Influence of dissipation on the extraction of quantum states via repeated measurements

TL;DR

This paper investigates how environmental dissipation affects the ability to purify quantum states through repeated measurements, analyzing a two-spin system in a bosonic bath to assess purification effectiveness under realistic conditions.

Contribution

It introduces a general framework for understanding dissipation effects on quantum state purification via repeated measurements, extending prior idealized models to include environmental interactions.

Findings

Purification remains feasible under certain dissipation conditions.

Higher bath temperatures reduce purification effectiveness.

Optimal parameters can mitigate environmental effects.

Abstract

A quantum system put in interaction with another one that is repeatedly measured is subject to a non-unitary dynamics, through which it is possible to extract subspaces. This key idea has been exploited to propose schemes aimed at the generation of pure quantum states (purification). All such schemes have so far been considered in the ideal situations of isolated systems. In this paper, we analyze the influence of non-negligible interactions with environment during the extraction process, with the scope of investigating the possibility of purifying the state of a system in spite of the sources of dissipation. A general framework is presented and a paradigmatic example consisting of two interacting spins immersed in a bosonic bath is studied. The effectiveness of the purification scheme is discussed in terms of purity for different values of the relevant parameters and in connection with the bath temperature.