Linear Optical Universal Quantum Gates with Higher Success Probabilities

Universal quantum gates lie at the heart of designing computer. Here two compact circuits for implementing post-selected controlled-phase-flip (CPF) gate and Toffoli with linear optics are constructed assisted by one single photons, respectively. The current existing maximum success probability 1/4 optical CPF is achieved resorting to an ancillary photon rather than entangled pair or photons. Remarkably, presented accomplished 1/30 unity fidelity in principle, without using additional pairs standard decomposition-based approach. Linear implementations universal feasible economical under technology, provide a potential application large-scale computing.