Future quantum computers are expected not only to solve particularly tricky computing tasks, but also to be connected to a network for the secure exchange of data. In principle, quantum gates could be used for these purposes. But until now, it has not been possible to realize them with sufficient efficiency. By a sophisticated combination of several techniques, researchers at the Max Planck Institute of Quantum Optics (MPQ) have now taken a major step towards overcoming this hurdle.
For decades, computers have been getting faster and more powerful with each new generation. This development makes it possible to constantly open up new applications, for example in systems with artificial intelligence. But further progress is becoming increasingly difficult to achieve with established computer technology. For this reason, researchers are now setting their sights on alternative, completely new concepts that could be used in the future for some particularly difficult computing tasks. These concepts include quantum computers.
Their function is not based on the combination of digital zeros and ones—the classical bits—as is the case with conventional, microelectronic computers. Instead, a quantum computer uses quantum bits, or qubits for short, as the basic units for encoding and processing information. They are the counterparts of bits in the quantum world—but differ from them in one crucial feature: qubits can not only assume two fixed values or states such as zero or one, but also any values in between. In principle, this offers the possibility to carry out many computing processes simultaneously instead of processing one logical operation after the other.