paper

Maximal Success Probabilities of Linear-Optical Quantum Gates

arXiv:0808.1926 · doi:10.1103/PhysRevA.79.042326

Abstract

Numerical optimization is used to design linear-optical devices that implement a desired quantum gate with perfect fidelity, while maximizing the success rate. For the 2-qubit CS (or CNOT) gate, we provide numerical evidence that the maximum success rate is using two unentangled ancilla resources; interestingly, additional ancilla resources do not increase the success rate. For the 3-qubit Toffoli gate, we show that perfect fidelity is obtained with only three unentangled ancilla photons -- less than in any existing scheme -- with a maximum . This compares well with , obtainable by combining two CNOT gates and a passive quantum filter [PRA 68, 064303 (2003)]. The general optimization approach can easily be applied to other areas of interest, such as quantum error correction, cryptography, and metrology [arXiv:0807.4906, PRL 99 070801 (2007)].

4 pages, 3 figures, presented at Quantum Computing and Algorithms Program Review in Atlanta, GA (August 11-15, 2008)

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