Reconstructing open quantum system dynamics with limited control

TL;DR

This paper introduces a general method for reconstructing the dynamics of open quantum systems under limited control conditions, enabling better understanding of system behavior even with restricted experimental capabilities.

Contribution

The authors develop a reconstruction scheme applicable to various limited-control scenarios, including only unitary operations or projective measurements, advancing quantum control analysis.

Findings

Reconstruction scheme works with limited operations

Allows detection of initial correlations and memory effects

Applicable to systems with only unitary or projective measurements

Abstract

The dynamics of an open quantum system can be fully described and tomographically reconstructed if the experimenter has complete control over the system of interest. Most real-world experiments do not fulfill this assumption, and the amount of control is restricted by the experimental set-up. That is, the set of performable manipulations of the system is limited. For instance, imagine a set-up where unitary operations are easy to make, but only one measurement at the end of the experiment is allowed. In this paper, we provide a general reconstruction scheme that yields operationally well-defined dynamics for any conceivable kind of experimental situation. If one additional operation can be performed, these `restricted' dynamics allow for the construction of witnesses for initial correlations and the presence of memory effects. We demonstrate the applicability of our framework for the the two important cases where the set of performable operations comprises only unitary operations or projective measurements, respectively, and show that it provides a powerful tool for the description of quantum control experiments.