Amplification of polarization NOON states

TL;DR

This paper investigates the amplification of polarization NOON states using quantum optical amplifiers, demonstrating enhanced signal and resilience for N-photon states, with a focus on non-collinear schemes to preserve phase features.

Contribution

It introduces a non-collinear QIOPA scheme for amplifying N-photon NOON states, overcoming limitations of collinear amplification and maintaining phase resolution features.

Findings

Stimulated emission enhances signal visibility compared to spontaneous emission.

Collinear amplification cannot effectively amplify N>2 photon states due to oscillation patterns.

Non-collinear QIOPA preserves mp;N features and shows high resilience to losses.

Abstract

NOON states are path entangled states which can be exploited to enhance phase resolution in interferometric measurements. In the present paper we analyze the quantum states obtained by optical parametric amplification of polarization NOON states. First we study, theoretically and experimentally, the amplification of a 2-photon state by a collinear Quantum Injected Optical Parametric Amplifier (QIOPA). We compared the stimulated emission regime with the spontaneous one, studied by Sciarrino et al. (PRA 77, 012324), finding comparable visibilities between the two cases but an enhancement of the signal in the stimulated case. As a second step, we show that the collinear amplifier cannot be successfully used for amplifying N-photon states with N>2 due to the intrinsic \lambda/4 oscillation pattern of the crystal. To overcome this limitation, we propose to adopt a scheme for the amplification of a generic state based on a non-collinear QIOPA and we show that the state obtained by the amplification process preserves \lambda/N feature and exhibits a high resilience to losses. Furthermore, an asymptotic unity visibility can be obtained when correlation functions with sufficiently high order M are analyzed.