Physicists may have found a way around Heisenberg's well-known Uncertainty Principle.
The researchers, joining forces from the University of Rochester and the University of Ottawa, came to their conclusions by implementing a new technique to measure polarized light. Normally light waves travel in a number of directions but polarization occurs when the waves travel in a straight line, such as when light is filtered through a crystal. The technique has important implications for the Uncertainty Principle, which states that if some components of a quantum system are known precisely, then others can only be known poorly.
This theory may no longer be valid, thanks to new research methods that were initially developed roughly two years ago. In 2011, scientists at Canada's National Research Council created the technique for measuring wave function, which in quantum mechanics is a way of describing the wave characteristics of a particle. The measurement was unprecedented and, in fact, no one really thought it would be possible since the Uncertainty Principle states that you can't understand a quantum system that way.
But the new team of researchers has confirmed the validity of the technique by deriving a related set of results. They have demonstrated the possibility of directly measuring key related variables, also known as 'conjugate' variables, of a quantum particle or state.
The results have important implications for the future study of quantum physics, including qubits: the basic units of quantum information theory.
"The ability to perform direct measurement of the quantum wavefunction has important future implications for quantum information science," Team Member Robert Boyd said. "Ongoing work in our group involves applying this technique to other systems, for example, measuring the form of a 'mixed' (as opposed to a pure) quantum state."
In developing their technique, the researchers channeled polarized light through two crystals, each with a different thickness. They weakly measured light particles through the thin crystal and more strongly measured other light particles through the thicker crystal. The first measurements were subtle enough so as to keep the quantum state stable, rendering both measurements valid and creating a full portrait of the quantum system through repeated testing.
Results of the study are published in the journal Nature Photonics.
(Edited by Lois Heyman)
