaning the state of one qubit is directly linked to the state of another, regardless of spatial distance. This “spooky action at a distance,” as Einstein called it, enables novel computation methods.
- Quantum interference: Through targeted manipulation, the probability of certain computational outcomes can be amplified or canceled out, allowing quantum algorithms to find solutions that remain hidden to classical algorithms.
How quantum computers work
A modern quantum computer consists of a precise arrangement of qubits that are manipulated by quantum gates. These gates specifically alter the states of the qubits and implement the logic of quantum algorithms. Unlike classical computers, calculations do not occur sequentially but in parallel across a multitude of quantum states.
The physical control depends on the technological approach and may involve microwave pulses, lasers, magnetic fields, or electrical signals. At the end of a quantum calculation, the complex quantum state is measured, causing the superposition to collapse and yielding a concrete measurement result.
The art of quantum computing lies in designing algorithms in such a way that the probability of obtaining the correct result upon measurement is maximized.
Leading technological approaches
Currently, various physical implementations are competing in the development landscape:
- Superconducting circuits: Companies like IBM and Google rely on superconducting qubits operated at extremely low temperatures. This technology has already enabled the first demonstrations of quantum supremacy.
- Trapped ion quantum computers: Companies like IonQ and Honeywell use single charged atoms held in place by electromagnetic fields and manipulated with lasers, offering especially long-lived and precise qubits.
- Photon-based quantum computers: Companies like Xanadu are developing optical quantum computers that use individual light particles as information carriers and can partly operate at room temperature.
- Silicon quantum dots: This technology uses single electrons in semiconductor materials and promises high compatibility with existing manufacturing processes.
- Adiabatic quantum computers: D-Wave Systems specializes in this approach, which is particularly suited for optimization problems.
Promising fields of application
Quantum computers will not replace classical computers but will complement them for specific computational problems:
- Quantum cryptography and cybersecurity: Quantum computers could break many current encryption methods but also enable new communication techniques that are theoretically completely secure.
- Materials science and chemistry: The precise simulation of complex molecules could revolutionize the development of new drugs, materials, and energy-efficient batteries.
- Optimization problems: Quantum algorithms could find optimal solutions for complex problems in logistics, supply chain optimization, and resource allocation.
- Machine learning and AI: Quantum computers promise exponentially faster training methods for AI models.
- Climate modeling: The computation of complex climate models could become more accurate and detailed.
Challenges in quantum computer development
Despite impressive progress, significant hurdles remain:
- Quantum decoherence: Quantum information is highly sensitive to environmental influences and can easily be lost. Maintaining the delicate states remains a central challenge.
- Quantum error correction: Effective error correction mechanisms must be implemented to perform reliable calculations.
- Scalability: Building large systems with hundreds or thousands of error-free qubits poses enormous technical demands.
- Extreme cooling: Many architectures require temperatures near absolute zero, necessitating specialized cooling systems.
- Algorithm development: Developing practically usable quantum algorithms remains an active field of research.
Current state of the technology
We are currently in the NISQ era (Noisy Intermediate-Scale Quantum) with quantum computers that have dozens to hundreds of qubits but still suffer from significant error rates.
An important milestone was Google’s demonstration of quantum supremacy in 2019, where a 53-qubit quantum processor solved a specific task in about 200 seconds that would have taken the most powerful classical supercomputer an estimated 10,000 years.
Despite rapid progress, the breakthrough to fault-tolerant and practical quantum computers will likely require years of intensive research.
A global innovation race has begun: Tech giants like IBM, Google, and Microsoft are investing billions, while specialized providers like IonQ and D-Wave are convincing with novel approaches.
Research institutions are providing foundational insights, and governments around the world are supporting strategic quantum technology initiatives to strengthen their technological sovereignty.
Questions and answers about quantum computers
What are quantum computers?
Quantum computers are machines that do not use classical bits but qubits, which follow the laws of quantum mechanics. This enables them to solve certain problems exponentially faster than conventional computers. Their extraordinary performance is based on the effects of superposition, entanglement, and interference. Quantum computers open up entirely new possibilities in areas such as materials research, cryptography, and optimization tasks.
What are qubits, simply explained?
Qubits are the smallest units of information in a quantum computer. Unlike a classical bit, which can only be 0 or 1, a qubit can be both 0 and 1 at the same time. This is made possible by superposition. Additionally, qubits can be entangled, allowing them to jointly process and store information in highly complex ways.
How much faster is a quantum computer?
It depends on the task. For certain problems like factoring large numbers or finding optimal solutions, quantum computers can be many times (millions or even billions of times) faster than classical computers. For everyday tasks, classical computers often remain more efficient. The extent of a quantum computer’s advantage strongly depends on the algorithm used and the technological maturity of the system.
Conclusion: Transformative technology of the future
Quantum computers offer enormous potential for science, industry, and society. They could solve fundamental problems that are practically unsolvable with today’s computing technology – from optimizing complex systems and developing new materials to deciphering the deepest mysteries of quantum physics itself.
Quantum computing research has become a global race. Those who engage with quantum computing today are positioning themselves in a revolutionary field of technology that will increasingly gain importance in the coming decades and may transform our entire digital infrastructure. The quantum revolution has only just begun, and its impact is expected to be as profound as the invention of the classical computer once was.