Robust creation of arbitrary-sized Dicke states of trapped ions by global addressing
I. E. Linington and N. V. Vitanov

We propose a novel technique for the creation of maximally entangled symmetric Dicke states in an ion trap using adiabatic passage, which requires only a pair of chirped pulses from a single laser and is applicable to any number of ions and excitations. By utilising a particular factorisation of the Hilbert space for multi-level ladders we show that the problem can be reduced to `bow-tie' configuration energy-level crossings. This technique is naturally robust against fluctuations in the laser intensity and the chirp rate. Even when realistic heating rates are considered, we estimate that the overall fidelity should remain high (e.g. $98\%$ for a $10$-ion Dicke state), which represents a significant improvement over traditional approaches. This method may also be used to create number states of a collective vibrational mode of the ions.

© 2008 The American Physical Society.