The development of quantum mechanics, the underlying laws that govern matter and energy on the scale of atoms and electrons, has not only revolutionized our understanding of the universe but also has given us such technologies as the transistor, the laser and magnetic resonance imaging. Now Philip H. Bucksbaum and his co-workers at the University of Michigan have combined several recently developed techniques with a feedback system to control the very essence of quantum particles: their wave functions. The Bucksbaum experiment "is true quantum engineering," says physicist Michael G. Raymer of the University of Oregon. "It should open up many new possibilities, most of which we cannot even imagine now."
A wave function defines the physical state of a quantum object. Wave functions are slippery characters, tied to probabilities, not certainties. They obey the famous Heisenberg uncertainty principle: if one characteristic is well defined, a related feature must be highly uncertain. For instance, an electron with a very precise position must have a wide range of possible velocities. Nevertheless, during the past decade a number of research groups have assembled techniques for manipulating and analyzing complete wave functions in detail.