Schemes for creation of N particle entangled Greenberger-Horne-Zeilinger (GHZ) states are important for understanding multi-particle non-classical correlations. Here, a theoretical scheme for creation of a multi-particle GHZ state implemented on a target ensemble of N, $Lambda$ three-level Rydberg atoms and a single Rydberg atom as a control using Stimulated Raman Adiabatic Passage (STIRAP) is presented. We work in the Rydberg blockade regime for the ensemble atoms induced due to excitation of the control atom to a high lying Rydberg level. It is shown that using STIRAP, atoms from one ground state of the ensemble can be adiabatically transferred to the other ground state, depending on the state of the control atom with high fidelity. Measurement of the control atom in a specific basis after this conditional transfer facilitates one-step creation of a N particle GHZ state. A thorough analysis of adiabatic conditions for this scheme and the influence of radiative decay from the excited Rydberg levels is presented. We show that this scheme is immune to the decay rate of the excited level in ensemble atoms and provides a robust way of creating GHZ states.
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