Experiments using laser light and pieces of gray material the size of fingernail clippings may offer clues to a fundamental scientific riddle: What is the relationship between the everyday world of classical physics and the hidden quantum realm that obeys entirely different rules?
"We found a particular material that is straddling these two regimes," said N. Peter Armitage, an associate professor of physics at the Johns Hopkins University who led the research for a paper just published in the journal Science. Six scientists from Johns Hopkins and Rutgers University were involved in the work on materials called topological insulators, which can conduct electricity on their atoms-thin surface, but not in their insides.
Topological insulators were predicted in the 1980s, were first observed in 2007 and have been studied intensively since. Made from any number of hundreds of elements, these materials have the capacity to show quantum properties that usually appear only at the microscopic level, but here appear in a material visible to the naked eye.
The experiments reported in Science establish these materials as a distinct state of matter "that exhibits macroscopic quantum mechanical effects," Armitage said. "Usually, we think of quantum mechanics as a theory of small things, but in this system quantum mechanics is appearing on macroscopic length scales. The experiments are made possible by unique instrumentation developed in my laboratory."
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