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arXiv · 0808.1926

Maximal Success Probabilities of Linear-Optical Quantum Gates

Dmitry B. Uskov·Lev Kaplan·A. Matthew Smith·Sean D. Huver·Jonathan P. Dowling
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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 $S=2/27$ 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 $S=0.00340$. This compares well with $S=(2/27)^2/2 \approx 0.00274$, 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)].

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Dmitry B. Uskov, Lev Kaplan, A. Matthew Smith, Sean D. Huver, Jonathan P. Dowling. 2008-08-14. Maximal Success Probabilities of Linear-Optical Quantum Gates. https://doi.org/10.1103/physreva.79.042326

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