Efficient Heralding of Photonic Qubits with Apllications to Device   Independent Quantum Key Distribution
  We present an efficient way of heralding photonic qubit signals using linear optics devices. First we show that one can obtain asymptotically perfect heralding and unit success probability with growing resources. Second, we show that even using finite resources, we can improve qualitatively and quantitatively over earlier heralding results. In the latte r scenario, we can obtain perfect heralded photonic qubits while maintaining a finite success probability. We demonstrate the advantage of our heralding scheme by predicting key rates for device independent quantum key distribution, taking imperfections of sources and detectors into account. 
David Pitk\"anen, Xiongfeng Ma, Ricardo Wickert, Peter van Loock,   Norbert L\"utkenhaus
quant-ph