Information-flux approach to multiple-spin dynamics

TL;DR

The paper introduces the concept of information flux in many-body quantum systems, providing a flexible tool to optimize initial states and couplings for tasks like quantum cloning and state transfer.

Contribution

It formalizes the information flux concept and demonstrates its application in designing and analyzing many-body quantum dynamics, including non-unitary processes.

Findings

Effective in designing initial states for quantum protocols

Applicable to both unitary and non-unitary dynamics

Facilitates numerical analysis of complex quantum systems

Abstract

We introduce and formalize the concept of information flux in a many-body register as the influence that the dynamics of a specific element receive from any other element of the register. By quantifying the information flux in a protocol, we can design the most appropriate initial state of the system and, noticeably, the distribution of coupling strengths among the parts of the register itself. The intuitive nature of this tool and its flexibility, which allow for easily manageable numerical approaches when analytic expressions are not straightforward, are greatly useful in interacting many-body systems such as quantum spin chains. We illustrate the use of this concept in quantum cloning and quantum state transfer and we also sketch its extension to non-unitary dynamics.