The long sought-after quantum computers - a superfast technology touted as the next big revolution in computers - may not be in the market in at least 10 years, according to scientists, including German Nobel Laureate Klaus Von Klitzing.
Quantum computers leverage the characteristics of quantum mechanics to solve problems faster than regular computers.
They have long been thought to spur the development of new breakthroughs in science, life-saving medications and, machine learning and diagnosing diseases faster.
Klitzing, 76, who was awarded the 1985 Nobel Prize in Physics for the discovery of the integer quantum Hall effect, said that quantum computers, when available, will not replace the traditional systems in use and would mostly be applied in research and industries.
"I don't see quantum computers launching in another 10 years, and even if they come I feel they won't be available for day-to-day calculations for common people,” Klitzing told PTI during the 69th Lindau Nobel Laureates Meeting here.
Elena Jordan from the National Institute of Standards and Technology (NIST) in the US agreed with Klitzing.
"Quantum computers that can outperform classical computers will not be available in the near future. This is because they are still in the development phase," said Jordan, a postdoctoral researcher affiliated to the University of Colorado Boulder.
"There are small quantum computers that can be seen as a proof of principle, but the majority of research groups are still trying to improve single gate operations like better fidelity and increased speed. They are far from offering a fully programmable quantum computer with a large number of qubits," she told PTI.
Jordan is hopeful that there will be useful quantum simulators that can only be used for a limited kind of tasks - that is to simulate a different quantum system which is hard to study otherwise.
"These simulators will be of interest for basic research," said Jordan.
While a classical computer has a memory made up of bits, where each bit is represented by either a one or a zero, a quantum computer, on the other hand, maintains a sequence of qubits, which can represent a one, a zero, or any quantum superposition of those two qubit states.
"Complex phenomena in nature, which are otherwise difficult to realise in a laboratory or intractable on a classical computer, can be simulated in a quantum computer. A quantum computer will be the next home for innovative ideas and theories. Based on the new theories, new materials, drugs or devices can be manufactured. This may eventually help us in technical advancement and improving human health," noted Manoj K Joshi from the Institute for Quantum Optics and Quantum Information in Austria.
"Simple and small quantum computers already exist in laboratories but if you ask about a fully-fledged machine running on its own with its full power perhaps we will have to wait for that a bit," said Joshi, noting that some initiatives from the corporate sides, such as IBM Q, DWave and Google AI are already in place.
Klitzing, the director of the Max Planck Institute for Solid State Research in Germany said that quantum computers may be helpful in limited fields while normal computers are a backbone of the society.
"I don't think if we will ever need a quantum computer inside a smartphone or for the purpose of solving general arithmetic problems. It will have applications in research as well on the technical/corporate side," Joshi, who is also associated with the University of Innsbruck in Austria told PTI.
The scientists think that it is expected that quantum computers can be used to solve hard optimisation problems, guarantee secure communication, and help to find new molecules for medication or fertilizers that can make life better for many people.
"I think classical computers will remain most important for general use. In the future, it might be that a smaller quantum computer part is used for secure communication, true random number generators in the computers that can, for example, be used for encryption," said Jordan.
"An important point is, that quantum computers are only expected to outperform classical computers on certain tasks, not in general," she said.
Jordan feels, in research and industry, quantum processors can become useful for certain optimisation problems that are hard problems for classical computers and cannot be solved efficiently.
For example, she said, Microsoft is developing quantum computer algorithms that calculate the structure of new molecules that are optimised for medication or fertilizers.
However, Jordan noted that fully programmable quantum computers with a large number of qubits are expected to outperform classical computers on certain tasks, but not in general.
"From the laboratory side, many countries in Europe, China and the USA are putting their efforts to build small quantum machines. At the moment they are limited to tens of qubits only and are being used only for testing toy models in science," Joshi added.