Experts: Andreas Fuhrer (IBM Research – Zurich)
Quantum computers promise to solve certain computer-science problems that conventional computers cannot. Considerable progress has been made in the construction of quantum computers in recent years. Nevertheless, it will take time before they can fully demonstrate their superiority.
Picture: IBM
Conventional computers, regardless of whether they are smartphones or data-centre mainframes, calculate using electrical current: All information that such a computer stores, processes or outputs is in the form of current or non-current, represented by bits, which can assume the values 0 or 1. In contrast, quantum bits (‘qubits’) can assume multiple states simultaneously, in superposition. While a conventional 8-bit register in a chip based on microelectronics can only assume one of 256 states (= 28), a register with 8 qubits can, to put it in a somewhat simplified way, assume any combination of all 256 states simultaneously. Consequently, a quantum computer has the ability to process much larger problems using far fewer bits, or qubits. However, results from such quantum computers are often not unique, but determined by a statistical distribution of multiple measured values. Therefore, depending on the algorithm, the calculations have to be repeated several times in order to make the correct results stand out from among the rest in a statistically significant way.
Researchers adopt different technical approaches to creating quantum computers. On one hand, there are quantum systems that simulate only one specific problem, such as the interaction between two molecules or a specific optimisation problem. Such systems are like building a model to simulate another, inaccessible, system in the laboratory. This makes it possible to learn more about the properties of the simulated system. On the other hand, there is research into universal quantum computers that can be freely programmed, rather than specialising in a single problem.
As quantum systems are analogue at qubit level and operate using extremely small amounts of energy, they are more susceptible to interference than the circuits in today’s digital electronics. They have to be shielded as hermetically as possible from environmental influences and, depending on the technology, must also be operated at temperatures close to absolute zero. The control devices with which the changes in state are caused or read out (lasers or microwave sources) also need to be very precise.
There are more and more start-ups (Alpine Quantum Technologies (AQT), Atom Computing, Coldquanta, Diraq, Equal1, IonQ, IQM, Pasqal, Quantum Motion, QuEra Computing, Rigetti Computing, SpinQ, SQC, Xanadu etc.) and large firms (Alibaba, Amazon, Baidu, Google, IBM, Intel, Quantinuum etc.) marketing, or wanting to market, various quantum processors. At the moment, these offers vary greatly – from small 2-qubit systems for research purposes, which are already available for under 10,000 Swiss francs, to quantum cloud access, based on processors with several hundred qubits.
Due to the differences between quantum computers and conventional computers, the former also have to be programmed completely differently. Consequently, not only is new hardware needed, but fundamentally new system architecture too. This comprises hardware, software, and how they interact – with each other and with conventional computers. Thus, quantum computers also require completely new programming environments and algorithms.
There are a number of applications for today’s quantum computers: some are exploratory, others are demonstrational. Most involve problems that conventional computers can only solve with a great deal of computing capacity or with approximation methods. So far though, due to the advances made in conventional algorithms, normal computers have usually proved to still be ahead in comparison. This is because the usefulness of today’s quantum systems is limited by the occurrence of errors. Thus, as part of efforts to create a commercially usable quantum computer, intensive research is currently being conducted on built-in continual error correction that will eliminate errors that occur during operation. Alternative approaches are attempting to achieve the necessary quality of results by means of post-processing.
If scientists succeed in further improving and scaling up the quantum processors used for computingp, quantum computers will be a more efficient means of solving important problems than conventional supercomputers in just a few years.
Quantum computing is thus seen as having the potential to solve computer-science problems that still cannot be solved with normal supercomputers. Hence, in recent years, there has been a lot of movement in the research field of quantum information science, with significant investment in both the public and private sectors. Although problems solved with today’s quantum computers are still of a rather demonstrationsl and exploratory nature, and primarily serve scientific purposes, they nevertheless demonstrate the strengths of such systems. Today’s quantum computers can solve problems of a scale that their conventional counterparts can generally also handle.
Alongside efforts in basic research, large IT companies and research centres are already looking into the issue of how complete quantum computing systems can be created and integrated into data centres in the future. This will require a whole network of both hardware and software suppliers, and is currently prompting a lot of investment in firms that are active in this area. Of course, this is partly due to the attention that is being paid to the topic: The high expectations are a strong driving force. However, they also carry the risk of false promises being made for marketing reasons, or of research results being presented as more groundbreaking than they actually are. The latter must be avoided in order to keep driving forward the further development of this technology.
Switzerland is very well positioned across this whole technological spectrum to continue making significant contributions in the future, regardless of which approach to building quantum computers ultimately prevails.
However, no country will single-handedly master the task of making quantum computing successful. On one hand, a corresponding ecosystem of suitable technology suppliers and technology users is needed. Here, there is still great potential for Swiss firms to better market or appropriately adapt their focus on high-precision, high-quality products in quantum-technology as elsewhere. On the other hand, research in Switzerland also depends heavily on international networking. The end of Switzerland’s association with Horizon Europe means that participation in large European projects is at risk. The position established via early funding of basic research (National Centre of Competence in Research QSIT and National Centre of Competence in Research SPIN) can only be maintained by continuing to make sufficient research and development investment in quantum computing and the associated technology ecosystem. This has been recognised to some extent and in 2022, the Swiss Quantum Commission SQC was founded under the leadership of the Swiss Academy of Sciences (SCNAT), as a new mechanism to coordinate Swiss efforts. In any case, it is still essential that Swiss firms and researchers remain involved internationally and able to participate as partners in the many large-scale projects in Europe and around the world.
