Photon echoes for a system of large negative spin and few photons

TL;DR

This paper investigates persistent photon echoes in a system of many two-level molecules with a large negative spin interacting with few photons, revealing unique revival behaviors and disentanglement dynamics not seen in typical small-atom, high-photon systems.

Contribution

It provides the first detailed analysis of photon echoes in a large negative spin system with few photons, highlighting distinct revival times and disentanglement phenomena.

Findings

Persistent echoes re-emerge long after initial decay.

Disentanglement occurs only at revival times.

Echo characteristics differ from systems with few TLMs and many photons.

Abstract

Persistent photon echoes are seen for the case of a large number of two-level molecules (TLMs) prepared initially in the all-down state (large negative spin) interacting with a photon distribution with a small mean photon number in a lossless cavity. This case is interesting since 1) it has not been significantly addressed in the past; 2) the characteristic times associated with revival are not what is seen for the more frequently addressed problem of a few TLMs interacting with a photon distribution with a large mean photon number; 3) long after the echoes die out, they re-emerge completely at a much later time; and 4) the existence of echoes is not predicated on the initial photon distribution being the coherent state or Glauber distribution. Entropy, entanglement, and the Q function are considered. It is found that disentanglement only occurs at the revival times as evidenced by the entropy going to 0 and the Q function returning to the value seen at time=0. Comparison to the more normally seen results for large mean photon number and small numbers of TLMs are discussed. Finally this paper acts as a general reference for future refereed publications.