Detection devices in entanglement-based optical state preparation - art. no. 033812

We study the use of detection devices in entanglement-based state preparati on. In particular we consider optical detection devices such as single-phot on sensitivity detectors, single-photon resolution detectors; and detector cascades (with an emphasis on the performance of realistic detectors). We d evelop an extensive theory for the use of these devices. In entanglement-ba sed state preparation we perform measurements on subsystems, and we therefo re need precise bounds on the distinguishability of these measurements (thi s is fundamentally different from, e.g., tomography, where an ensemble of i dentical states is used to determine probability distributions, etc.). To t his end, we introduce the confidence of preparation, which may also be used to quantify the performance of detection devices in entanglement-based pre paration. We give a general expression for detector cascades of arbitrary s ize for the detection up to two photons. We show that, contrary to the gene ral belief, cascading does not give a practical advantage over detectors wi th single-photon resolution in entanglement-based state preparation.