The Zeno and anti-Zeno effects: studying modified decay rates for spin-boson models with both strong and weak system-environment couplings

TL;DR

This study investigates how repeated measurements affect quantum decay rates in spin-boson models with both strong and weak system-environment couplings, revealing that system evolution does not significantly alter the Zeno and anti-Zeno effects.

Contribution

It extends the analysis of quantum decay modifications to large spin-boson systems with mixed coupling strengths, using polaron transformation and perturbation theory.

Findings

Strong and weak couplings produce similar effects as with system evolution.

Single and multiple two-level systems show qualitative and quantitative differences.

System evolution has negligible impact on the Zeno and anti-Zeno effects.

Abstract

In this paper, we look into what happens to a quantum system under repeated measurements if system evolution is removed before each measurement is performed. Beginning with investigating a single two-level system coupled to two independent baths of harmonic oscillators, we move to replacing it with a large collection of such systems, thereby invoking the large spin-boson model. Whereas each of our two-level systems interacts strongly with one of the aforementioned baths, it interacts weakly with the other. A polaron transformation is used to make it possible for the problem in the strong coupling regime to be treated with perturbation theory. We find that the case involving a single two-level system exhibits qualitative and quantitative differences from the case involving a collection of them; however, the general effects of strong and weak couplings turn out to be the same as those in the presence of system evolution, something which allows us to establish that system evolution has no practical bearing on any of these effects.