Robust preparation of Dicke-states by multi-ion STIRAP

David B. Hume, C. W. Chou, Till Rosenband +1 more

Mang Feng

Chitra Rangan

I. E. Linington, Nikolay V. Vitanov

We propose a simple technique for the generation of arbitrary-sized Dicke states in a chain of trapped ions. The method uses global addressing of the entire chain by two pairs of delayed but partially overlapping laser pulses to engineer a collective adiabatic passage along a multi-ion dark state. Our technique, which is a many-particle generalization of the stimulated Raman adiabatic passage technique, is decoherence free with respect to spontaneous emission and robust against moderate fluctuations in the experimental parameters. Furthermore, because the process is very rapid, the effects of heating are almost negligible under realistic experimental conditions. We predict that the overall fidelity of synthesis of a Dicke state involving ten ions sharing two excitations should approach 98% with currently achievable experimental parameters.

Atsushi Noguchi, Kenji Toyoda, Shinji Urabe

We generate half-excited symmetric Dicke states of two and four ions. We use multilevel stimulated Raman adiabatic passage whose intermediate states are phonon Fock states. This process corresponds to the spin squeezing operation and half-excited Dicke states are generated during multilevel stimulated Raman adiabatic passage. This method does not require local access for each ion or the preparation of phonon Fock states. Furthermore, it is robust since it is an adiabatic process. We evaluate the Dicke state using a witness operator and determine the upper and lower bounds of the fidelity without using full quantum tomography.

Andreas Bärtschi, Stephan Eidenbenz