Error Corrected Interferometry

Abstract

Physics Optical interferometers can probe an object at high resolution through its effect on their interference pattern. Neutrons also have an associated wavelength—the de Broglie wavelength— which is very much smaller than any optical wavelength and can in principle provide information on an atomic size scale. However, neutron interferometers are susceptible to low-frequency mechanical vibrations of the interferometer itself. Pushin et al. show that ideas based on error correction protocols used in quantum information science can be carried over to suppress such effects of environmental noise. They show that the formation of decoherence-free subspaces (DFSs), special states in which the system is manipulated in such a way as to protect it from the surrounding environment, can be formed by carefully designing the setup of the system. In this case, they use a figure-eight interferometer carved into a single ingot of silicon instead of the usual two-arm interferometer setup and show that a DFS formed at the center of the interferometer suppresses the effect of environmental noise. Phys. Rev. Lett. 107 , 150401 (2011).