Conditions for anti-Zeno effect observation in free-space atomic radiative decay

TL;DR

This paper investigates the conditions under which the anti-Zeno effect can be observed in free-space atomic radiative decay, finding it limited to non-electric-dipolar transitions and proposing an experimental scheme using STIRAP in specific ions.

Contribution

It identifies specific atomic transitions where the anti-Zeno effect can be observed in free space and proposes a feasible experimental protocol using STIRAP.

Findings

Anti-Zeno effect is observable only in non-electric-dipolar transitions.

Electric quadrupole transitions in Ca+ and Sr+ ions are suitable for observing AZE.

Proposed protocol employs STIRAP as a dephasing measurement technique.

Abstract

Frequent measurements can modify the decay of an unstable quantum state with respect to the free dynamics given by Fermi's golden rule. In a landmark article, Nature 405, 546 (2000), Kofman and Kurizki concluded that in quantum decay processes, acceleration of the decay by frequent measurements, called the quantum anti-Zeno effect (AZE), appears to be ubiquitous, while its counterpart, the quantum Zeno effect, is unattainable. However, up to now there have been no experimental observations of the AZE for atomic radiative decay (spontaneous emission) in free space. In this work, making use of analytical results available for hydrogen-like atoms, we find that in free space, only non-electric-dipolar transitions should present an observable AZE, revealing that this effect is consequently much less ubiquitous than first predicted. We then propose an experimental scheme for AZE observation, involving the electric quadrupole transition between D 5/2 and S 1/2 in the heaviest alkali-earth ions Ca + and Sr +. The proposed protocol is based on the STIRAP technique which acts like a dephasing quasi-measurement.