Deutsch, Toffoli, and CNOT Gates via Rydberg Blockade of Neutral Atoms

Universal quantum gates and quantum error correction (QEC) lie at the heart of quantum-information science. Large-scale quantum computing depends on a universal set of quantum gates, in which some gates may be easily carried out, while others are restricted to certain physical systems. There is a unique threequbit quantum gate called the Deutsch gate [D(theta)], from which a circuit can be constructed so that any feasible quantum computing is attainable. We design an easily realizable D(theta) by using the Rydberg blockade of neutral atoms, where theta can be tuned to any value in [0, pi] by adjusting the strengths of external control fields. Using similar protocols, we further show that both the Toffoli and controlled-Nor gates can be achieved with only three laser pulses. The Toffoli gate, being universal for classical reversible computing, is also useful for QEC, which plays an important role in quantum communication and faulttolerant quantum computation. The possibility and speed of realizing these gates shed light on the study of quantum information with neutral atoms.