Abstract: A method and system for handling information in a noisy environment in the form of at least one information carrying mode is disclosed. A plurality of encoded modes are generated by linear transformation of the information carrying mode, said encoded modes being provided on respective independent channels. The encoded modes are linearly combined to generate at least one decoded mode. A set of receiver channels is provided for receiving the decoded mode wherein one of said set of receiver channels is designated as a useful channel, and a useful signal is supplied as the decoded mode if it is received on the useful channel an discarded if it is received on the other receiver channels of the set, wherein the useful signal represents said information substantially uncorrupted by noise. The technique is applicable to quantum, classical or mesoscopic environments. The invention also provides a method and system for generating correlated states using a similar filtration technique.