Nonexistence of Entanglement Sudden Death in High NOON States

TL;DR

This paper demonstrates that entanglement sudden death does not occur in high NOON states under pure dephasing, but increasing N accelerates visibility degradation, impacting practical quantum applications.

Contribution

It proves the nonexistence of entanglement sudden death in high NOON states and analyzes how dephasing affects their visibility with increasing N.

Findings

ESD never occurs in these states under pure dephasing

Visibility degrades faster as N increases, scaling inversely with N^2

High N NOON states face practical limitations due to rapid visibility loss

Abstract

We study the dynamics of entanglement in continuous variable quantum systems (CVQS). Specifically, we study the phenomena of Entanglement Sudden Death (ESD) in general two-mode-N-photon states undergoing pure dephasing. We show that for these states, ESD never occurs. These states are generalizations of the so-called High NOON states, shown to decrease the Rayleigh limit of lambda to lambda/N, which promises great improvement in resolution of interference patterns if states with large N are physically realized. However, we show that in dephasing NOON states, the time to reach V_crit, critical visibility, scales inversely with N^2. On the practical level, this shows that as N increases, the visibility degrades much faster, which is likely to be a considerable drawback for any practical application of these states.