Work could lead to revolutions in computing

By Alexandra Witze

Web edition: October 9, 2012
Print edition: November 3, 2012; Vol.182 #9 (p. 13)

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2012 Nobel Laureates

For groundbreaking experimental methods that enable measuring and manipulation of individual quantum systems

Credit: From the left: © CNRS Photothèque/Christophe Lebedinsky; © NIST

Two scientists have won the 2012 Nobel Prize in physics for their pioneering work in quantum optics, a field that manipulates light and matter to measure very precise properties of single particles.

The Nobel committee awarded the prize October 9 to Serge Haroche, of the Ecole Normale Superieure in Paris, and David Wineland, of the National Institute of Standards and Technology in Boulder, Colo.  The two were cited for related but independent work: Haroche bounces light particles between mirrors to probe their quantum states, and Wineland creates traps for charged atoms and shoots in laser light to control those particles.

Discoveries based on those experiments have already been used to develop ultra-accurate atomic clocks and could eventually lead to the development of quantum computers much faster and more secure than existing electron-based technology.

“The two of them together are the total pinnacle of the whole field,” says Jonathan Home, a physicist at ETH Zurich and former member of Wineland’s group. “It’s a great achievement.”

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Trapping beryllium ions in an ultraviolet laser beam (colorized image shown) allows researchers to precisely measure the ions’ quantum states, work for which David Wineland shares this year’s Nobel Prize.

Credit: NIST

Studying individual particles in the quantum realm is tough because the very act of measurement usually destroys the information being sought. To get around that problem, researchers have developed ways to trap and handle particles delicately while probing them for information about their quantum states.

In 1978, Wineland and his colleagues did some of the first experiments using trapped electrically charged particles, or ions. His team developed ways to cool the ions and extract quantum information from them. Such information, such as the orientation of the ions’ magnetism, may one day be used as a bit of information in quantum computers much as 1s and 0s make up the stream of bits in a classical computer.

Trapped ions can also be used to improve atomic clocks, which rely on ultra-precise, natural fluctuations such as certain regular transitions within an ion. Wineland’s team has made atomic clocks so accurate that scientists can measure relativistic effects over extremely short distances or time periods. The most accurate clock in the world, which uses aluminum ions, sits in his lab in Boulder.

Haroche, for his part, uses mirrors to bounce light particles around and store them for a very long time, relatively speaking. Photons can bounce between the two mirrors for more than a tenth of a second before disappearing; during that time they might travel 40,000 kilometers before vanishing.

Like Wineland, Haroche has used his experimental setup to create quantum states inspired by the famous Schroedinger’s cat paradox. In this, a quantum system exists in a superposition of two states (such as the cat being both alive and dead at the same time) until a measurement is made and the system is resolved into one of the two possible states. In 2008, Haroche’s team described creating versions of these states and making a movie as they evolved from the quantum into the everyday world (SN Online: 9/24/08). 

The work of both laureates is an early step toward quantum computers, which are a long way from reality but could one day be a far faster and more secure method for certain types of computing. “These are two great experimentalists and I’m really glad they won,” says Robert Garisto, a physicist and editor at the journal Physical Review Letters.

Haroche said he had been walking with his wife when he saw the Swedish calling prefix pop up on his phone this morning. “I was in the streets passing near a bench, so I was able to sit down,” he said. “We have champagne at home.”

Wineland, in Colorado, was awoken by the phone call from the Nobel committee. “We probably won’t go back to sleep for a while,” he said a few minutes later in an audio interview posted at the Nobel web site.

This year’s physics prize is worth 8 million Swedish kronor, or about $1.2 million, and will be shared equally between the winners.