Creating and detecting micro-macro photon-number entanglement by amplifying and de-amplifying a single-photon entangled state

TL;DR

This paper proposes a method to observe micro-macro photon-number entanglement by amplifying and de-amplifying a single-photon entangled state, enabling detection even with photon loss and macro systems of around 100 photons.

Contribution

It introduces a scheme combining amplification, de-amplification, and homodyne tomography to observe photon-number entanglement at the micro-macro scale.

Findings

Micro-macro entanglement can be detected with about 100 photons in the macro system.

The scheme is robust against reasonable photon loss.

Superposition of states with mean photon numbers differing by a factor of three.

Abstract

We propose a scheme for the observation of micro-macro entanglement in photon number based on amplifying and de-amplifying a single-photon entangled state in combination with homodyne quantum state tomography. The created micro-macro entangled state, which exists between the amplification and de-amplification steps, is a superposition of two components with mean photon numbers that differ by approximately a factor of three. We show that for reasonable values of photon loss it should be possible to detect micro-macro photon-number entanglement where the macro system has a mean number of one hundred photons or more.