Sudden death, birth and stable entanglement in a two-qubit Heisenberg XY spin chain

TL;DR

This paper studies how entanglement in a two-qubit Heisenberg XY spin chain evolves under decoherence, revealing phenomena like sudden death and birth, and how it can be controlled or stabilized through system parameters.

Contribution

It demonstrates the conditions for entanglement sudden death, birth, and stability in a two-qubit Heisenberg XY model with decoherence, highlighting control via system parameters.

Findings

Entanglement exhibits sudden death and birth during evolution.

External magnetic field and environment influence entanglement dynamics.

Stable entanglement can exist despite decoherence.

Abstract

Taking the decoherence effect due to population relaxation into account, we investigate the entanglement properties for two qubits in the Heisenberg XY interaction and subject to an external magnetic field. It is found that the phenomenon of entanglement sudden death (ESD) as well as sudden birth(ESB) appear during the evolution process for particular initial states. The influence of the external magnetic field and the spin environment on ESD and ESB are addressed in detail. It is shown that the concurrence, a measure of entanglement, can be controlled by tuning the parameters of the spin chain, such as the anisotropic parameter, external magnetic field, and the coupling strength with their environment. In particular, we find that a critical anisotropy constant exists, above which ESB vanishes while ESD appears. It is also notable that stable entanglement, which is independent of different initial states of the qubits, occurs even in the presence of decoherence.