Distributed quantum computation with arbitrarily poor photon detection

In a distributed quantum computer, scalability is accomplished by networking together many elementary nodes. Typically the network is optical and internode entanglement involves photon detection. In complex networks the entanglement fidelity may be degraded by the twin problems of photon loss and dark counts. Here we describe an entanglement protocol which can achieve high fidelity even when these issues are arbitrarily severe; indeed the method succeeds with finite probability even if the photon detectors are entirely removed from the network. An experimental demonstration should be possible with existing technologies.