One-Step Implementation of Collective Anti-Blockade in a Rydberg Ring

In contrast to Rydberg blockade, Rydberg anti-blockade allows multiple atoms to be simultaneously excited in the presence of significant nonlocal interactions and can lead to distinct phenomena and applications. This inspires us to examine here general conditions, numerical verifications, and realistic restrictions regarding the collective anti-blockade excitations of N Rydberg atoms equally arranged along a ring. We find that by adjusting the detuning of a pump field to compensate for nonlocal interactions between one atom and all others, it is viable to realize resonant excitations of N atoms but suppress far-detuned excitations of N−1 and fewer atoms under different conditions for an odd and an even number of atoms. Population dynamics of this Rydberg ring further show that one-step anti-blockade implementation can be attained at a cutoff time of the pump field, which increases quickly with the number of atoms. Hence, roughly perfect anti-blockade excitations are attainable only for a not-too-large N due to inevitable spontaneous Rydberg decay.