A unified picture for quantum Zeno and anti-Zeno effects

The quantum Zeno effect is a striking feature of quantum mechanics with foundational implications and practical applications in quantum control, error suppression, and error correction. The effect has branched off into a variety of different interpretations, making it easy to miss the unifying features of the underlying effect. In particular, the quantum Zeno effect has been studied in the context of both selective and nonselective measurements; for both pulsed and continuous interactions; for suppression and enhancement of decay (Zeno / anti-Zeno effects); and even in the absence of measurement entirely. This concise review presents a unified picture of these effects by examining how they all arise in the context of a driven qubit subjected to measurements or dissipation. Zeno and anti-Zeno effects are revealed as regimes of a unified effect that appears whenever a measurement-like process competes with a non-commuting evolution. The current landscape of Zeno and anti-Zeno effects is reviewed through this unifying lens, with a focus on experimental applications and implementations. The quantum Zeno effect is found to be both ubiquitous and essential for the future of near-term quantum computing.