Alexei Abrikosov, Vitaly Ginzburg and Anthony Leggett,  who were awarded the prize on Tuesday, are noted for their work on superconductivity, which helped in the development of magnetic imaging scanners.

The Royal Swedish Academy of Sciences said it was recognising the trio's theories concerning two phenomena in quantum physics - superconductivity and superfluidity.

Ginzburg, 87, was head of the theory group at the PN Lebedev Physical Institute in Moscow, and Abrikosov, 75, now works at the Argonne National Laboratory in Illinois.

Revolutionary

Briton Leggett, 65, is at the University of Illinois, Urbana-Champaign.

Abrikosov said he had begun his work more than half a century ago in the Soviet Union in a scientific world that was almost unrecognisable and virtually without computers.

"All three of us have something in common - our discoveries... were done many years ago. We are pretty old people," he said from Lemont, Illinois, on learning of the award.

Scientists say that superconductivity has still to this day potentially revolutionary applications.

Levitating trains

"Superconductivity holds the promise of a new class of electronics device which can save big energy and lead to levitating trains and improved medical imaging"

Phil Schewe,
American Institute of Physics

"Superconductivity holds the promise of a new class of electronics device which can save big energy and lead to levitating trains and improved medical imaging," Phil Schewe, chief science writer at the American Institute of Physics, said.

The theories developed by the Russian laureates laid the groundwork for discoveries on magnetic resonance imaging (MRI), the diagnostic method used by doctors to look inside the bodies of millions of patients every year.

"They developed a theory which laid the groundwork for MRI techniques," said academy member Professor Erik Karlsson.

"The Nobel prize (awarded) on Monday was partly thanks to the development of this theoretical work. They made it possible to have excellent pictures of the human body."

Albert Einstein

Leggett formulated "a decisive theory" explaining how atoms interact and are ordered in the superfluid state, the Academy said.

The Nobel prize includes a cheque for more than 10 million Swedish crowns ($1.3 million) to be shared among the three. The winners join alumni including Albert Einstein.

The Nobel prizes, first awarded in 1901, were created in the will of Swedish industrialist Alfred Nobel, inventor of dynamite, who died in 1896.