STOCKHOLM, Sweden — Two American citizens and a Russian won the 2003 Nobel Prize in physics Tuesday for theories about how matter can show bizarre behavior at extremely low temperatures.

The Royal Swedish Academy of Sciences cited Alexei A. Abrikosov, 75, Anthony J. Leggett, 65, and Vitaly L. Ginzburg, 87, for their work concerning two phenomena called superconductivity and superfluidity.

Abrikosov is a Russian and American citizen based at the Argonne National Laboratory in Illinois; Ginzburg is a Russian based at the P.N. Lebedev Physical Institute in Moscow; and Leggett is a British and American citizen based at the University of Illinois at Urbana-Champaign.

The $1.3 million prize money will be shared equally among the three winners.

Leggett said he was surprised. "I guess it had occurred to me that it was a possibility I might get the Nobel Prize, but I didn't think it was particularly probable."

Abrikosov, on the other hand, said the news didn't shock him. He said he had been nominated several times before. "And since this had never happened before, I saw this as a good sign," he said.

"I feel now relief," he said. "I had lost hope of winning. . . . But I thought my life is good even without (the Nobel Prize). I have interesting work. I am happy. I love my family."

Reached by phone at the Lebedev institute, Ginzburg said he had long given up hope of ever receiving a Nobel.

"They have been nominating me for about 30 years, so in that sense it didn't come out of the blue. But I thought, 'Well, they're not giving it to me, I guess that's it.' After all, there are a lot of contenders. So, you know, I had long ago forgotten to think about this."

Asked how he was planning to celebrate, he said: "I haven't thought about it yet. Now I'm supposed to write a paper, and if I'm healthy, I'll go to Sweden."

The two phenomena the researchers studied are linked, in that superconductivity arises from how pairs of electrons behave, while superfluidity comes about from pairings of atoms.

Superconductivity is the ability of some materials to conduct electricity without resistance when they are chilled to low temperatures.

Superconducting magnets are used to produce powerful magnetic fields for the standard body scanning technique called magnetic resonance imaging, or MRI. Other discoveries concerning MRI were honored Monday with the Nobel medicine prize.

Researchers hope to harness superconductivity for such uses as power lines that can conduct current without waste to resistance and high-speed trains that float above the tracks.

Abrikosov and Ginzburg were honored for theories about superconductivity.