This could make it possible to build a new kind of computer far more powerful than any seen before.
Serge Haroche of France and American David Wineland, both 68, found ways to manipulate the very smallest particles of matter and light to observe strange behaviour that previously could only be imagined in equations and thought experiments.
"The Nobel laureates have opened the door to a new era of experimentation with quantum physics by demonstrating the direct observation of individual quantum particles without destroying them," said the Royal Swedish Academy of Sciences, which awarded them the $1.2-million Nobel Prize in Physics.
"Perhaps the quantum computer will change our everyday lives in this century in the same radical way as the classical computer did in the last century."
Haroche said he was walking in the street with his wife when he recognised the Swedish country code on the incoming call to inform him of the award. "I saw the area code 46, then I sat down," he told reporters in Sweden by telephone.
"First I called my children, then I called my closest colleagues, without whom I would never have won this prize," he said.
Asked how he would celebrate, he said: "I will have champagne, of course." He told Reuters he hoped the prize would give him a platform "that will allow me to communicate ideas, not just in this field of research but for research in general, fundamental research".
Physics is the second of this year's crop of awards; scientists from Britain and Japan shared the first prize on Monday, in medicine, for adult stem cell research. The prizes, which reward achievements in science, literature and peace, were first awarded in 1901 in accordance with the will of Swedish dynamite millionaire Alfred Nobel.
Quantum physics studies the behaviour of the fundamental building blocks of the universe at a scale smaller than atoms, when tiny particles act in strange ways that can only be described with advanced mathematics.
Researchers have long dreamt of building "quantum computers" that would operate using that mathematics – able to conduct far more complicated calculations and hold vastly more data than classical computers. But they could only be built if the behaviour of individual particles could be observed.
"Single particles are not easily isolated from their surrounding environment, and they lose their mysterious quantum properties as soon as they interact with the outside world," the Nobel committee explained. "Through their ingenious laboratory methods Haroche and Wineland, together with their research groups, have managed to measure and control very fragile quantum states, which were previously thought inaccessible for direct observation. The new methods allow them to examine, control and count the particles."
Both scientists work in the field of quantum optics, studying the fundamental interactions between light and matter.
The Nobel committee said they used opposite approaches to the same problem: Wineland uses light particles – or photons – to measure and control particles of matter – electrons – while Haroche uses electrons to control and measure photons.
"This year's Nobel Prize recognises some of the most incredible experimental tests of the weirder aspects of quantum mechanics," said Jim Al-Khalili, professor of physics at the University of Surrey in Britain. "Until the last decade or two, some of these results were nothing more than ideas in science fiction or, at best, the wilder imaginations of quantum physicists. Wineland and Haroche and their teams have shown just how strange the quantum world really is and opened up the potential for new technologies undreamt of not so long ago." – Reuters