Entanglement breaking channels and entanglement sudden death

TL;DR

This paper investigates how entanglement sudden death depends on initial states and channels, showing that such effects can be understood through effective entanglement breaking channels, with experimental validation using polarization entangled photons.

Contribution

It demonstrates that entanglement sudden death can be predicted by mapping evolution to effective entanglement breaking channels, advancing understanding of entanglement dynamics.

Findings

Entanglement sudden death depends on initial state and channel combination.

Evolution can be mapped to an effective entanglement breaking channel.

Experimental validation with polarization entangled photons confirms theoretical predictions.

Abstract

The occurrence of entanglement sudden death in the evolution of a bipartite system depends on both the initial state and the channel responsible for the evolution. An extreme case is that of entanglement braking channels, which are channels that acting on only one of the subsystems drives them to full disentanglement regardless of the initial state. In general, one can find certain combinations of initial states and channels acting on one or both subsystems that can result in entanglement sudden death or not. Neither the channel nor the initial state, but their combination, is responsible for this effect, but their combination. In this work we show that, in all cases, when entanglement sudden death occurs, the evolution can be mapped to that of an effective entanglement breaking channel on a modified initial state. Our results allow to anticipate which states will suffer entanglement sudden death or not for a given evolution. An experiment with polarization entangled photons demonstrates the utility of this result in a variety of cases.