Phys. Rev. Lett. 112, 253602 (2014)


The Heisenberg uncertainty principle states that the simultaneous knowledge of complementary observables, such as position and momentum, of a quantum system will always reach a fundamental information limit; this means that the more precisely you measure one observable, the less knowledge you'll end up having about its complementary. Now, Gregory Howland and colleagues show how this fundamental limit of quantum mechanics can be bypassed in the measurement of the photons' position and momentum. Their method records information about the photons' momentum distribution directly from CCD (charge-coupled device) images. Before CCD measurements, the momentum information is slightly disturbed as a result of encountering a series of filtering masks. The role of this pre-CCD-filtering is to allow the filtered photon state to carry a small amount of information about the photons' position distribution. This information is then efficiently extracted by compressed sensing. Using this methodology the authors are able to recover both position and momentum information of four different objects. This result does not invalidate the Heisenberg uncertainty principle per se, but it does show how, by measuring a mixed signal of complementary observables, it is possible to use information efficiently.