Deterministic Conversion from GHZ State to W State with Rydberg Superatoms

Abstract Quantum entanglement is playing an increasingly crucial role in the field of quantum information. The conversion between different types of entangled states, especially for GHZ state and W state, can greatly enhance the efficiency of quantum information processing. Here, a two‐step scheme is proposed to realize the conversion between GHZ state and W state with Rydberg superatoms, in which the collective states of superatom are used to encode quantum information. In the first step, let a single‐photon pulse pass through two cavities that trap superatoms in sequence and detect the state of photon to complete this task. In the second step, shortcuts are employed to adiabaticity based on superadiabatic technique and design appropriate Rabi frequencies for the system. The numerical simulations demonstrate that this scheme possesses a high fidelity and exhibits robustness against detrimental effects such as atomic spontaneous emission, cavity losses, fiber photon leakages and noise. Furthermore, the intricate pulses within this scheme are decomposed into a linear superposition of Gaussian pulses, enhancing experimental feasibility. Finally, the scheme is extended to deal with the scenario of multi‐superatom. This method provides a way to convert other types of entangled states.