TY - JOUR A1 - Henkel, Carsten A1 - Nest, Mathias A1 - Domokos, P. A1 - Folman, R. T1 - Optical discrimination between spatial decoherence and thermalization of a massive object N2 - We propose an optical ring interferometer to observe environment-induced spatial decoherence of massive objects. The object is held in a harmonic trap and scatters light between degenerate modes of a ring cavity. The output signal of the interferometer permits to monitor the spatial width of the object's wave function. It shows oscillations that arise from coherences between energy eigenstates and that reveal the difference between pure spatial decoherence and that coinciding with energy transfer and heating. Our method is designed to work with a wide variety of masses, ranging from the atomic scale to nanofabricated structures. We give a thorough discussion of its experimental feasibility Y1 - 2004 UR - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/15174 ER -