The quantum Zeno and anti-Zeno effects in the strong coupling regime

TL;DR

This paper investigates the quantum Zeno and anti-Zeno effects in a strongly coupled two-level system, revealing a transition in decay behaviors when preparing different quantum states, with implications for quantum control.

Contribution

It introduces a polaron transformation and perturbative approach to analyze the Zeno effects in strong coupling regimes for arbitrary states.

Findings

Decay rate transition as state varies from excited to superposition

Strong coupling effects significantly alter Zeno and anti-Zeno behaviors

Results aid in quantum control of two-level systems in complex environments

Abstract

It is well known that repeated projective measurements can either speed up (the Zeno effect) or slow down (the anti-Zeno effect) quantum evolution. Until now, however, studies of these effects for a two-level system interacting strongly with its environment have focused on repeatedly preparing the excited state of the two-level system via the projective measurements. In this paper, we consider the repeated preparation of an arbitrary state of a two-level system that is interacting strongly with an environment of harmonic oscillators. To handle the strong interaction, we perform a polaron transformation, and thereafter use a perturbative approach to calculate the decay rates for the system. Upon calculating the decay rates, we discover that there is a transition in their qualitative behaviors as the state being repeatedly prepared moves away from the excited state towards a superposition of the ground and excited states. Our results should be useful for the quantum control of a two-level system interacting with its environment.