Getting around the 'uncertainty principle': Physicists make first direct measurements of polarization states of light

Rochester and the University of Ottawa have applied a recently developed technique to directly measure for the first time the polarization states of light. Their work both overcomes some important challenges of Heisenberg's famous Uncertainty Principle and also is applicable to qubits, the building blocks of quantum information theory.

They report their results in a paper published this week in Nature Photonics.

The direct measurement technique was first developed in 2011 by scientists at the National Research Council, Canada, to measure the wavefunction – a way of determining the state of a quantum system.

Such direct measurements of the wavefunction had long seemed impossible because of a key tenet of the uncertainty principle – the idea that certain properties of a quantum system could be known only poorly if certain other related properties were known with precision. The ability to make these measurements directly challenges the idea that full understanding of a quantum system could never come from direct observation.