Physicist's Theory Leads to Experiment by Nobel Prize Winner

FAYETTEVILLE, Ark. – In the early 1990s, a University of Arkansas physicist showed a new way to realize one of the fundamental problems in quantum physics, observing a particle in multiple states, leading one of the current Nobel Prize winners in physics to successfully do so in his experiments.

Julio Gea-Banacloche, a physicist in the J. William Fulbright College of Arts and Sciences, calculated that a single atom placed into an existing electromagnetic field would “split” the field, allowing it to exist in two states at once.

This central paradox of quantum physics can be illustrated by “Schrödinger’s cat,” a thought experiment described by Nobel Laureate Erwin Schrödinger in 1935. Imagine you have a cat in a cardboard box. Without direct observation, the cat could be thought of as existing in two states at the same time — both alive and dead — until the minute someone observes it, when it must be either alive or dead. In the same way, quantum particles can have multiple states at once, but when a scientist tries to observe these multiple states, they collapse into one.

“Back in the early 90s, several groups were coming up with ideas to make ‘Schrödinger cats’,” Gea-Banacloche said, “and I realized there was one ‘hiding,’ as it were, in the particular system I was studying.”

In 2003, 12 years after Gea-Banacloche’s initial paper, a team led by one of this year’s Nobel Prize winners in physics, Serge Haroche, currently at the Collège de France in Paris, published experimental findings showing the theoretical predictions to be true.

“Haroche and his team had made ‘cat’ states before by other methods, but they found my proposal intriguing enough to pursue,” Gea-Banacloche said. “Their experiment was beautiful. They essentially were able to see “Schrödinger’s cat” in the two states inside the box.”

Haroche and David J. Wineland of the National Institute of Standards and Technology in Boulder, Colo., won this year’s Nobel Prize in physics for their work in measuring and manipulating individual quantum systems such as the one Gea-Banacloche theorized.

Gea-Banacloche has continued work in quantum theory, but has moved from “cats” to computing. He has spent the past 15 years looking at the theory behind quantum computing – a revolutionary way of using simultaneous multiple quantum states to generate and store vast amounts of information using only a tiny number of quantum particles.