Non-Markovian to Markovian decay in structured environments with correlated disorder

TL;DR

This paper investigates how correlated disorder in structured environments can induce a transition from non-Markovian to Markovian decay in an atom's spontaneous emission, revealing potential for engineered quantum reservoirs.

Contribution

It demonstrates the control of quantum decay dynamics through correlated disorder, linking localization-delocalization transitions to non-Markovianity in structured environments.

Findings

Disorder induces a transition from non-Markovian to Markovian decay.

The transition is associated with a localization-delocalization phase change.

Dissipative models can effectively replicate the observed non-Markovian behavior.

Abstract

Manipulating the dynamics of open quantum systems is a crucial requirement for large-scale quantum computers. Finding ways to overcome or extend decoherence times is a challenging task. Already at the level of a single two-level atom, its reduced dynamics with respect to a larger environment can be very complex. Structured environments, for instance, can lead to various regimes other than memoryless Markovian spontaneous emission. Here, we consider an atom coupled to an array of coupled cavities in the presence of on-site correlated disorder. The correlation is long-ranged and associated with the trace of a fractional Brownian motion following a power-law spectrum. With the cavity modes playing the role of the environment, we study the dynamics of the spontaneous emission. We observe a change from non-Markovian to Markovian decay in the presence of disorder by tuning the correlation parameter. This is associated with a localization-delocalization transition involving the field modes. Two dissipative models that effectively reproduce the behavior of the non-Markovianity are discussed. The dissipation dynamics of the atom can thus be used to extract information about the phase of the environment. Our results provide a direction in the engineering of disordered quantum systems to function as controllable reservoirs.