Abstract: A signal manipulator, comprising: an input for multiplexed signal, a demultiplexer for separating the multiplexed signal into separate components, a retransmitter unit being configured to receive a first component from the separated components and retransmit said received first component at a higher power than it is received; a bypass channel being configured to receive a second component from the components separated by the demultiplexer; and a multiplexer for multiplexing the first and second components, wherein the retransmitter is configured to regulate the power of the first component such that the power of the multiplexed signal leaving the multiplexer is ?5 dBm or less.

Abstract: A photon detection system is provided comprising a photon detector, configured to detect photons during intervals when in a receiving state and to output a signal when a photon is received, a controller, configured to generate a time varying gating signal wherein said gating signal switches said detector between the receiving state and a non-receiving state, said controller being configured to receive and process information relating to the times photons are expected to arrive at said detector, the controller being configured to generate the gating signal such that the photon detector is in the receiving state for intervals when photons are expected and also in the receiving state for additional intervals between the intervals when the photons are expected; a detection module, configured to distinguish between when the output signal from the photon detector corresponds to an interval when photons are expected and said additional intervals.