Free lunches with chips and coherent beams: from Ramsey fringes to integrated circuit inspection

Interference between coherent photon pulses separated in time yields the famous Ramsey fringes, which allow the dynamics of objects exposed to the pulses to be characterized with much greater precision than suggested by the Heisenberg uncertainty relation applied to the pulse bandwidth. The same applies for coherent photon beams separated in space, which leads to the construction of images of objects much larger than the wavelength of light, with  resolution limited only by photon statistics for high angle scattering. We show that both of these measurement techniques follow very naturally from consideration of simple slit-based optical interferometers, and that they can be implemented with electron accelerator driven sources - i.e. free electron lasers and synchrotrons - producing temporally and/or spatially coherent photon beams. The objects in the beams are common silicon devices, and the experiments yield demonstrations of both fundamental concepts in quantum physics as well as - on the side of applied science - the ability to “read” integrated circuits in three dimensions.

Speaker: Gabriel Aeppli, ETH Zürich, EPF Lausanne and Paul Scherrer Institut, Switzerland