Arbitrary state controlled-unitary gate by adiabatic passage (6 pages)

Ju-Mei Chen, Lin-Mei Liang, Cheng-Zu Li +1 more

Jiří Vala, Jiang Zhang, Shankar Sastry +1 more

X. Lacour, Nicolas Sangouard, S. Guérin +1 more

We propose a fast scheme involving atoms fixed in an optical cavity to directly implement the universal controlled-unitary gate. The present technique based on adiabatic passage uses dark states well suited for the controlled-rotation operation. We show that these dark states allow the robust implementation of a gate that is a generalization of the controlled-unitary gate to the case where the control qubit can be selected to be an arbitrary state. This gate has potential applications to the rapid implementation of quantum algorithms such as the projective measurement algorithm. This process is decoherence-free since excited atomic states and cavity modes are not populated during the dynamics.

M. Andrecut, Mazhar Ali

Hayato Goto, Kouichi Ichimura

A new implementation of quantum gates by adiabatic passage with an optical cavity is proposed. This implementation allows one to perform not only elementary gates, such as one-qubit gates and a controlled-NOT gate, but also multiqubit controlled unitary gates. Some quantum gates are numerically simulated. From the simulation results, it is concluded that this implementation of the three-qubit controlled gates is more efficient than decomposing into the elementary gates.

D. V. Averin