Their technique could also be used to test superpositions on even more macroscopic scales, such as with larger atoms or molecules. As such, their experiment constrains theories of physics that aim to replace quantum mechanics. is based on a stringent test considered to be the gold standard for confirming that a superposition exists. Larger objects have been observed to have such inherently quantum properties, but the observation of Robens et al. Using this setup, Carsten Robens at the University of Bonn, Germany, and his colleagues demonstrated that a cesium atom travels in a truly nonclassical fashion, moving as a quantum superposition of states and thus occupying more than one distinct location at a time. Does this mean quantum physics fundamentally doesn’t apply to objects beyond a certain size? A new experiment that allows the motion of a large atom in an optical lattice to be tracked could help in the search for a size cutoff.

×Įveryday experience tells us that big objects-eggs and humans-do not appear to exist in a superposition of states like that possible for more quantum objects, such as electrons. The authors prepared the atom in a superposition of two atomic states, which was equivalent to the atom simultaneously sitting in the red optical carton and the blue optical carton, and determined the atom’s position by detecting its fluorescence as the two cartons were slid apart. The fields have a periodic “egg-carton”-like potential. APS/ Alan Stonebraker Figure 1: In the experimental test by Robens et al., a large atom (cesium) moves in one of two possible optical fields-here indicated in red and blue.

Principle of superposition in physics