Entanglement between uncoupled modes with time-dependent complex frequencies

TL;DR

This paper provides a unified framework for analyzing the entanglement dynamics of uncoupled bosonic modes under time-dependent non-Hermitian Hamiltonians with complex frequencies, revealing non-zero entanglement without direct interaction.

Contribution

It introduces a general method for describing the evolution of non-Hermitian systems using algebraic and Dyson map techniques, highlighting entanglement emergence from non-local metric effects.

Findings

Uncoupled modes can become entangled due to non-Hermitian dynamics.

Time-dependent complex frequencies influence the entanglement properties.

The non-local metric encodes entanglement generation without mode coupling.

Abstract

In this work we present the general unified description for the unitary time-evolution generated by time-dependent non-Hermitian Hamiltonians embedding the bosonic representations of $\mathfrak{su}(1,1)$ and $\mathfrak{su}(2)$ Lie algebras. We take into account a time-dependent Hermitian Dyson maps written in terms of the elements of those algebras with the relation between non-Hermitian and its Hermitian counterpart being independent of the algebra realization. As a direct consequence, we verify that a time-evolved state of uncoupled modes modulated by a time-dependent complex frequency may exhibits a non-zero entanglement even when the cross-operators, typical of the interaction between modes, are absent. This is due the non-local nature of the non-trivial dynamical Hilbert space metric encoded in the time-dependent parameters of the general Hermitian Dyson map, which depend on the imaginary part of the complex frequency.