Open-loop and closed-loop control of flying qubits
Marco Lucamarini, Giovanni Di Giuseppe, David Vitali, P. Tombesi · Journal of Physics B Atomic Molecular and Optical Physics · 2011
We describe two recent techniques, along with related experiments, to control and reduce the noise affecting a photon polarization qubit. The first is based on the open-loop 'bang–bang' method, where suitably tailored pulses are implemented on the system to prevent polarization decoherence. This requires only passive elements when the physical system is a photon and the operation is performed in space rather than in time. The second technique is based on closed-loop 'asymmetric feedback', where some quantities are measured and used for a real-time correction of the system dynamics. This technique necessarily requires active electronics to work.