Entanglement and phase properties of noisy N00N states

TL;DR

This paper investigates the quantum properties of noisy N00N states in atmospheric channels, demonstrating their potential for quantum metrology despite noise and loss, and providing bounds for entanglement verification.

Contribution

It provides a theoretical analysis of noisy N00N states in atmospheric channels, showing they can still surpass classical phase resolution and identifying entanglement after propagation.

Findings

Noisy N00N states can achieve phase resolution beyond classical limits.

Entanglement persists in noisy N00N states after atmospheric propagation.

Explicit bounds for experimental verification of entanglement are formulated.

Abstract

Quantum metrology and quantum information necessitate a profound study of suitable states. Attenuations induced by free-space communication links or fluctuations in the generation of such states limit the quantum enhancement in possible applications. For this reason we investigate quantum features of mixtures of so-called N00N states propagating in atmospheric channels. First, we show that noisy N00N states can still yield a phase resolution beyond classical limitations. Second, we identify entanglement of noisy N00N states after propagation in fluctuating loss channels. To do so, we apply the partial transposition criterion. Our theoretical analysis formulates explicit bounds which are indispensable for experimental verification of quantum entanglement and applications in quantum metrology.